Study on Spinnability of Arabinoxylan Extracted From Barley Husks

Study on Spinnability of Arabinoxylan Extracted From Barley Husks | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Study on Spinnability of Arabinoxylan Extracted From Barley Husks Svetlana Butylina, Krista Koljonen, Salla Hiltunen, Katri Laatikainen This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-1210254/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 6 You are reading this latest preprint version Abstract Valorisation of bio-based materials derived from agricultural and industrial side-streams or waste-streams is a basis of circular economy. However, the success of it depends on the full understanding of materials and finding their optimal way of processing. Barley husk is a side-stream waste material derived from the starch and ethanol production. This study is focused on the processability of the arabinoxylan extracted from barley husk using the electrospinning technique to produce thin xylan-poly(vinyl alcohol) fibers. As a comparison, lignin-free xylan of beech wood was used. The properties of spinning solutions and resulting nanofibrous mats were assessed by using rheological measurements, FTIR spectroscopy, scanning electron microscopy and contact angle measurements. It was found that solubility plays a crucial role in the spinnability of xylan extracts. Decrease in viscosity of arabinoxylan achieved by decreasing its concentration was found to improve the jet stability but at the same time, to reduce the diameter of spun fibre. Hydrophilicity of nanofibrous mats were strongly affected by the type of xylan and solvent used. Cellular Metabolism Cellular & Molecular Neuroscience Arabinoxylan electrospinning nanofibers rheology FTIR spectroscopy contact angle Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Introduction Circular economy has increased the usage of the biopolymers derived from various side streams and industrial waste materials both in agriculture and wood processing. The importance of circular economy in the fight against microplastic and carbon dioxide emissions has been well acknowledged in recent years (Forni 2020 ). Biopolymers originated from industrial and agricultural side streams can be divided into three groups such as polysaccharides (cellulose, hemicellulose, starch, chitin), proteins (silk, collagen) and phenol-based polymer lignin (Moohan et al. 2019 ). Hemicelluloses are of specific interest because they represent second most abundant group of biopolymers after cellulose and represent 30-40% of agricultural residues (Sun et al. 2011 ), but compared to cellulose is being barely utilized as raw material (Peng et al. 2014). Among all types of hemicelluloses, xylans are the most abundant type, which can be further divided into subclasses: homoxylans, glucuronoxylans, (arabino)glucuronoxylans, arabinoxylans, (glucurono)arabinoxylans and heteroxylans (Ebringerová 2006 ). The fractionation and purification of some specific xylans from plant-based materials is complicated, costly, and time-consuming process (Ferrari et al. 2015 ). Use of crude (non-refined) xylan-containing extracts wherever it is possible can significantly reduce the cost of product. Increased interest in barley husks can be explained by significance of barley ( Hordeum vulgare ) as crop plant. Finland produces barley in amount of 1,4 million tons per year (Luke 2020), whereas worldwide annual production is 160 million tons (FAO 2019). Husk is the outermost layer of the grain which forms 10–20% of the grain weight (Holopainen- Mantila 2015; Bhardwaj et al. 2020 ) and a side-stream waste material from the manufacture of starch and ethanol (Köhnke et al. 2009 ). Traditionally, barley husk is peeled off and burned. Extraction method used can affect chemical composition of barley husk material (Höije et al. 2005 , 2006 ; Börjesson 2018), however, mostly it consists of hemicelluloses, i.e. arabinoxylan, and cellulose with smaller amounts of lignin, protein, starch and fat. Recently, possibilities to exploit the fractions of barley husk in high-value product for different applications have been studied. Lähde et al. ( 2020 ) has described synthesis of nanostructured silicon carbide and graphene-like carbon from the silica extracted from barley husk. The transformation of cellulose fraction of barley husk into nanocellulose by sulphuric acid hydrolysis was studied by Börjesson et al. ( 2018 ). Höije et al. ( 2005 ) have published research on development of oxygen barrier coatings from arabinoxylans extracted of barley husks. Berglund et al. ( 2018 ) have studied the formation of composite aerogels from lignin-containing arabinoxylan and cellulose nanofibers which could be applied in the soft tissue engineering. Electrospinning is a distinguished method for the preparation of nanofibers consisting of dissolved or melt polymers and biopolymers or their blends (Frenot and Chronakis 2003 ; Subbiah et al. 2005 ; Agarwal et al. 2009 , 2016 ). In electrospinning process, a polymer solution or melt is placed into a syringe with a millimeter-size nozzle and is subjected to high electric field. Under the applied electrostatic force, the polymer is ejected from the nozzle and transported and deposited on a collector, which also serves as the ground for the electrical charges. Electrospun fibers have been widely used in several applications including scaffolds for tissue engineering, drug delivery, medical implants, biosensors, wound dressing (Rogina 2014 ), water filtration and packaging materials (Torres-Giner et al. 2018 ). Usually, the electrospun fibers have unique properties, such as high surface area-to-volume ratio, high pore interconnectivity and easy surface functionalization. Several studies have been published on spinnability of various xylans. Krishnan et al. ( 2012 ) and Venugopal et al. ( 2013 ) have studied the beech-wood derived glucuronoxylan and Duan et al. ( 2019 ) have electrospun the arabinoglucuronoxylan extracted from straw fibres. In these studies, different solvents were used: 1N sodium hydroxide and hot water, respectively. Most often, poly(vinyl alcohol) (PVA) and poly(ethylene oxide) (PEO) have been used to ensure the adequate entanglements and to facilitate the electrospinning of the xylan solutions. Due to the excellent properties of PVA, such as water-solubility, non-toxicity, biodegradability, it has been widely used in different nanofiber composite materials, for example, together with nanoclay (Ristolainen et al. 2006 ), chitosan (Park et al. 2009 ), aloe vera (Abdullah et al. 2014) and graphene oxide (Wang et al. 2012 ). Limited dispersion and solubilization of biopolymers are factors which make their electrospinning process challenging (Peresin and Rojas 2014 ). It has been shown in numerous studies (Ebringerová and Heinze 2000; Ebringerová 2006 ; Glasser et al. 2000 ; Roos et al. 2009 ) that solubility of xylans and their rheological behaviour depend on their plant origin, molecular structure, and method of extraction. Therefore, solubility is one of the subjects which will be addressed in the present study. In this work the spinnability of arabinoxylan extract from barley husks was studied concentrating especially on the effects of alkaline, concentration of arabinoxylan extract and surfactant addition. The properties of the electrospinning solution were determined and connected with the properties of the electrospun materials. The xylan from beechwood was used as a reference. The quality of fibres was assessed by scanning electron microscopy and their chemistry was studied by FTIR spectroscopy and contact angle measurements. Materials And Methods Material The commercial grade poly (vinyl alcohol), PVA (Aldrich Chemistry), had a molecular weight of 89-98 kg/mol and 99% degree of hydrolysis. Arabinoxylan (AXyl) (Xylophane AB, Gothenburg, Sweden) was an extract from barley husk. According to the manufacturer specification, the sugar composition of this extract consisted of xylose (48.5%), arabinose (11.7%) and glucose (3.8%). The non-hemicellulose components of extract consisted of Klason lignin (19.6%), fat (4.2%), ash (4.3%) protein (6.8%) and starch (less than 1%). European beechwood xylan was pharmaceutical grade (Iris Biotech GmbH) consisting of poly(beta-D-xylopyranose [1→4]) linkages. Both, the barley husk xylan and the beechwood xylan were used without further treatment. Benzalkonium chloride, BAC, (Fluka ≥ 95.0%) was used as a cationic surfactant. It contained H 2 O ≤ 10% and ash as SO 4 ≤ 0.1% and was a mixture of 60% C 12 and 40% C 14 homologues. The average molar mass of BAC was 350 g/mol and critical micelle concentration (CMC) was 3 mM determined in 0.1 mM NaCl (Turku and Sainio 2009). Methods Preparation of spinning solutions Two types of approach were used to dissolve xylan, referred in this study as Method A and B. In the Method A described by Duan et al. (2019), the xylan powder is dissolved in water under vigorous magnetic stirring at 80 °C for 24 hours in tightly sealed flask as illustrated in Figure 1. Thereafter, the PVA powder was added into prepared solution and heated at 80 °C under stirring at 500 rpm for 3 hours to complete the dissolution of PVA followed by the overnight stirring without heating. The 10 mmol of cationic surfactant, benzalkonium chloride (BAC) was added to the AXyl 1 _PVA 7 solution and thoroughly stirred overnight. In Method B shown in Fig.1, the arabinoxylan powder was dissolved in 1 N NaOH solution and mixed for 24 hours at room temperature. The PVA was added using the same procedure as in Method A. The composition of the spinning solutions, including type of xylan used, solvent, and content of components have been summarized in Table 1. Table 1 Composition of the solutions used in electrospinning Spinning solution Xylan PVA (wt%) Surfactant (mmol) Type Content (wt%) Solvent Xyl 10 _PVA 7 _w Xylan 10 H 2 O 7 AXyl10_PVA7_w Arabinoxylan 10 H2O 7 AXyl2.5_PVA7_alk Arabinoxylan 2.5 1N NaOH 7 AXyl1_PVA7_alk Arabinoxylan 1 1N NaOH 7 AXyl1_PVA7_alk_BAC Arabinoxylan 1 1N NaOH 7 10 AXyl1_PVA7_w Arabinoxylan 1 H2O 7 AXyl1_PVA7_w_BAC Arabinoxylan 1 H2O 7 10 Fig.1 Schematic representation of preparation procedure of xylan (arabinoxylan, AXyl, and xylan, Xyl) and PVA solutions referred as Methods A and B using two types of solvent: water, and sodium hydroxide, respectively. Cationic surfactant (benzalkonium chloride, BAC) was added in the final stage Analyses applied to characterize spinning solutions Rheological properties of the solutions were measured using Anton Paar Modular Compact Rheometer MCR 302 equipped with concentric cylinder CC27 system at temperature of 20 °C. The pHs and conductivities of the solutions were determined with the multi parameter meter (VWR MU 6100L). The surface tension was measured by the Du Nouy Ring method using a platinum ring and surface tension tester (Krüss GmbH, Hamburg, Germany). Electrospinning Electrospinning was performed using a modular bench top Spinbox instrument (Bioinicia, Valencia, Spain). The distance between nozzle and collector plate was 13 cm, and pumping speed was 0.3 mL/h. The current applied varied from 25 to 12 kV depending on the composition (conductivity) of the electrospun solution. SEM Hitachi SU3500 scanning electron microscope was applied to analysed gold-coated samples. Images were taken at the accelerated voltage of 10 kV using various magnifications: 1000x and 10,000x. Diameters of spun fibres were analysed using ImageJ software. At least 100 fibres were measured to determine the mean diameter and standard deviations. FT-IR analysis A PerkinElmer FT-IR Spectrometer Frontier equipped with ATR sampling accessory was used to acquire spectra of electrospun mats. Spectra were recorded in the range of 4000 to 400 cm -1 at resolution 4 cm -1 . Each spectrum consisted of 10 scanning runs. Contact angle measurements The contact angles of the electrospun mats were measured using a sessile drop test method. The electrospun mat was fixed on the sample glass with double-sided tape in order to obtain as smooth surface as possible. 10 µL of deionised water was placed on the surface of the sample by syringe and three images were immediately taken by camera and handled using CAM 2008 software (KSV instruments, Finland). Out of the three images, the software calculates the contact angles of the water drop on the surface. At least 5 different locations were measured per each mat. Results And Discussion Electrospinning of Xyl 10 _PVA 7 _w and AXyl 10 _PVA 7 _w solutions prepared using Method A In Method A, hot water (80 °C) was used to prepare 10 wt.% xylan (Xyl and AXyl) solutions according to the procedure described by Duan et al. (2019). At 10 wt.% concentration, the beechwood xylan powder was soluble in hot water at 80 °C, whereas the barley husk xylan powder formed a dispersion. Indeed, xylans isolated from biomass are known to have poor solubility in aqueous and aprotic solvents (Jain et al. 2001). PVA concentration of 7 wt.% was chosen based on the preliminary electrospinning trials and easy spinnability at room temperature. Increase in PVA concentration to 10 wt.% resulted in formation of thick gel in the syringe. In general, no disturbances in flow coming from nozzle (so-called, Taylor cone) were observed during spinning of the solution containing beechwood xylan and PVA mixture. The SEM images of the electrospun mat containing beechwood xylan (10 wt%) and PVA (7 wt%) have been shown in Fig. 2. The Xyl 10 _PVA 7 _w electrospun mat had a homogeneous physical appearance. However, SEM images (Fig. 2, left) show that nanofibers were containing inclusions such as local thickenings (knots) and beads. Fig. 2 SEM images of Xyl 10 _PVA 7 _w fibres: magnification 1000x (left) and 10,000x (right) In the case of the AXyl10_PVA7_w solution prepared by Method A, separation of flow coming from the nozzle into white and dark brownish parts became evident immediately after the formation of Taylor cone. More continuous colourless part of the flow resulted in the white or slightly beige mat on the collector plate, which was interrupted by the dark brownish part as shown in Fig. 3. The brownish part flied to collector plate in the form of droplets. Some of these brownish droplets were falling under gravity force in the interspace between nozzle and collector. Several attempts were made to increase the electrostatic force, for example, by increasing voltage and by reducing distance between nozzle and collector plate to minimum. However, it was impossible to overcome the effect of the gravitational force. Fig. 3 Formation of white and brownish parts during electrospinning of AXyl 10 _PVA 7 _w solution The morphology of the AXyl 10 _PVA 7 _w mat was studied using SEM analysis and the images have been shown in Fig. 4. A typical morphology of brownish droplets is indicated with boundary line in Fig. 4 (left) showing as fibreless spot. Instead, the fibrous part of the AXyl 10 _PVA 7 _w electrospun mat was containing inclusions, such as local fiber thickenings and large fiber joints which are visible in Fig. 4 (right). Fig. 4 SEM images of AXyl 10 _PVA 7 _w fibres obtained as different magnifications: 1000x (left) and 10,000x (right) Electrospinning of arabinoxylan/PVA solutions prepared using Method B During electrospinning of the AXyl 10 _PVA 7 _w solution, it was clear that phase separation in PVA-rich phase and hemicellulose-rich phase was taken place. Most probably, the insolubility of arabinoxylan extract in water was the main reason for flow instability. After a careful literature review on electrospinning of hemicelluloses, it was decided to use 1 N NaOH solution to dissolve arabinoxylan and decrease the concentration to 2.5 wt%. While the flow of AXyl 2.5 _PVA 7 _alk solution was improved compared to AXyl 10 _PVA 7 _w solution, the formation of droplets caused by flow instabilities was still noticeable. The electrospun fibres have been shown in Fig. 5. The thickest fibres of the study were spun from AXyl 2.5 _PVA 7 _alk solution (Fig. 5, right). Fig. 5 SEM images of AXyl 2.5 _PVA 7 _alk fibres at magnifications: 1000x (left) and 10,000x (right) In order to improve flow, the further decrease of arabinoxylan content and addition of the cationic surfactant were implemented. SEM images of the electrospun fibres have been shown in Fig. 6. As expected, both decrease in the arabinoxylan concentration and the addition of the cationic surfactant, benzalkonium chloride, resulted in improvement of the flow of the solution used in electrospinning and, simultaneously, the quality of the electrospun mat. Moreover, comparison of mats in Fig. 5 (left) and Fig. 6 (left) and Fig. 7 (left) and results shown in Table 2 revealed that the electrospun mat containing cationic surfactant was composed by the thinner fibres and had the denser structure compared to the others. None of the applied strategies, however, led to the complete disappearance of defects such as beads and local fiber thickenings. Nevertheless, the large fiber joints were not found in mats consisting of AXyl 1 _PVA 7 _alk and AXyl 1 _PVA 7 _alk_BAC. Fig. 6 SEM images of AXyl 1 _PVA 7 _alk fibres at magnifications: 1000x (left) and 10,000x (right) Fig. 7 SEM images of AXyl 1 _PVA 7 _alk_BAC fibres at magnifications: 1000x (left) and 10,000x (right) Electrospinning of AXyl 1 _PVA 7 solutions prepared by Method A with and without surfactant There was also an interest to see if by applying similar strategy, i.e., decrease in hemicellulose concentration (i.e., from originally used 10 wt.% to 1 wt.%) and addition of cationic surfactant will lead to improvements in the case of water-based solution of arabinoxylan. Analysis of SEM images of AXyl 1 _PVA 7 _w and AXyl 1 _PVA 7 _w_BAC mats shown in Fig. 8 and Fig. 9 revealed trends similar to ones found for alkali-dissolved xylan with PVA (AXyl 1 _PVA 7 _alk) and with cationic surfactant (AXyl 1 _PVA 7 _alk_BAC) containing mats. The electrospun mats were more uniform compared to the initial AXyl 10 _PVA 7 _w mat and fibres were finer. Somehow, the exchange of alkali to water led to the denser structure of the resulting mat. Fig. 8 SEM images of electrospun AXyl 1 _PVA 7 _w mats without cationic surfactant: 1000x (left) and 10,000x (right) Fig. 9 SEM images of electrospun AXyl 1 _PVA 7 _w mats with cationic surfactant: 1000x (left) and 10,000x (right) Size of electrospun fibres Average diameters of the fibres in the structure of the electrospun mats were calculated using Image J software and the results have been presented in Table 2. Results shown in the Table 2 are average of calculations made for 100 fibres per each type of mat. The 7% aqueous solution of PVA spun at pumping rate of 0.3 mL/h, distance of 13 cm, voltage of 20 kV was used as a reference. From Table 2 it is evident that solution containing xylan extracted from beechwood, Xyl 10 _PVA 7 _w, resulted in finer fibers than solution containing arabinoxylan extracted from barley husks, AXyl 10 _PVA 7 _w. Operating conditions during spinning were identical for both types of xylan. Similarity between fibre size of PVA 7 _w and AXyl 10 _PVA 7 _w mats and flow (phase) separation observed in the case of the AXyl 10 _PVA 7 _w solution electrospinning can indicate that the fiber mat consisted mostly of PVA while arabinoxylan was disposed as droplets. Chemical composition of the two phases and the results of the FTIR analysis of the mats will be discussed in the following section. Generally, the mats spun from the aqueous solutions had thinner fibres than their analogues spun from the alkaline solutions. Moreover, both the decrease in concentration of arabinoxylan from 2.5 to 1.0 wt.% and use of cationic surfactant resulted in thinner fibers. More specifically, the 42% decline in the fiber diameter was calculated after addition of cationic surfactant to AXyl 1 _PVA 7 _w solution. Table 2 Calculated diameters and defects of fibres Sample Diameter of fibres (nm) Size of defects (nm) PVA 7 _w 148.0 ± 39.2 > 300 Xyl 10 _PVA 7 _w 100.5 ± 39.5 300 AXyl 2.5 _PVA 7 _alk 212.3 ± 55.7 > 300 AXyl 1 _PVA 7 _alk 156.3 ± 43.0 > 300 AXyl 1 _PVA 7 _alk_BAC 121.2 ± 36.5 > 200 AXyl 1 _PVA 7 _w 130.5 ± 35.0 200 Characterisation of electrospinning solutions The appearance of the fibres collected depended on many factors (Jarusuwannapoom et al. 2005). One of them is the viscoelastic force, which depends on the concentration of the solution, average molecular weight of the polymer, viscosity, and surface tension of the solution. Another on is the gravitational force which depends on the density and the conductivity of the solution and electrostatic forces. Recognising this, conductivity, viscosity, and surface tension of solutions were measured, and results have been shown in Table 3. The solution conductivity is known to be one of the main parameters in the electrospinning process since the viscous polymer solution is stretched due to repulsion of the charges present on its surface. As expected, presence of sodium hydroxide drastically increased the conductivity of the solutions. Increased conductivity resulted in decrease of voltage at which Taylor cone is formed (e.g., voltage decreased from 25 to 20 kV for the AXyl 1 _PVA 7 _w and AXyl 1 _PVA 7 _alk solution, respectively). However, high conductivity is not always guarantee spinnability of the solution. For example, solution of AXyl 10 _PVA 7 _w had higher conductivity than AXyl 1 _PVA 7 _w solution but its spinnability was problematic due to extremely high viscosity. Viscosity curves of the solutions as a function of shear stress including 10 and 1 wt.% AXyl_w, 2.5 and 1 wt.% AXyl_alk and 7 wt.% PVA, are shown in Fig. 10. Table 3 pH, conductivity, shear viscosity and surface tension of the xylan_PVA solutions Sample pH Conductivity (mS/cm) Shear viscosity 1 (Pa·s) Surface tension, γ (mN/m) Xyl 10 _PVA 7 _w 7.9 2.53 2.03 > 80 AXyl 10 _PVA 7 _w 8.7 1.29 11.33 55.3 AXyl 2.5 _PVA 7 _alk 13.3 54.10 0.55 42.8 AXyl 1 _PVA 7 _alk 13.2 57.37 0.25 41.9 AXyl 1 _PVA 7 _alk_BAC 13.1 57.00 0.31 37.5 AXyl 1 _PVA 7 _w 7.0 0.63 0.12 49.0 AXyl 1 _PVA 7 _w_BAC 6.5 1.17 0.11 37.0 shear viscosity was determined at shear rate of 50 1/s Both xylans used, beech (Xyl) and barley husk (AXyl), contains of 4-O-methyl-glucuronic acids (Köhnke et al. 2009, Teleman et al. 2002), and, thus, they are negatively charged in aqueous solutions. Dissolution of the negatively charged groups is highly dependent on pH (Sjöström 1989). In the solutions studied (Table 3), these uronic acid groups are known to be fully dissociated at pH 6-8.5. At higher pH values when pH exceeds 12, also carbonyls and phenolic hydroxyl groups have been fully dissociated. According to manufacturer, arabinoxylan of barley husk contains lignin (Klason lignin 19.6%) bound to xylan, thus, it contains these phenolic hydroxyl groups. At pH 13, only small amount of hydroxyl groups in alcohols have reported to be dissociated (Sjöström 1989). Comparison of conductivity of AXyl 10 _PVA 7 _w and Xyl 10 _PVA 7 _w solutions shown in Table 3 indicates that Xyl contains higher charge (higher amount of 4-O-methyl glucuronic acid) compared to AXyl. In Table 3, increase of the pH up to 13 shows clearly that conductivity increase drastically showing increase of Na + an OH - ions and possible increase of the dissociating groups. When cationic surfactant, i.e. benzalkonium chloride, is added, complexation of charges between xylan and surfactant is evident. The driving force for the complexation between oppositely charged polyelectrolytes and surfactants are electrostatic and hydrophobic forces (Holmberg et al. 2002). The head groups of the surfactant molecules are attracted by the charged polymer segments, and also the hydrophobic surfactant tails can interact with the hydrophobic backbone of the polyelectrolytes, such as lignin attached to xylan in AXyl. According to Table 3, surface tension of the solutions decreases from 41.9 to 37.5 (pH 13) and 49.0 to 37.0 (pH 6.5), respectively. Concentration of 10 mM for cationic surfactant (BAC) was used in the solutions, which is higher than the critical micelle concentration (CMC) of BAC reported, 3 mM (Turku and Sainio 2009). Schematic plot of the concentration dependence of the surface tension for mixed polymer solution described by Holmberg et al. (2002) shows that in the concentration of benzalkonium chloride used in the studies, CMC and critical association concentration CAC have been reach and micelles of surfactant have been formed, seen as lowered surface tension values of the solutions. Maximum effectiveness of benzalkonium chloride have been reported to exist between pH 4-10 (Handbook of Pharmaceutical Excipients 2006), indicating that the at pH 13 the quaternary ammonium compounds are not fully dissociated. Because PVA is also present in the solutions, the behavior of surfactant-polymer aggregations becomes more complex, which needs to be studied further. Fig. 10 Viscosity as a function of shear rate curves As shown in Fig. 10, most of the solutions tested demonstrated a shear-thinning behaviour indicating that the viscosity decreases with applied shear. Among all studied solutions, 7 wt.% PVA showed behaviour close to Newtonian in wide range of shear stresses. As was discussed earlier, 7 wt.% PVA solution was easily spinnable at ambient temperature. Thus, electrospinning solutions having viscosities close to viscosity of pure PVA 0.08 Pa·s (e.g, AXyl 1 _PVA 7 _w and AXyl 1 _PVA 7 _alk with and without surfactant) had good spinnability. It was not shown here, but rheological measurements for AXyl 10 _PVA 7 _w and AXyl 2.5 _PVA 7 _alk solutions made at higher temperatures (i.e., 50 and 80 °C) resulted in significant reduction of their viscosities. Reduction of solution viscosity is considered as an efficient way to improve its spinnability. Xyl 10 _PVA 7 _w solution had lower viscosity than AXyl 10 _PVA 7 _w solution (Table 3 and Fig.10). Since equal amount of PVA was used in both cases, the difference was connected to the nature of xylan. Both chemical composition and molecular mass of xylan can be a reason for that. Molar mass of xylan extracted from beechwood is lower than molar mass of arabinoxylan extracted from barley husk. Chemical compositions of xylan and arabinoxylan extracts will be discussed later. Mixing of PVA with AXyl resulted in an increased viscosity. This effect was independent on the concentration or alkalinity of the AXyl solution. Increase in the viscosity of two-component mixture may signify the polymer’s interactions (or formation of larger particulates). Lignin is supposed to be closely bound (in non-dissociated complex) to arabinoxylan in aqueous dispersion of barley husk extract. Indeed, a single step extraction, which commonly has been used to isolate xylan from barley husks (Glasser et al. 2000) resulted in xylan entrapped with lignin. Three types of linkages are known to exist between lignin and polysaccharides in lignin-carbohydrate complexes (LCC), i.e., benzyl ester-, benzyl ether- and glycosidic linkage (Lai 1991). Addition of PVA to arabinoxylan-lignin complex caused formation of hydrogen bonds between hydroxyl groups of PVA and arabinoxylan-lignin molecules, and as a consequence, increased the viscosity. At neutral pH (7.0), phenolic hydroxyl groups of lignin are not fully dissociated and thus cannot participate into formation of bonds between PVA and arabinoxylan-lignin complex. This could be one explanation why viscosity of AXyl 1 _PVA 7 _w solution is lower than viscosity of AXyl 1 _PVA 7 _alk solution (0.12 v’s 0.25 Pa·s). Increase in viscosity was found also in the case of addition of surfactant to alkaline AXyl 1 _PVA 7 solution. A strong polymer-surfactant interaction could alter the rheological properties of the polymer solution, e.g., if the polymer can associate with the surfactants (Lin et al. 2004). In alkaline AXyl 1 _PVA 7 solution, an addition of cationic surfactant is assumed helping to form large associates between positively charged micelles of surfactant and negatively charged groups of arabinoxylan and lignin. It was very interesting to note a difference in effects caused by surfactant on viscosities of AXyl 1 _PVA 7 _w and AXyl 1 _PVA 7 _alk solutions. Viscosity of AXyl 1 _PVA 7 _w_BAC solution was lower compared to the AXyl 1 _PVA 7 _w solution, in contrast to AXyl 1 _PVA 7 _alk_BAC solution. The difference can be explained by the difference in the dissolution state and by the charge of the arabinoxylan in pH-neutral and alkaline solutions. Most probably, at neutral pH there was not enough anionic groups in arabinoxylan/lignin-PVA complex available to participate into electrostatic interactions with benzalkonium cations associated in micelles. Formation of free micelles non-bound electrostatically to the polymer backbone, can be responsible for decrease in viscosity in the case of AXyl 1 _PVA 7 _w_BAC solution. However, this question requires more detailed study. Surface tension of the solution is the factor, which can affect the spinnability. According to the Taylor equation, there is a relationship between voltage applied and the surface tension of the solution: where V c is the critical electrical voltage, H is the separation between the tip of nozzle (capillary) and collector plate, L is the length of the capillary, R is the radius of the capillary and γ is the surface tension of the solution (Yao et al. 2003). Voltage required to obtain a stable Taylor cone in a solution with or without cationic surfactant at the same working distance and pumping feed rate was noticeable different. Addition of cationic surfactant reduced clearly the surface tension of AXyl 1 _PVA 7 _alk and AXyl 1 _PVA 7 _w on 10.5 and 24.5% (Table 3), respectively, and, as consequence, resulted in lower applied voltage. There is a strong connection between polymer concentration and thickness of fibres. As was discussed earlier, the average thickness of AXyl 2.5 _PVA 7 _alk fibres was higher than thickness of AXyl 1 _PVA 7 _alk fibres (212.3 ± 55.7 v’s 156.3 ± 43.0 nm) (Table 2). The decrease in thickness of fibres with the decrease of polymer concentration was previously described by researchers using polystyrene (Uyar and Besenbacher 2008; Lee et al. 2003). Most often, high polymer concentration means higher viscosity. According to the studies on polystyrene, the high polymer concentrations is prerequisite for formation of stable jet during electrospinning. Stable jet should reduce the number of beads (defects) significantly. As stated earlier, the spinnability of AXyl_PVA 7 system with increase of arabinoxylan concentration was impossible due to too high viscosity of the solution. Based on the results of this work, it is preferred to increase the concentration of polymers and use of higher temperatures to improve the spinnability of solution and to obtain defect-free fibres. Chemical composition of nanofibrous mats The FT-IR spectroscopy was used to assess the chemical composition of the electrospun mats, and the spectra have been presented in Fig. 11. In order to interpret the FT-IR spectra of the electrospun mats, the spectra of pure powders of PVA, arabinoxylan extracted from barley husk and xylan extracted from beechwood were measured and peak assignments have been shown in Table 4. Table 4 The main bands identified on FT-IR spectra of Xyl, AXyl and PVA powders Wavenumbers for Xyl (cm -1 ) Wavenumbers for AXyl (cm -1 ) Wavenumbers for PVA (cm -1 ) 987 987 916 1041 1035 1086 1160 1160 1142 1250 1252 1238 1377 1377 1378 1408 1414 1418 1510 1603 1595 1650 2919 2919 2940 3343 3341 3272 Following conclusions were drawn based on data shown in Table 4. First, the main difference between spectra of xylan and arabinoxylan is absence of peaks at 1510 and 1595 cm -1 which can be assigned to the aromatic skeletal vibrations of lignin residue (Sun et al. 2005). Second, the common features for xylan and arabinoxylan are peaks associated with xylopyranose backbone: peak at 1035 – 1041 cm -1 , which is attributed to the C – O stretching, peaks at 2919 cm -1 and 3341 – 3343 cm -1 assigned to C – H and O – H stretching, respectively (Duan et al. 2019). The peak at 1035 – 1041 cm -1 in xylans has two shoulders at 1160 and 987 cm -1 of low-intensity. The peak at 1603 cm -1 in xylan spectra can be explained by absorbed water. In general, the spectra of xylans and PVA are close to each other, for example the peaks 1377 – 1378, 1414 – 1418 and 1252 - 1238 cm -1 corresponding to the C – H and C – O stretching and bending vibrations in xylans and PVA molecules (Sun et al. 2005, Bary et al. 2019). The characteristic peak of PVA at 1086 cm -1 has shoulder at 1142 cm -1 , which determines polymer crystallinity (Mallapragada et al. 1996, Tretinnikov et al. 2012). There are differences between the xylan and PVA peaks obtained in region above 2000 cm -1 . The peaks at 3272 and 2940 cm -1 correspond to O – H and C – H stretching of PVA, respectively. Fig. 11 FT-IR spectra of studied electrospun mats and reference components: PVA, xylan and arabinoxylan powders. Analysis of spectra of AXyl 10 _PVA 7 _w droplets and fibres showed that fibres had more pronounced peak at 1083 cm -1 that is closer to the characteristic peak of PVA, while droplets had more pronounced peak at 1039 cm -1 and no peak at 1083 cm -1 . Use of alkaline for arabinoxylan dissolution caused the formation of the peaks at 1434 and 1565-1574 cm -1 . They are considered as shifts from peaks with original positions 1421 and 1595 cm -1 which corresponds to aromatic skeletal vibrations. It is known that in an alkaline solution, ionization of the phenolic hydroxyl groups is responsible for the shifts of the phenolic absorption bands of compounds (Morohoshi 1991). The arabinoxylan extract from barley husks contained 19.6 % of Klason lignin. Lignin was thought to be a reason why AXyl formed the dispersion in water. Addition of surfactant to the AXyl 1 _PVA 7 _w and AXyl 1 _PVA 7 _alk solutions was appeared as a sharp peak at 2855 cm -1 , which is typical for benzalkonium chloride. Hydrophilicity of electrospun mats Contact angles of the electrospun mats as a function of composition has been shown in Table 5, where the mean values and standard deviations have been calculated out of 15 (3x5) measurements. Two-sample t-test and Tukey’s simultaneous test were applied to determine if changes in contact angle from the PVA 7 _w was statistically significant at P-value less than 0.05. Table 5 Contact angles of electrospun mats Sample Contact angle (°) Trend PVA 7 _w 46.9 ± 8.4 Reference Xyl 10 _PVA 7 _w 30.2 ± 5.1 ↓ (S) AXyl 10 _PVA 7 _w 54.3 ± 6.2 ↑ (NS) AXyl 1 _PVA 7 _w 48.1 ± 2.2 ↑ (NS) AXyl 1 _PVA 7 _alk 18.0 ± 3.0 ↓ (S) S corresponds to significant change (at probability level 0.05), NS corresponds to non-significant change (at probability level 0.05), and arrows show the trends (↑ corresponds to improvements and ↓ corresponds to decline). The contact angle measurements are very sensitive to roughness and porosity of surface. The difference in microstructure of spun mats can be assessed from SEM images presented in earlier section. As can be seen, equal times (means equal fused volumes) of spinning was not warranty that fibre mats produced had similar microstructure (i.e., porosity). As can be seen from Table 5, the contact angle of Xyl 10 _PVA 7 _w mat was significantly lower than the contact angle of PVA 7 _w and AXyl 10 _PVA7_w mats. Hydrophilic nature of former mat can be explained by hydrophilicity of beechwood xylan. Presence of lignin in extract of arabinoxylan can explain its higher hydrophobicity. Decrease in content of arabinoxylan extract (from 10 to 1 wt%) and consequently in lignin concentration led to predictable decrease in hydrophobicity of mat. Usage of alkaline for arabinoxylan dissolution led to formation of highly hydrophilic mats. This hydrophilicity is in a good agreement with results of FTIR analysis which revealed ionization of the phenolic hydroxyl groups of lignin at alkaline conditions. Conclusion This study was focused on the spinnability of arabinoxylan extracted from barley husk. Two different solvents were applied to produce the spinning solutions. It was found that alkaline conditions were required for solubilization of the arabinoxylan extract. Among other components of arabinoxylan extract, lignin is believed to be a major one to determine solubility of this extract. In contrast to arabinoxylan extract, the extract of xylan obtained from beechwood was easily soluble in hot water. Lower viscosity and improved spinnability of Xyl 10 _PVA 7 _w compared to AXyl 10 _PVA 7 _w solution was explained by presence of lignin in arabinoxylan. In addition, lignin is found to be responsible for increased hydrophobicity of AXyl 10 _PVA 7 _w nanofibrous mats. In future studies, usage of the lignin-rich solution to improve water resistance of the PVA-based nanofibrous mats can be used. However, as can be seen in the cases of AXyl 1 _PVA 7 _w and AXyl 1 _PVA 7 _alk mats, the solvent nature could also drastically change hydrophilicity of mats obtained. From rheological measurements, it became clear that type of solvent was a limiting factor affecting the interaction between polymers (i.e., PVA and arabinoxylan/lignin) and surfactants. However, more work is needed to understand the interactions between molecules and molecular structure of the nanofibrous mats. The materials electrospun in this study as composed of 75-200 nm fibres have potential application in the fields, where high aspect ratio (or high surface area) of fibres is required (e.g., air filtration). However, their performance should be further studied. Declarations Acknowledgements This study was supported by the Business Finland funded BioProt Co-creation project (1.7.2020-28.2.2021), which aimed on development of bio-based and biodegradable nonwoven materials from forest industry and use as protective equipment. Authors are thankful to Prof. Kristiina Oksman and Dr. Linn Berglund from the Laboratory of Wood and Bionanocomposites, Luleå, Sweden for supply of arabinoxylan extract. Funding This study was mainly supported by the Business Finland funded BioProt Co-creation project (1.7.2020-28.2.2021), which aimed on development of bio-based and biodegradable nonwoven materials from forest industry and use as protective equipment. Additional funding was obtained as a grant awarded by Etelä-Karjalan Säästöpankkisäätiö to Dr. Katri Laatikainen. Conflict of interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. 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Chem Mater 15:1860-1864. https://doi.org/10.1021/cm0210795 Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Major revisions 22 Feb, 2022 Reviews received at journal 09 Jan, 2022 Reviewers invited by journal 06 Jan, 2022 Editor invited by journal 01 Jan, 2022 Editor assigned by journal 29 Dec, 2021 First submitted to journal 27 Dec, 2021 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-1210254","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":74841242,"identity":"21929f47-ad89-4755-b01f-a3b53886a18e","order_by":0,"name":"Svetlana Butylina","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABAklEQVRIiWNgGAWjYLCCByBCAkQUAEn25gYgS44HjwbGhgSIFsYGBgOgFp6DDQwHGIyJ1gJiJIK14FQvPyP5+IOEmjvyDNI95o95DCzy+Gc+bJP+wGAgg0uLwY20xIaEY88MG2TOGDbzGEgUS9xObJM4wGCA02EGPGcMGxLYDjM2SOSAtSQ2QLT8walFvuf8x4aEf4ft4Vrm3zyI3xaG4z2MDYlthxPhWjbcYCTgsONthjMS+w4nt8kcK5w5B6hl45nEZoszBri1yDczP/jw4dth237p5g0f3lTUJc47fvjgjYoKA3ucDoMBNiBmQphsQFADBDD+IFLhKBgFo2AUjCwAANq6Wm6RjiZfAAAAAElFTkSuQmCC","orcid":"https://orcid.org/0000-0002-7282-9841","institution":"LUT University","correspondingAuthor":true,"prefix":"","firstName":"Svetlana","middleName":"","lastName":"Butylina","suffix":""},{"id":74841243,"identity":"f9455d7b-f3ad-4520-b1e7-53844c4855e4","order_by":1,"name":"Krista Koljonen","email":"","orcid":"","institution":"LUT University","correspondingAuthor":false,"prefix":"","firstName":"Krista","middleName":"","lastName":"Koljonen","suffix":""},{"id":74841244,"identity":"53508cd9-31ef-482b-aa77-048d05de1fa2","order_by":2,"name":"Salla Hiltunen","email":"","orcid":"","institution":"UPM-Kymmene Oyj: UPM","correspondingAuthor":false,"prefix":"","firstName":"Salla","middleName":"","lastName":"Hiltunen","suffix":""},{"id":74841245,"identity":"8f18c076-6ed9-443e-b985-2fcf36a6cbff","order_by":3,"name":"Katri Laatikainen","email":"","orcid":"","institution":"LUT-yliopisto: LUT University","correspondingAuthor":false,"prefix":"","firstName":"Katri","middleName":"","lastName":"Laatikainen","suffix":""}],"badges":[],"createdAt":"2021-12-28 09:40:04","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-1210254/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-1210254/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":17168819,"identity":"2b4e8a0c-f0cf-47a9-91c0-caba37738266","added_by":"auto","created_at":"2022-01-10 15:51:17","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":61447,"visible":true,"origin":"","legend":"\u003cp\u003eSchematic representation of preparation procedure of xylan (arabinoxylan, AXyl, and xylan, Xyl) and PVA solutions referred as Methods A and B using two types of solvent: water, and sodium hydroxide, respectively. 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3","display":"","copyAsset":false,"role":"figure","size":519941,"visible":true,"origin":"","legend":"\u003cp\u003eFormation of white and brownish parts during electrospinning of AXyl\u003csub\u003e10\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w solution\u003c/p\u003e","description":"","filename":"3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-1210254/v1/600d44f2f514310ecaff7ecb.jpg"},{"id":17168807,"identity":"7a46bcaa-5d75-4a6f-af93-e224d7b97d4b","added_by":"auto","created_at":"2022-01-10 15:50:53","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":1119290,"visible":true,"origin":"","legend":"\u003cp\u003eSEM images of AXyl\u003csub\u003e10\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w fibres obtained as different magnifications: 1000x (left) and 10,000x (right)\u003c/p\u003e","description":"","filename":"4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-1210254/v1/4e53837e2e900a2b11920b7b.jpg"},{"id":17168817,"identity":"9612ee9f-01f4-432d-8756-58fa16a3f5e2","added_by":"auto","created_at":"2022-01-10 15:51:13","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":1044249,"visible":true,"origin":"","legend":"\u003cp\u003eSEM images of AXyl\u003csub\u003e2.5\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_alk fibres at magnifications: 1000x (left) and 10,000x (right)\u003c/p\u003e","description":"","filename":"5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-1210254/v1/bc2ee1a94d6870ff62e94f99.jpg"},{"id":17168816,"identity":"13bf55f9-47ab-454f-8a73-a4360be717ff","added_by":"auto","created_at":"2022-01-10 15:51:09","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":1090267,"visible":true,"origin":"","legend":"\u003cp\u003eSEM images of AXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_alk fibres at magnifications: 1000x (left) and 10,000x (right)\u003c/p\u003e","description":"","filename":"6.jpg","url":"https://assets-eu.researchsquare.com/files/rs-1210254/v1/4ffe3f75694fd1e568ad091a.jpg"},{"id":17168791,"identity":"474c235c-69af-4186-b81f-156e9194a860","added_by":"auto","created_at":"2022-01-10 15:49:53","extension":"jpg","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":1023906,"visible":true,"origin":"","legend":"\u003cp\u003eSEM images of AXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_alk_BAC fibres at magnifications: 1000x (left) and 10,000x (right)\u003c/p\u003e","description":"","filename":"7.jpg","url":"https://assets-eu.researchsquare.com/files/rs-1210254/v1/c99ac5dbf229adc09d500ffc.jpg"},{"id":17168812,"identity":"f4de1f1d-4e41-4393-8829-5d535e04c8f6","added_by":"auto","created_at":"2022-01-10 15:51:03","extension":"jpg","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":1128731,"visible":true,"origin":"","legend":"\u003cp\u003eSEM images of electrospun AXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w mats without cationic surfactant: 1000x (left) and 10,000x (right)\u003c/p\u003e","description":"","filename":"8.jpg","url":"https://assets-eu.researchsquare.com/files/rs-1210254/v1/bb93803a28867e86a3f9540a.jpg"},{"id":17168829,"identity":"2b827975-c85f-41b8-8906-2409d96f87f3","added_by":"auto","created_at":"2022-01-10 15:51:20","extension":"jpg","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":1495371,"visible":true,"origin":"","legend":"\u003cp\u003eSEM images of electrospun AXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w mats with cationic surfactant: 1000x (left) and 10,000x (right)\u003c/p\u003e","description":"","filename":"9.jpg","url":"https://assets-eu.researchsquare.com/files/rs-1210254/v1/482d464257cea525eb4bf1f7.jpg"},{"id":17168813,"identity":"531a863b-20c1-4434-932a-a22b24dd3940","added_by":"auto","created_at":"2022-01-10 15:51:05","extension":"jpg","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":95486,"visible":true,"origin":"","legend":"\u003cp\u003eViscosity as a function of shear rate curves\u003c/p\u003e","description":"","filename":"10.jpg","url":"https://assets-eu.researchsquare.com/files/rs-1210254/v1/c31daf517d7fd4b5fb8b258c.jpg"},{"id":17168815,"identity":"77fba761-edba-40b2-a4c3-55bccd3f2239","added_by":"auto","created_at":"2022-01-10 15:51:09","extension":"jpg","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":96134,"visible":true,"origin":"","legend":"\u003cp\u003eFT-IR spectra of studied electrospun mats and reference components: PVA, xylan and arabinoxylan powders.\u003c/p\u003e","description":"","filename":"11.jpg","url":"https://assets-eu.researchsquare.com/files/rs-1210254/v1/84ef5f6a480edd7429e59e69.jpg"},{"id":17168889,"identity":"94bce6d7-00aa-4424-8f69-5fd92a5f03f3","added_by":"auto","created_at":"2022-01-10 15:52:54","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1101258,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-1210254/v1/8c271b78-2754-4d9a-b852-0cc8ab1d4e2f.pdf"}],"financialInterests":"","formattedTitle":"\u003cp\u003eStudy on Spinnability of Arabinoxylan Extracted From Barley Husks\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003eCircular economy has increased the usage of the biopolymers derived from various side streams and industrial waste materials both in agriculture and wood processing. The importance of circular economy in the fight against microplastic and carbon dioxide emissions has been well acknowledged in recent years (Forni \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). Biopolymers originated from industrial and agricultural side streams can be divided into three groups such as polysaccharides (cellulose, hemicellulose, starch, chitin), proteins (silk, collagen) and phenol-based polymer lignin (Moohan et al. \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2019\u003c/span\u003e). Hemicelluloses are of specific interest because they represent second most abundant group of biopolymers after cellulose and represent 30-40% of agricultural residues (Sun et al. \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2011\u003c/span\u003e), but compared to cellulose is being barely utilized as raw material (Peng et al. 2014). Among all types of hemicelluloses, xylans are the most abundant type, which can be further divided into subclasses: homoxylans, glucuronoxylans, (arabino)glucuronoxylans, arabinoxylans, (glucurono)arabinoxylans and heteroxylans (Ebringerov\u0026aacute; \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2006\u003c/span\u003e). The fractionation and purification of some specific xylans from plant-based materials is complicated, costly, and time-consuming process (Ferrari et al. \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). Use of crude (non-refined) xylan-containing extracts wherever it is possible can significantly reduce the cost of product.\u003c/p\u003e \u003cp\u003eIncreased interest in barley husks can be explained by significance of barley (\u003cem\u003eHordeum vulgare\u003c/em\u003e) as crop plant. Finland produces barley in amount of 1,4 million tons per year (Luke 2020), whereas worldwide annual production is 160 million tons (FAO 2019). Husk is the outermost layer of the grain which forms 10\u0026ndash;20% of the grain weight (Holopainen- Mantila 2015; Bhardwaj et al. \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2020\u003c/span\u003e) and a side-stream waste material from the manufacture of starch and ethanol (K\u0026ouml;hnke et al. \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2009\u003c/span\u003e). Traditionally, barley husk is peeled off and burned. Extraction method used can affect chemical composition of barley husk material (H\u0026ouml;ije et al. \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2005\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2006\u003c/span\u003e; B\u0026ouml;rjesson 2018), however, mostly it consists of hemicelluloses, i.e. arabinoxylan, and cellulose with smaller amounts of lignin, protein, starch and fat. Recently, possibilities to exploit the fractions of barley husk in high-value product for different applications have been studied. L\u0026auml;hde et al. (\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2020\u003c/span\u003e) has described synthesis of nanostructured silicon carbide and graphene-like carbon from the silica extracted from barley husk. The transformation of cellulose fraction of barley husk into nanocellulose by sulphuric acid hydrolysis was studied by B\u0026ouml;rjesson et al. (\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). H\u0026ouml;ije et al. (\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2005\u003c/span\u003e) have published research on development of oxygen barrier coatings from arabinoxylans extracted of barley husks. Berglund et al. (\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2018\u003c/span\u003e) have studied the formation of composite aerogels from lignin-containing arabinoxylan and cellulose nanofibers which could be applied in the soft tissue engineering.\u003c/p\u003e \u003cp\u003eElectrospinning is a distinguished method for the preparation of nanofibers consisting of dissolved or melt polymers and biopolymers or their blends (Frenot and Chronakis \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2003\u003c/span\u003e; Subbiah et al. \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e2005\u003c/span\u003e; Agarwal et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2009\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2016\u003c/span\u003e). In electrospinning process, a polymer solution or melt is placed into a syringe with a millimeter-size nozzle and is subjected to high electric field. Under the applied electrostatic force, the polymer is ejected from the nozzle and transported and deposited on a collector, which also serves as the ground for the electrical charges. Electrospun fibers have been widely used in several applications including scaffolds for tissue engineering, drug delivery, medical implants, biosensors, wound dressing (Rogina \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e2014\u003c/span\u003e), water filtration and packaging materials (Torres-Giner et al. \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). Usually, the electrospun fibers have unique properties, such as high surface area-to-volume ratio, high pore interconnectivity and easy surface functionalization.\u003c/p\u003e \u003cp\u003eSeveral studies have been published on spinnability of various xylans. Krishnan et al. (\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2012\u003c/span\u003e) and Venugopal et al. (\u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e2013\u003c/span\u003e) have studied the beech-wood derived glucuronoxylan and Duan et al. (\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2019\u003c/span\u003e) have electrospun the arabinoglucuronoxylan extracted from straw fibres. In these studies, different solvents were used: 1N sodium hydroxide and hot water, respectively. Most often, poly(vinyl alcohol) (PVA) and poly(ethylene oxide) (PEO) have been used to ensure the adequate entanglements and to facilitate the electrospinning of the xylan solutions. Due to the excellent properties of PVA, such as water-solubility, non-toxicity, biodegradability, it has been widely used in different nanofiber composite materials, for example, together with nanoclay (Ristolainen et al. \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2006\u003c/span\u003e), chitosan (Park et al. \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2009\u003c/span\u003e), aloe vera (Abdullah et al. 2014) and graphene oxide (Wang et al. \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e2012\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eLimited dispersion and solubilization of biopolymers are factors which make their electrospinning process challenging (Peresin and Rojas \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). It has been shown in numerous studies (Ebringerov\u0026aacute; and Heinze 2000; Ebringerov\u0026aacute; \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2006\u003c/span\u003e; Glasser et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2000\u003c/span\u003e; Roos et al. \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2009\u003c/span\u003e) that solubility of xylans and their rheological behaviour depend on their plant origin, molecular structure, and method of extraction. Therefore, solubility is one of the subjects which will be addressed in the present study.\u003c/p\u003e \u003cp\u003eIn this work the spinnability of arabinoxylan extract from barley husks was studied concentrating especially on the effects of alkaline, concentration of arabinoxylan extract and surfactant addition. The properties of the electrospinning solution were determined and connected with the properties of the electrospun materials. The xylan from beechwood was used as a reference. The quality of fibres was assessed by scanning electron microscopy and their chemistry was studied by FTIR spectroscopy and contact angle measurements.\u003c/p\u003e"},{"header":"Materials And Methods","content":"\u003cp\u003eMaterial\u003c/p\u003e\n\u003cp\u003eThe commercial grade poly (vinyl alcohol), PVA (Aldrich Chemistry), had a molecular weight of 89-98 kg/mol and 99% degree of hydrolysis. Arabinoxylan (AXyl) (Xylophane AB, Gothenburg, Sweden) was an extract from barley husk. According to the manufacturer specification, the sugar composition of this extract consisted of xylose (48.5%), arabinose (11.7%) and glucose (3.8%). The non-hemicellulose components of extract consisted of Klason lignin (19.6%), fat (4.2%), ash (4.3%) protein (6.8%) and starch (less than 1%). European beechwood xylan was pharmaceutical grade (Iris Biotech GmbH) consisting of poly(beta-D-xylopyranose [1\u0026rarr;4]) linkages. Both, the barley husk xylan and the beechwood xylan were used without further treatment. Benzalkonium chloride, BAC, (Fluka \u0026ge; 95.0%) was used as a cationic surfactant. It contained H\u003csub\u003e2\u003c/sub\u003eO \u0026le; 10% and ash as SO\u003csub\u003e4\u003c/sub\u003e \u0026le; 0.1% and was a mixture of 60% C\u003csub\u003e12\u003c/sub\u003e and 40% C\u003csub\u003e14\u003c/sub\u003e homologues. The average molar mass of BAC was 350 g/mol and critical micelle concentration (CMC) was 3 mM determined in 0.1 mM NaCl (Turku and Sainio 2009).\u003c/p\u003e\n\u003cp\u003eMethods\u003c/p\u003e\n\u003cp\u003ePreparation of spinning solutions\u003c/p\u003e\n\u003cp\u003eTwo types of approach were used to dissolve xylan, referred in this study as Method A and B. In the Method A described by Duan et al. (2019), the xylan powder is dissolved in water under vigorous magnetic stirring at 80 \u0026deg;C for 24 hours in tightly sealed flask as illustrated in Figure 1. Thereafter, the PVA powder was added into prepared solution and heated at 80 \u0026deg;C under stirring at 500 rpm for 3 hours to complete the dissolution of PVA followed by the overnight stirring without heating. The 10 mmol of cationic surfactant, benzalkonium chloride (BAC) was added to the AXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e solution and thoroughly stirred overnight.\u003c/p\u003e\n\u003cp\u003eIn Method B shown in Fig.1, the arabinoxylan powder was dissolved in 1 N NaOH solution and mixed for 24 hours at room temperature. The PVA was added using the same procedure as in Method A. The composition of the spinning solutions, including type of xylan used, solvent, and content of components have been summarized in Table 1.\u003c/p\u003e\n\u003cp\u003eTable 1 Composition of the solutions used in electrospinning\u003c/p\u003e\n\u003ctable border=\"1\" cellpadding=\"0\" cellspacing=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" width=\"24.27843803056027%\"\u003e\n \u003cp\u003eSpinning solution\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" valign=\"top\" width=\"37.521222410865875%\"\u003e\n \u003cp\u003eXylan\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" width=\"16.97792869269949%\"\u003e\n \u003cp\u003ePVA (wt%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" width=\"21.222410865874362%\"\u003e\n \u003cp\u003eSurfactant (mmol)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"39.63963963963964%\"\u003e\n \u003cp\u003eType\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"25.675675675675677%\"\u003e\n \u003cp\u003eContent (wt%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"34.68468468468468%\"\u003e\n \u003cp\u003eSolvent\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"24.23728813559322%\"\u003e\n \u003cp\u003eXyl\u003csub\u003e10\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"14.915254237288135%\"\u003e\n \u003cp\u003eXylan\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"9.661016949152541%\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"13.05084745762712%\"\u003e\n \u003cp\u003eH\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"16.949152542372882%\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.1864406779661%\"\u003e\n \n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"24.23728813559322%\"\u003e\n \u003cp\u003eAXyl\u003csub\u003e10\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"14.915254237288135%\"\u003e\n \u003cp\u003eArabinoxylan\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"9.661016949152541%\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"13.05084745762712%\"\u003e\n \u003cp\u003eH\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"16.949152542372882%\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.1864406779661%\"\u003e\n \n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"24.23728813559322%\"\u003e\n \u003cp\u003eAXyl\u003csub\u003e2.5\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_alk\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"14.915254237288135%\"\u003e\n \u003cp\u003eArabinoxylan\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"9.661016949152541%\"\u003e\n \u003cp\u003e2.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"13.05084745762712%\"\u003e\n \u003cp\u003e1N NaOH\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"16.949152542372882%\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.1864406779661%\"\u003e\n \n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"24.23728813559322%\"\u003e\n \u003cp\u003eAXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_alk\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"14.915254237288135%\"\u003e\n \u003cp\u003eArabinoxylan\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"9.661016949152541%\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"13.05084745762712%\"\u003e\n \u003cp\u003e1N NaOH\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"16.949152542372882%\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.1864406779661%\"\u003e\n \n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"24.23728813559322%\"\u003e\n \u003cp\u003eAXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_alk_BAC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"14.915254237288135%\"\u003e\n \u003cp\u003eArabinoxylan\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"9.661016949152541%\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"13.05084745762712%\"\u003e\n \u003cp\u003e1N NaOH\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"16.949152542372882%\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.1864406779661%\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"24.23728813559322%\"\u003e\n \u003cp\u003eAXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"14.915254237288135%\"\u003e\n \u003cp\u003eArabinoxylan\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"9.661016949152541%\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"13.05084745762712%\"\u003e\n \u003cp\u003eH\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"16.949152542372882%\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.1864406779661%\"\u003e\n \n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"24.23728813559322%\"\u003e\n \u003cp\u003eAXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w_BAC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"14.915254237288135%\"\u003e\n \u003cp\u003eArabinoxylan\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"9.661016949152541%\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"13.05084745762712%\"\u003e\n \u003cp\u003eH\u003csub\u003e2\u003c/sub\u003eO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"16.949152542372882%\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.1864406779661%\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\n\u003cp\u003eFig.1 Schematic representation of preparation procedure of xylan (arabinoxylan, AXyl, and xylan, Xyl) and PVA solutions referred as Methods A and B using two types of solvent: water, and sodium hydroxide, respectively. Cationic surfactant (benzalkonium chloride, BAC) was added in the final stage\u003c/p\u003e\n\n\u003cp\u003eAnalyses applied to characterize spinning solutions\u003c/p\u003e\n\u003cp\u003eRheological properties of the solutions were measured using Anton Paar Modular Compact Rheometer MCR 302 equipped with concentric cylinder CC27 system at temperature of 20 \u0026deg;C. The pHs and conductivities of the solutions were determined with the multi parameter meter (VWR MU 6100L). The surface tension was measured by the Du Nouy Ring method using a platinum ring and surface tension tester (Kr\u0026uuml;ss GmbH, Hamburg, Germany).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eElectrospinning\u003c/p\u003e\n\u003cp\u003eElectrospinning was performed using a modular bench top Spinbox instrument (Bioinicia, Valencia, Spain). The distance between nozzle and collector plate was 13 cm, and pumping speed was 0.3 mL/h. The current applied varied from 25 to 12 kV depending on the composition (conductivity) of the electrospun solution.\u003c/p\u003e\n\u003cp\u003eSEM\u003c/p\u003e\n\u003cp\u003eHitachi SU3500 scanning electron microscope was applied to analysed gold-coated samples. Images were taken at the accelerated voltage of 10 kV using various magnifications: 1000x and 10,000x. Diameters of spun fibres were analysed using ImageJ software. At least 100 fibres were measured to determine the mean diameter and standard deviations.\u003c/p\u003e\n\u003cp\u003eFT-IR analysis\u003c/p\u003e\n\u003cp\u003eA PerkinElmer FT-IR Spectrometer Frontier equipped with ATR sampling accessory was used to acquire spectra of electrospun mats. Spectra were recorded in the range of 4000 to 400 cm\u003csup\u003e-1\u003c/sup\u003e at resolution 4 cm\u003csup\u003e-1\u003c/sup\u003e. Each spectrum consisted of 10 scanning runs.\u003c/p\u003e\n\u003cp\u003eContact angle measurements\u003c/p\u003e\n\u003cp\u003eThe contact angles of the electrospun mats were measured using a sessile drop test method. The electrospun mat was fixed on the sample glass with double-sided tape in order to obtain as smooth surface as possible. \u0026nbsp;10 \u0026micro;L of deionised water was placed on the surface of the sample by syringe and three images were immediately taken by camera and handled using CAM 2008 software (KSV instruments, Finland). Out of the three images, the software calculates the contact angles of the water drop on the surface. At least 5 different locations were measured per each mat.\u0026nbsp;\u003c/p\u003e"},{"header":"Results And Discussion","content":"\u003cp\u003eElectrospinning of Xyl\u003csub\u003e10\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w and AXyl\u003csub\u003e10\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w solutions prepared using Method A\u003c/p\u003e\n\u003cp\u003eIn Method A, hot water (80 \u0026deg;C) was used to prepare 10 wt.% xylan (Xyl and AXyl) solutions according to the procedure described by Duan et al. (2019). At 10 wt.% concentration, the beechwood xylan powder was soluble in hot water at 80 \u0026deg;C, whereas the barley husk xylan powder formed a dispersion. Indeed, xylans isolated from biomass are known to have poor solubility in aqueous and aprotic solvents (Jain et al. 2001). PVA concentration of 7 wt.% was chosen based on the preliminary electrospinning trials and easy spinnability at room temperature. Increase in PVA concentration to 10 wt.% resulted in formation of thick gel in the syringe.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIn general, no disturbances in flow coming from nozzle (so-called, Taylor cone) were observed during spinning of the solution containing beechwood xylan and PVA mixture. The SEM images of the electrospun mat containing beechwood xylan (10 wt%) and PVA (7 wt%) have been shown in Fig. 2. The\u0026nbsp;Xyl\u003csub\u003e10\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w\u0026nbsp;electrospun mat had a homogeneous physical appearance. However, SEM images (Fig. 2, left) show that nanofibers were containing inclusions such as local thickenings (knots) and beads.\u003c/p\u003e\n\u003cp\u003eFig. 2 SEM images of Xyl\u003csub\u003e10\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w fibres: magnification 1000x (left) and 10,000x (right)\u003c/p\u003e\n\u003cp\u003eIn the case of the AXyl10_PVA7_w solution prepared by Method A, separation of flow coming from the nozzle into white and dark brownish parts became evident immediately after the formation of Taylor cone. More continuous colourless part of the flow resulted in the white or slightly beige mat on the collector plate, which was interrupted by the dark brownish part as shown in Fig. 3. The brownish part flied to collector plate in the form of droplets. Some of these brownish droplets were falling under gravity force in the interspace between nozzle and collector. Several attempts were made to increase the electrostatic force, for example, by increasing voltage and by reducing distance between nozzle and collector plate to minimum. However, it was impossible to overcome the effect of the gravitational force.\u003c/p\u003e\n\u003cp\u003eFig. 3 Formation of white and brownish parts during electrospinning of AXyl\u003csub\u003e10\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w solution\u003c/p\u003e\n\u003cp\u003eThe morphology of the AXyl\u003csub\u003e10\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w mat was studied using SEM analysis and the images have been shown in Fig. 4. A typical morphology of brownish droplets is indicated with boundary line in Fig. 4 (left) showing as fibreless spot. Instead, the fibrous part of the AXyl\u003csub\u003e10\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w electrospun mat was containing inclusions, such as local fiber thickenings and large fiber joints which are visible in Fig. 4 (right).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFig. 4 SEM images of AXyl\u003csub\u003e10\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w fibres obtained as different magnifications: 1000x (left) and 10,000x (right)\u003c/p\u003e\n\u003cp\u003eElectrospinning of arabinoxylan/PVA solutions prepared using Method B\u003c/p\u003e\n\u003cp\u003eDuring electrospinning of the AXyl\u003csub\u003e10\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w solution, it was clear that phase separation in PVA-rich phase and hemicellulose-rich phase was taken place. Most probably, the insolubility of arabinoxylan extract in water was the main reason for flow instability. After a careful literature review on electrospinning of hemicelluloses, it was decided to use 1 N NaOH solution to dissolve arabinoxylan and decrease the concentration to 2.5 wt%. While the flow of AXyl\u003csub\u003e2.5\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_alk solution was improved compared to AXyl\u003csub\u003e10\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w solution, the formation of droplets caused by flow instabilities was still noticeable. The electrospun fibres have been shown in Fig. 5. The thickest fibres of the study were spun from AXyl\u003csub\u003e2.5\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_alk solution (Fig. 5, right).\u003c/p\u003e\n\u003cp\u003eFig. 5 SEM images of AXyl\u003csub\u003e2.5\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_alk fibres at magnifications: 1000x (left) and 10,000x (right)\u003c/p\u003e\n\u003cp\u003eIn order to improve flow, the further decrease of arabinoxylan content and addition of the cationic surfactant were implemented. SEM images of the electrospun fibres have been shown in Fig. 6. As expected, both decrease in the arabinoxylan concentration and the addition of the cationic surfactant, benzalkonium chloride, resulted in improvement of the flow of the solution used in electrospinning and, simultaneously, the quality of the electrospun mat. Moreover, comparison of mats in Fig. 5 (left) and Fig. 6 (left) and Fig. 7 (left) and results shown in Table 2 revealed that the electrospun mat containing cationic surfactant was composed by the thinner fibres and had the denser structure compared to the others. None of the applied strategies, however, led to the complete disappearance of defects such as beads and local fiber thickenings. Nevertheless, the large fiber joints were not found in mats consisting of AXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_alk and AXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_alk_BAC.\u003c/p\u003e\n\u003cp\u003eFig. 6 SEM images of AXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_alk fibres at magnifications: 1000x (left) and 10,000x (right)\u003c/p\u003e\n\u003cp\u003eFig. 7 SEM images of AXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_alk_BAC fibres at magnifications: 1000x (left) and 10,000x (right)\u003c/p\u003e\n\u003cp\u003eElectrospinning of AXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e solutions prepared by Method A with and without surfactant\u003c/p\u003e\n\u003cp\u003eThere was also an interest to see if by applying similar strategy, i.e., decrease in hemicellulose concentration (i.e., from originally used 10 wt.% to 1 wt.%) and addition of cationic surfactant will lead to improvements in the case of water-based solution of arabinoxylan. Analysis of SEM images of AXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w and AXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w_BAC mats shown in Fig. 8 and Fig. 9 revealed trends similar to ones found for alkali-dissolved xylan with PVA (AXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_alk) and with cationic surfactant (AXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_alk_BAC) containing mats. The electrospun mats were more uniform compared to the initial AXyl\u003csub\u003e10\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w mat and fibres were finer. Somehow, the exchange of alkali to water led to the denser structure of the resulting mat.\u003c/p\u003e\n\u003cp\u003eFig. 8 SEM images of electrospun AXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w mats without cationic surfactant: 1000x (left) and 10,000x (right)\u003c/p\u003e\n\u003cp\u003eFig. 9 SEM images of electrospun AXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w mats with cationic surfactant: 1000x (left) and 10,000x (right)\u003c/p\u003e\n\u003cp\u003eSize of electrospun fibres\u003c/p\u003e\n\u003cp\u003eAverage diameters of the fibres in the structure of the electrospun mats were calculated using Image J software and the results have been presented in Table 2. Results shown in the Table 2 are average of calculations made for 100 fibres per each type of mat. The 7% aqueous solution of PVA spun at pumping rate of 0.3 mL/h, distance of 13 cm, voltage of 20 kV was used as a reference. From Table 2 it is evident that solution containing xylan extracted from beechwood, Xyl\u003csub\u003e10\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w, resulted in finer fibers than solution containing arabinoxylan extracted from barley husks, AXyl\u003csub\u003e10\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w. Operating conditions during spinning were identical for both types of xylan. Similarity between fibre size of PVA\u003csub\u003e7\u003c/sub\u003e_w and AXyl\u003csub\u003e10\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w mats and flow (phase) separation observed in the case of the AXyl\u003csub\u003e10\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w solution electrospinning can indicate that the fiber mat consisted mostly of PVA while arabinoxylan was disposed as droplets. Chemical composition of the two phases and the results of the FTIR analysis of the mats will be discussed in the following section. Generally, the mats spun from the aqueous solutions had thinner fibres than their analogues spun from the alkaline solutions. Moreover, both the decrease in concentration of arabinoxylan from 2.5 to 1.0 wt.% and use of cationic surfactant resulted in thinner fibers. More specifically, the 42% decline in the fiber diameter was calculated after addition of cationic surfactant to AXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w solution.\u003c/p\u003e\n\u003cp\u003eTable 2 Calculated diameters and defects of fibres\u003c/p\u003e\n\u003ctable border=\"1\" cellpadding=\"0\" cellspacing=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003eSample\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003eDiameter of fibres (nm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003eSize of defects (nm)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003ePVA\u003csub\u003e7\u003c/sub\u003e_w\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e148.0 \u0026plusmn; 39.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e\u0026gt; 300\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003eXyl\u003csub\u003e10\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e100.5 \u0026plusmn; 39.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e\u0026lt; 300\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003eAXyl\u003csub\u003e10\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e146.8 \u0026plusmn; 53.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e\u0026gt; 300\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003eAXyl\u003csub\u003e2.5\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_alk\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e212.3 \u0026plusmn; 55.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e\u0026gt; 300\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003eAXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_alk\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e156.3 \u0026plusmn; 43.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e\u0026gt; 300\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003eAXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_alk_BAC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e121.2 \u0026plusmn; 36.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e\u0026gt; 200\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003eAXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e130.5 \u0026plusmn; 35.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e\u0026lt; 250\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003eAXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w_BAC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e75.7 \u0026plusmn; 29.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e\u0026gt; 200\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eCharacterisation of electrospinning solutions\u003c/p\u003e\n\u003cp\u003eThe appearance of the fibres collected depended on many factors (Jarusuwannapoom et al. 2005). One of them is the viscoelastic force, which depends on the concentration of the solution, average molecular weight of the polymer, viscosity, and surface tension of the solution. Another on is the gravitational force which depends on the density and the conductivity of the solution and electrostatic forces. Recognising this, conductivity, viscosity, and surface tension of solutions were measured, and results have been shown in Table 3.\u0026nbsp;The solution conductivity is known to be one of the main parameters in the electrospinning process since the viscous polymer solution is stretched due to repulsion of the charges present on its surface.\u0026nbsp;As expected, presence of sodium hydroxide drastically increased the conductivity of the solutions. Increased conductivity resulted in decrease of voltage at which Taylor cone is formed (e.g., voltage decreased from 25 to 20 kV for the AXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w and AXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_alk solution, respectively). However, high conductivity is not always guarantee spinnability of the solution. For example, solution of AXyl\u003csub\u003e10\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w had higher conductivity than AXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w solution but its spinnability was problematic due to extremely high viscosity. Viscosity curves of the solutions as a function of shear stress including 10 and 1 wt.% AXyl_w, 2.5 and 1 wt.% AXyl_alk and 7 wt.% PVA, are shown in Fig. 10.\u003c/p\u003e\n\u003cp\u003eTable 3 pH, conductivity, shear viscosity and surface tension of the xylan_PVA solutions\u003c/p\u003e\n\u003ctable border=\"1\" cellpadding=\"0\" cellspacing=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"24.697754749568222%\"\u003e\n \u003cp\u003eSample\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.825561312607945%\"\u003e\n \u003cp\u003epH\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.825561312607945%\"\u003e\n \u003cp\u003eConductivity (mS/cm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.825561312607945%\"\u003e\n \u003cp\u003eShear viscosity\u003csup\u003e1\u003c/sup\u003e (Pa\u0026middot;s)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.825561312607945%\"\u003e\n \u003cp\u003eSurface tension, \u0026gamma; (mN/m)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"24.697754749568222%\"\u003e\n \u003cp\u003eXyl\u003csub\u003e10\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.825561312607945%\"\u003e\n \u003cp\u003e7.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.825561312607945%\"\u003e\n \u003cp\u003e2.53\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.825561312607945%\"\u003e\n \u003cp\u003e2.03\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.825561312607945%\"\u003e\n \u003cp\u003e\u0026gt; 80\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"24.697754749568222%\"\u003e\n \u003cp\u003eAXyl\u003csub\u003e10\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.825561312607945%\"\u003e\n \u003cp\u003e8.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.825561312607945%\"\u003e\n \u003cp\u003e1.29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.825561312607945%\"\u003e\n \u003cp\u003e11.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.825561312607945%\"\u003e\n \u003cp\u003e55.3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"24.697754749568222%\"\u003e\n \u003cp\u003eAXyl\u003csub\u003e2.5\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_alk\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.825561312607945%\"\u003e\n \u003cp\u003e13.3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.825561312607945%\"\u003e\n \u003cp\u003e54.10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.825561312607945%\"\u003e\n \u003cp\u003e0.55\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.825561312607945%\"\u003e\n \u003cp\u003e42.8\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"24.697754749568222%\"\u003e\n \u003cp\u003eAXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_alk\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.825561312607945%\"\u003e\n \u003cp\u003e13.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.825561312607945%\"\u003e\n \u003cp\u003e57.37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.825561312607945%\"\u003e\n \u003cp\u003e0.25\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.825561312607945%\"\u003e\n \u003cp\u003e41.9\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"24.697754749568222%\"\u003e\n \u003cp\u003eAXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_alk_BAC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.825561312607945%\"\u003e\n \u003cp\u003e13.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.825561312607945%\"\u003e\n \u003cp\u003e57.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.825561312607945%\"\u003e\n \u003cp\u003e0.31\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.825561312607945%\"\u003e\n \u003cp\u003e37.5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"24.697754749568222%\"\u003e\n \u003cp\u003eAXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.825561312607945%\"\u003e\n \u003cp\u003e7.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.825561312607945%\"\u003e\n \u003cp\u003e0.63\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.825561312607945%\"\u003e\n \u003cp\u003e0.12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.825561312607945%\"\u003e\n \u003cp\u003e49.0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"24.697754749568222%\"\u003e\n \u003cp\u003eAXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w_BAC\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.825561312607945%\"\u003e\n \u003cp\u003e6.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.825561312607945%\"\u003e\n \u003cp\u003e1.17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.825561312607945%\"\u003e\n \u003cp\u003e0.11\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.825561312607945%\"\u003e\n \u003cp\u003e37.0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003csup\u003eshear viscosity was determined at shear rate of 50 1/s\u003c/sup\u003e\u003c/p\u003e\n\u003cp\u003eBoth xylans used, beech (Xyl) and barley husk (AXyl), contains of 4-O-methyl-glucuronic acids (K\u0026ouml;hnke et al. 2009, Teleman et al. 2002), and, thus, they are negatively charged in aqueous solutions. Dissolution of the negatively charged groups is highly dependent on pH (Sj\u0026ouml;str\u0026ouml;m 1989). In the solutions studied (Table 3), these uronic acid groups are known to be fully dissociated at pH 6-8.5. At higher pH values when pH exceeds 12, also carbonyls and phenolic hydroxyl groups have been fully dissociated. According to manufacturer, arabinoxylan of barley husk contains lignin (Klason lignin 19.6%) bound to xylan, thus, it contains these phenolic hydroxyl groups. At pH 13, only small amount of hydroxyl groups in alcohols have reported to be dissociated (Sj\u0026ouml;str\u0026ouml;m 1989). Comparison of conductivity of AXyl\u003csub\u003e10\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w and Xyl\u003csub\u003e10\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w solutions shown in Table 3 indicates that Xyl contains higher charge (higher amount of 4-O-methyl glucuronic acid) compared to AXyl. In Table 3, increase of the pH up to 13 shows clearly that conductivity increase drastically showing increase of Na\u003csup\u003e+\u0026nbsp;\u003c/sup\u003ean OH\u003csup\u003e-\u003c/sup\u003e ions and possible increase of the dissociating groups.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eWhen cationic surfactant, i.e. benzalkonium chloride, is added, complexation of charges between xylan and surfactant is evident. The driving force for the complexation between oppositely charged polyelectrolytes and surfactants are electrostatic and hydrophobic forces (Holmberg et al. 2002). The head groups of the surfactant molecules are attracted by the charged polymer segments, and also the hydrophobic surfactant tails can interact with the hydrophobic backbone of the polyelectrolytes, such as lignin attached to xylan in AXyl. According to Table 3, surface tension of the solutions decreases from 41.9 to 37.5 (pH 13) and 49.0 to 37.0 (pH 6.5), respectively. Concentration of 10 mM for cationic surfactant (BAC) was used in the solutions, which is higher than the critical micelle concentration (CMC) of BAC reported, 3 mM (Turku and Sainio 2009). Schematic plot of the concentration dependence of the surface tension for mixed polymer solution described by Holmberg et al. (2002) shows that in the concentration of benzalkonium chloride used in the studies, CMC and critical association concentration CAC have been reach and micelles of surfactant have been formed, seen as lowered surface tension values of the solutions. Maximum effectiveness of benzalkonium chloride have been reported to exist between pH 4-10 (Handbook of Pharmaceutical Excipients 2006), indicating that the at pH 13 the quaternary ammonium compounds are not fully dissociated. Because PVA is also present in the solutions, the behavior of surfactant-polymer aggregations becomes more complex, which needs to be studied further.\u003c/p\u003e\n\u003cp\u003eFig. 10 Viscosity as a function of shear rate curves\u003c/p\u003e\n\u003cp\u003eAs shown in Fig. 10, most of the solutions tested demonstrated a shear-thinning behaviour indicating that the viscosity decreases with applied shear. Among all studied solutions, 7 wt.% PVA showed behaviour close to Newtonian in wide range of shear stresses. As was discussed earlier, 7 wt.% PVA solution was easily spinnable at ambient temperature. Thus, electrospinning solutions having viscosities close to viscosity of pure PVA 0.08 Pa\u0026middot;s (e.g, AXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w and AXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_alk with and without surfactant) had good spinnability. It was not shown here, but rheological measurements for AXyl\u003csub\u003e10\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w and AXyl\u003csub\u003e2.5\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_alk solutions made at higher temperatures (i.e., 50 and 80 \u0026deg;C) resulted in significant reduction of their viscosities. Reduction of solution viscosity is considered as an efficient way to improve its spinnability.\u003c/p\u003e\n\u003cp\u003eXyl\u003csub\u003e10\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w solution had lower viscosity than AXyl\u003csub\u003e10\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w solution (Table 3 and Fig.10). Since equal amount of PVA was used in both cases, the difference was connected to the nature of xylan. Both chemical composition and molecular mass of xylan can be a reason for that. Molar mass of xylan extracted from beechwood is lower than molar mass of arabinoxylan extracted from barley husk. Chemical compositions of xylan and arabinoxylan extracts will be discussed later.\u003c/p\u003e\n\u003cp\u003eMixing of PVA with AXyl resulted in an increased viscosity. This effect was independent on the concentration or alkalinity of the AXyl solution. Increase in the viscosity of two-component mixture may signify the polymer\u0026rsquo;s interactions (or formation of larger particulates). Lignin is supposed to be closely bound (in non-dissociated complex) to arabinoxylan in aqueous dispersion of barley husk extract. Indeed, a single step extraction, which commonly has been used to isolate xylan from barley husks (Glasser et al. 2000) resulted in xylan entrapped with lignin. Three types of linkages are known to exist between lignin and polysaccharides in lignin-carbohydrate complexes (LCC), i.e., benzyl ester-, benzyl ether- and glycosidic linkage (Lai 1991). Addition of PVA to arabinoxylan-lignin complex caused formation of hydrogen bonds between hydroxyl groups of PVA and arabinoxylan-lignin molecules, and as a consequence, increased the viscosity. At neutral pH (7.0), phenolic hydroxyl groups of lignin are not fully dissociated and thus cannot participate into formation of bonds between PVA and arabinoxylan-lignin complex. This could be one explanation why viscosity of AXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w solution is lower than viscosity of AXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_alk solution (0.12 v\u0026rsquo;s 0.25 Pa\u0026middot;s).\u003c/p\u003e\n\u003cp\u003eIncrease in viscosity was found also in the case of addition of surfactant to alkaline AXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e solution. A strong polymer-surfactant interaction could alter the rheological properties of the polymer solution, e.g., if the polymer can associate with the surfactants (Lin et al. 2004). In alkaline AXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e solution, an addition of cationic surfactant is assumed helping to form large associates between positively charged micelles of surfactant and negatively charged groups of arabinoxylan and lignin. It was very interesting to note a difference in effects caused by surfactant on viscosities of AXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w and AXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_alk solutions. Viscosity of AXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w_BAC solution was lower compared to the AXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w solution, in contrast to AXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_alk_BAC solution. The difference can be explained by the difference in the dissolution state and by the charge of the arabinoxylan in pH-neutral and alkaline solutions. Most probably, at neutral pH there was not enough anionic groups in arabinoxylan/lignin-PVA complex available to participate into electrostatic interactions with benzalkonium cations associated in micelles. Formation of free micelles non-bound electrostatically to the polymer backbone, can be responsible for decrease in viscosity in the case of AXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w_BAC solution. However, this question requires more detailed study.\u003c/p\u003e\n\u003cp\u003eSurface tension of the solution is the factor, which can affect the spinnability. According to the Taylor equation, there is a relationship between voltage applied and the surface tension of the solution:\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cimg src=\"https://myfiles.space/user_files/69515_16346c490bab499e/69515_custom_files/img1641819653.png\"\u003e\u003c/p\u003e\n\u003cp\u003ewhere V\u003csub\u003ec\u0026nbsp;\u003c/sub\u003eis the critical electrical voltage, H is the separation between the tip of nozzle (capillary) and collector plate, L is the length of the capillary, R is the radius of the capillary and \u0026gamma; is the surface tension of the solution (Yao et al. 2003). Voltage required to obtain a stable Taylor cone in a solution with or without cationic surfactant at the same working distance and pumping feed rate was noticeable different. Addition of cationic surfactant reduced clearly the surface tension of AXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_alk and AXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w on 10.5 and 24.5% (Table 3), respectively, and, as consequence, resulted in lower applied voltage.\u003c/p\u003e\n\u003cp\u003eThere is a strong connection between polymer concentration and thickness of fibres. As was discussed earlier, the average thickness of AXyl\u003csub\u003e2.5\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_alk fibres was higher than thickness of AXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_alk fibres (212.3 \u0026plusmn; 55.7 v\u0026rsquo;s 156.3 \u0026plusmn; 43.0 nm) (Table 2). The decrease in thickness of fibres with the decrease of polymer concentration was previously described by researchers using polystyrene (Uyar and Besenbacher 2008; Lee et al. 2003). Most often, high polymer concentration means higher viscosity. According to the studies on polystyrene, the high polymer concentrations is prerequisite for formation of stable jet during electrospinning. Stable jet should reduce the number of beads (defects) significantly. As stated earlier, the spinnability of AXyl_PVA\u003csub\u003e7\u003c/sub\u003e system with increase of arabinoxylan concentration was impossible due to too high viscosity of the solution. Based on the results of this work, it is preferred to increase the concentration of polymers and use of higher temperatures to improve the spinnability of solution and to obtain defect-free fibres.\u003c/p\u003e\n\u003cp\u003eChemical composition of nanofibrous mats\u003c/p\u003e\n\u003cp\u003eThe FT-IR spectroscopy was used to assess the chemical composition of the electrospun mats, and the spectra have been presented in Fig. 11. In order to interpret the FT-IR spectra of the electrospun mats, the spectra of pure powders of PVA, arabinoxylan extracted from barley husk and xylan extracted from beechwood were measured and peak assignments have been shown in Table 4.\u003c/p\u003e\n\u003cp\u003eTable 4 The main bands identified on FT-IR spectra of Xyl, AXyl and PVA powders\u003c/p\u003e\n\u003ctable border=\"1\" cellpadding=\"0\" cellspacing=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003eWavenumbers for Xyl\u003c/p\u003e\n \u003cp\u003e(cm\u003csup\u003e-1\u003c/sup\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003eWavenumbers for AXyl\u003c/p\u003e\n \u003cp\u003e(cm\u003csup\u003e-1\u003c/sup\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003eWavenumbers for PVA\u003c/p\u003e\n \u003cp\u003e(cm\u003csup\u003e-1\u003c/sup\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e987\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e987\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e916\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e1041\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e1035\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e1086\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e1160\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e1160\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e1142\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e1250\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e1252\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e1238\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e1377\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e1377\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e1378\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e1408\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e1414\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e1418\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e1510\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e1603\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e1595\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e1650\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e2919\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e2919\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e2940\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e3343\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e3341\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e3272\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eFollowing conclusions were drawn based on data shown in Table 4. First, the main difference between spectra of xylan and arabinoxylan is absence of peaks at 1510 and 1595 cm\u003csup\u003e-1\u003c/sup\u003e which can be assigned to the aromatic skeletal vibrations of lignin residue (Sun et al. 2005). Second, the common features for xylan and arabinoxylan are peaks associated with xylopyranose backbone: peak at 1035 \u0026ndash; 1041 cm\u003csup\u003e-1\u003c/sup\u003e, which is attributed to the C \u0026ndash; O stretching, peaks at 2919 cm\u003csup\u003e-1\u003c/sup\u003e and 3341 \u0026ndash; 3343 cm\u003csup\u003e-1\u003c/sup\u003e assigned to C \u0026ndash; H and O \u0026ndash; H stretching, respectively (Duan et al. 2019). The peak at 1035 \u0026ndash; 1041 cm\u003csup\u003e-1\u0026nbsp;\u003c/sup\u003ein xylans has two shoulders at 1160 and 987 cm\u003csup\u003e-1\u003c/sup\u003e of low-intensity. The peak at 1603 cm\u003csup\u003e-1\u003c/sup\u003e in xylan spectra can be explained by absorbed water. In general, the spectra of xylans and PVA are close to each other, for example the peaks 1377 \u0026ndash; 1378, 1414 \u0026ndash; 1418 and 1252 - 1238 cm\u003csup\u003e-1\u003c/sup\u003e corresponding to the C \u0026ndash; H and C \u0026ndash; O stretching and bending vibrations in xylans and PVA molecules (Sun et al. 2005, Bary et al. 2019). The characteristic peak of PVA at 1086 cm\u003csup\u003e-1\u003c/sup\u003e has shoulder at 1142 cm\u003csup\u003e-1\u003c/sup\u003e, which determines polymer crystallinity (Mallapragada et al. 1996, Tretinnikov et al. 2012). There are differences between the xylan and PVA peaks obtained in region above 2000 cm\u003csup\u003e-1\u003c/sup\u003e. The peaks at 3272 and 2940 cm\u003csup\u003e-1\u003c/sup\u003e correspond to O \u0026ndash; H and C \u0026ndash; H stretching of PVA, respectively.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFig. 11 FT-IR spectra of studied electrospun mats and reference components: PVA, xylan and arabinoxylan powders.\u003c/p\u003e\n\u003cp\u003eAnalysis of spectra of AXyl\u003csub\u003e10\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w droplets and fibres showed that fibres had more pronounced peak at 1083 cm\u003csup\u003e-1\u003c/sup\u003e that is closer to the characteristic peak of PVA, while droplets had more pronounced peak at 1039 cm\u003csup\u003e-1\u003c/sup\u003e and no peak at 1083 cm\u003csup\u003e-1\u003c/sup\u003e. Use of alkaline for arabinoxylan dissolution caused the formation of the peaks at 1434 and 1565-1574 cm\u003csup\u003e-1\u003c/sup\u003e. They are considered as shifts from peaks with original positions 1421 and 1595 cm\u003csup\u003e-1\u003c/sup\u003e which corresponds to aromatic skeletal vibrations. \u0026nbsp;It is known that in an alkaline solution, ionization of the phenolic hydroxyl groups is responsible for the shifts of the phenolic absorption bands of compounds (Morohoshi 1991). The arabinoxylan extract from barley husks contained 19.6 % of Klason lignin. Lignin was thought to be a reason why AXyl formed the dispersion in water. Addition of surfactant to the AXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w and AXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_alk solutions was appeared as a sharp peak at 2855 cm\u003csup\u003e-1\u003c/sup\u003e, which is typical for benzalkonium chloride.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eHydrophilicity of electrospun mats\u003c/p\u003e\n\u003cp\u003eContact angles of the electrospun mats as a function of composition has been shown in Table 5, where the mean values and standard deviations have been calculated out of 15 (3x5) measurements. Two-sample t-test and Tukey\u0026rsquo;s simultaneous test were applied to determine if changes in contact angle from the PVA\u003csub\u003e7\u003c/sub\u003e_w was statistically significant at P-value less than 0.05.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTable 5 Contact angles of electrospun mats\u003c/p\u003e\n\u003ctable border=\"1\" cellpadding=\"0\" cellspacing=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003eSample\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003eContact angle (\u0026deg;)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003eTrend\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003ePVA\u003csub\u003e7\u003c/sub\u003e_w\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e46.9 \u0026plusmn; 8.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003eReference\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003eXyl\u003csub\u003e10\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e30.2 \u0026plusmn; 5.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e\u0026darr; (S)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003eAXyl\u003csub\u003e10\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e54.3 \u0026plusmn; 6.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e\u0026uarr; (NS)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003eAXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e48.1 \u0026plusmn; 2.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e\u0026uarr; (NS)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003eAXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_alk\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e18.0 \u0026plusmn; 3.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"33.333333333333336%\"\u003e\n \u003cp\u003e\u0026darr; (S)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003csup\u003eS corresponds to significant change (at probability level 0.05), NS corresponds to non-significant change (at probability level 0.05), and arrows show the trends (\u0026uarr; corresponds to improvements and \u0026darr; corresponds to decline).\u003c/sup\u003e\u003c/p\u003e\n\u003cp\u003eThe contact angle measurements are very sensitive to roughness and porosity of surface. The difference in microstructure of spun mats can be assessed from SEM images presented in earlier section. As can be seen, equal times (means equal fused volumes) of spinning was not warranty that fibre mats produced had similar microstructure (i.e., porosity). As can be seen from Table 5, the contact angle of Xyl\u003csub\u003e10\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w mat was significantly lower than the contact angle of PVA\u003csub\u003e7\u003c/sub\u003e_w and AXyl\u003csub\u003e10\u003c/sub\u003e_PVA7_w mats. Hydrophilic nature of former mat can be explained by hydrophilicity of beechwood xylan. Presence of lignin in extract of arabinoxylan can explain its higher hydrophobicity. Decrease in content of arabinoxylan extract (from 10 to 1 wt%) and consequently in lignin concentration led to predictable decrease in hydrophobicity of mat. Usage of alkaline for arabinoxylan dissolution led to formation of highly hydrophilic mats. This hydrophilicity is in a good agreement with results of FTIR analysis which revealed ionization of the phenolic hydroxyl groups of lignin at alkaline conditions.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThis study was focused on the spinnability of arabinoxylan extracted from barley husk. Two different solvents were applied to produce the spinning solutions. It was found that alkaline conditions were required for solubilization of the arabinoxylan extract. Among other components of arabinoxylan extract, lignin is believed to be a major one to determine solubility of this extract. In contrast to arabinoxylan extract, the extract of xylan obtained from beechwood was easily soluble in hot water. \u0026nbsp;Lower viscosity and improved spinnability of Xyl\u003csub\u003e10\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w compared to AXyl\u003csub\u003e10\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w solution was explained by presence of lignin in arabinoxylan. In addition, lignin is found to be responsible for increased hydrophobicity of AXyl\u003csub\u003e10\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w nanofibrous mats.\u003c/p\u003e\n\u003cp\u003eIn future studies, usage of the lignin-rich solution to improve water resistance of the PVA-based nanofibrous mats can be used. However, as can be seen in the cases of AXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_w and AXyl\u003csub\u003e1\u003c/sub\u003e_PVA\u003csub\u003e7\u003c/sub\u003e_alk mats, the solvent nature could also drastically change hydrophilicity of mats obtained. From rheological measurements, it became clear that type of solvent was a limiting factor affecting the interaction between polymers (i.e., PVA and arabinoxylan/lignin) and surfactants. However, more work is needed to understand the interactions between molecules and molecular structure of the nanofibrous mats. The materials electrospun in this study as composed of 75-200 nm fibres have potential application in the fields, where high aspect ratio (or high surface area) of fibres is required (e.g., air filtration). However, their performance should be further studied.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eAcknowledgements\u003c/p\u003e\n\u003cp\u003eThis study was supported by the Business Finland funded BioProt Co-creation project (1.7.2020-28.2.2021), which aimed on development of bio-based and biodegradable nonwoven materials from forest industry and use as protective equipment. Authors are thankful to Prof. Kristiina Oksman and Dr. Linn Berglund from the Laboratory of Wood and Bionanocomposites, Lule\u0026aring;, Sweden for supply of arabinoxylan extract.\u003c/p\u003e\n\u003cp\u003eFunding\u003c/p\u003e\n\u003cp\u003eThis study was mainly supported by the Business Finland funded BioProt Co-creation project (1.7.2020-28.2.2021), which aimed on development of bio-based and biodegradable nonwoven materials from forest industry and use as protective equipment. Additional funding was obtained as a grant awarded by Etel\u0026auml;-Karjalan S\u0026auml;\u0026auml;st\u0026ouml;pankkis\u0026auml;\u0026auml;ti\u0026ouml; to Dr. Katri Laatikainen.\u003c/p\u003e\n\u003cp\u003eConflict of interest\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.\u003c/p\u003e\n\u003cp\u003eData availability\u003c/p\u003e\n\u003cp\u003eThe corresponding author will provide the datasets generated for this study on request.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAuthors\u0026rsquo; contributions\u003c/p\u003e\n\u003cp\u003eSB designed, performed most of experiments, analyzed the data, and wrote the manuscript; KK characterized properties of solutions, and wrote the manuscript; SH revised the manuscript; KL obtained the funding and revised the manuscript.\u003c/p\u003e\n\u003cp\u003eEthics approval\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e"},{"header":"References","content":"\u003cp\u003eAbdullah@Shukry NA, Sekak KA, Ahmad MR and Bustami Effendi TJ (2014) Characteristics of electrospun PVA-Aloe vera nanofibres produced via electrospinning. 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Chem Mater 15:1860-1864. https://doi.org/10.1021/cm0210795\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":true,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"cellulose","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"cels","sideBox":"Learn more about [Cellulose](https://www.springer.com/journal/10570)","snPcode":"10570","submissionUrl":"https://submission.nature.com/new-submission/10570/3","title":"Cellulose","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Arabinoxylan, electrospinning, nanofibers, rheology, FTIR spectroscopy, contact angle","lastPublishedDoi":"10.21203/rs.3.rs-1210254/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-1210254/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eValorisation of bio-based materials derived from agricultural and industrial side-streams or waste-streams is a basis of circular economy. However, the success of it depends on the full understanding of materials and finding their optimal way of processing. Barley husk is a side-stream waste material derived from the starch and ethanol production. This study is focused on the processability of the arabinoxylan extracted from barley husk using the electrospinning technique to produce thin xylan-poly(vinyl alcohol) fibers. As a comparison, lignin-free xylan of beech wood was used. The properties of spinning solutions and resulting nanofibrous mats were assessed by using rheological measurements, FTIR spectroscopy, scanning electron microscopy and contact angle measurements. It was found that solubility plays a crucial role in the spinnability of xylan extracts. Decrease in viscosity of arabinoxylan achieved by decreasing its concentration was found to improve the jet stability but at the same time, to reduce the diameter of spun fibre. Hydrophilicity of nanofibrous mats were strongly affected by the type of xylan and solvent used.\u003c/p\u003e","manuscriptTitle":"Study on Spinnability of Arabinoxylan Extracted From Barley Husks","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2022-01-10 15:43:57","doi":"10.21203/rs.3.rs-1210254/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Major revisions","date":"2022-02-22T12:18:49+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2022-01-09T15:56:37+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2022-01-07T01:55:49+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"Cellulose","date":"2022-01-02T04:17:48+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2021-12-29T11:26:34+00:00","index":"","fulltext":""},{"type":"submitted","content":"Cellulose","date":"2021-12-28T04:39:37+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"cellulose","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"cels","sideBox":"Learn more about [Cellulose](https://www.springer.com/journal/10570)","snPcode":"10570","submissionUrl":"https://submission.nature.com/new-submission/10570/3","title":"Cellulose","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"530699b8-1c88-4b47-a078-338bd9a1d222","owner":[],"postedDate":"January 10th, 2022","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[{"id":9633844,"name":"Cellular Metabolism"},{"id":9633845,"name":"Cellular \u0026 Molecular Neuroscience"}],"tags":[],"updatedAt":"2022-07-14T08:00:32+00:00","versionOfRecord":[],"versionCreatedAt":"2022-01-10 15:43:57","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-1210254","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-1210254","identity":"rs-1210254","version":["v1"]},"buildId":"_2-kVJe1T_tPrBINL-cwx","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}