Thermoplastic starch/bentonite clay nanocomposite reinforced with vitamin B2: Physicochemical characteristics and release behavior

Thermoplastic starch/bentonite clay nanocomposite reinforced with vitamin B2: Physicochemical characteristics and release behavior | 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 Thermoplastic starch/bentonite clay nanocomposite reinforced with vitamin B 2 : Physicochemical characteristics and release behavior Abolfazl Heydari, Milad KhajeHassani, Haniyeh Daneshafruz, Sepideh Hamedi, and 6 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-2587534/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Thermoplastic starch (TPS) attracted great interest in the biopolymer industry due to its obvious advantages, such as biodegradability and renewable resources, as substitutes for petroleum-based materials. This study is focused on designing TPS/bentonite clay (BC) nanocomposite (TPS/BC) reinforced with vitamin B 2 (VB). The TPS nanocomposites loaded with various contents of BC were prepared using regular cornstarch/clay plasticized with glycerol. Subsequently, the various content of VB was encapsulated into TPS/BC. The effects of VB were investigated on the physicochemical properties of the TPS/BC films including mechanical and thermal properties, water uptake, and weight loss in water. The tensile strength and Young’s modulus of TPS/BC/VB films were found to increase significantly with adding and rising the VB content. The highest tensile and Young’s modulus values were observed for the nanocomposites containing 5 php of VB and 3 php of BC which indicates their synergistic effects on the mechanical properties of TPS. TPS reinforced with 1 php and 5 php VB showed an increase in water uptake compared to the TPS. The release of VB was evaluated from the nanocomposite films. Our findings show that higher BC content leads to lower VB release, which indicates the control of VB release by BC content. Thermoplastic starch Vitamin B2 Active packaging Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 1. Introduction Starch, as one of the most promising candidates in the biopolymer industry, has been widely considered, since it is completely biodegradable, available from renewable resources, abundant in nature, and cost-effective. However, high brittleness is one of the disadvantages, which is seen in native starch as a plastic material. Therefore, by adding a suitable plasticizer, it can be converted to thermoplastic starch (TPS) under special thermal and shear conditions [ 1 – 3 ]. This plastification process leads to the destruction of crystallinity and increase in chain flexibility [ 4 ]. However, the main shortcoming of TPS is the recrystallization phenomena caused by its hydrophilic character, as it leads to unsatisfactory mechanical properties during storage [ 1 ]. The incorporation of filler in the polymer matrix can be considered as one of the most practical strategies to improve the mechanical properties of starch-based films, as well as one of the important approaches to develop barrier properties to prevent the penetration of moisture and oxygen [ 5 – 7 ]. Layered silicates have proven to be effective reinforcing agents to improve barrier and mechanical properties of the polymer matrix. The addition of a definite amount of inorganic silicate layers not only provides a barrier for oxygen and water molecules but also, increases strength and modulus strength [ 8 ]. The layered silicates used in nanocomposites include montmorillonite, bentonite, hectorite, saponite, and other modified cationic compounds. Bentonite is one of the most commonly used clays due to its low cost, availability in large quantities, and its environmentally benign nature [ 9 – 11 ]. Nanocomposite films incorporating bioactive molecules such as antimicrobials, antioxidants, and vitamins received great attention in the cosmetic, pharmaceutical, nutraceutical, and food industries [ 12 ]. Among them, vitamins are organic substances that are classified into fat-soluble (vitamin A, vitamin D, vitamin E, vitamin K, and vitamin B 2 ) and water-soluble (vitamin C and the B-complex vitamins such as vitamin B 6 , vitamin B 12 , and folate) ones [ 13 ]. Vitamin B 2 , also known as riboflavin, is one of the essential water-soluble vitamins for humans [ 14 ]. Vitamin B 2 plays an important role in the metabolism of carbohydrates, lipids, and proteins and is crucial for the generation of biological energy in the electron-transport system. Vitamin B 2 is an abundant, naturally occurring chemical existing in various food like milk, dairy products, fish, meats, fruit, and vegetables [ 15 ]. This vitamin is also essential for living organisms and plays a vital role in the production and regulation of certain hormones, and the formation of red blood cells [ 16 ]. Vitamin B 2 is known as a photosensitizer, which can produce reactive oxygen species (ROS) at a certain wavelength leading to the deactivation of malignant cells and pathogenic microorganisms [ 17 ]. Sufficient dietary or supplemental intake of vitamin B 2 has been reported to provide anti-oxidant, anti-aging, anti-inflammatory, and anti-cancer properties [ 18 ]. Hair loss, skin crack, depression, blurred vision, swollen mouth, and tongue are the most famous symptoms of vitamin B 2 deficiency [ 19 ]. The human body is unable to synthesize vitamin B 2 and it should be supplied in dietary [ 20 ]. Vitamins are sensitive to light, heat and oxidations and so they should be preserved from these destructive agents. In this context, encapsulation of vitamin B 2 in the polymer matrix has emerged as a promising strategy to overcome the above obstacles [ 13 ]. Vitamins are encapsulated via different methods, including a layer-by-layer technique, electrospinning/electrospraying, freeze-drying, coprecipitation, solvent casting, spray drying, and complex coacervation [ 21 – 23 ]. Lee et al. prepared hyaluronic acid hydrogels via visible light-induced thiol-ene reaction in the presence of crosslinked riboflavin. Delayed gelation is promising for in situ medical applications, such as ophthalmology and stomatology [ 24 ]. Microencapsulation of vitamin B 2 was conducted in alginate hydrogel coated with chitosan. Results demonstrated the encapsulation efficiency depending on concentration of both polymers [ 25 ]. Chitosan-based printed materials were synthesized for efficient delivery of vitamin B 2 [ 26 ]. The initial burst followed by slow drug release was concluded in the case of VB encapsulated into hydrophobic epichlorohydrin-crosslinked β-cyclodextrin nanofibers [ 22 ]. The release of uncoated riboflavin and ethyl cellulose-coated barium alginate beads in the media with different pH values was studied by Bajpai and Sharma. The slower drug release was observed for the coated beads [ 27 ]. Vitamin B 2 was also loaded into starch/polyacrylic acid based interpenetrating network. This delivery system was suggested for colon-targeted drug-delivery [ 28 ]. The colored silk fabric, bearing frame retardant and antibacterial properties, was prepared by layer-by-layer electrostatic self-assembly of chitosan and VB on silk fabric [ 29 ]. The layered encapsulation of vitamin B 2 and β-carotene was studied in alginate multilayered gel microspheres for their simultaneous delivery to the intestinal tract [ 27 , 30 ]. Vitamin B 2 and vitamin B 3 were encapsulated into chitosan, modified chitosan, gum arabic, maltodextrin, sodium alginate, and pectin microparticles, by spray-drying method [ 31 ]. In this regard, reinforcement of biodegradable TPS/bentonite clay nanocomposite film containing VB is of particular interest to assess their potential use as active packaging systems by preserving and improving the functionality of encapsulated VB. However, to the best of our knowledge, no work has been reported on the simultaneous incorporation of vitamin B 2 and bentonite clay in starch-based films. The main goal of the present work was to evaluate the physicochemical properties of the nanocomposites based on TPS loaded with various content of bentonite clay and VB. The nanocomposite films were obtained using the solvent casting method. Furthermore, the effects of bentonite clay (BC) and vitamin B 2 were investigated on the mechanical and thermal properties of TPS films, and their stability in the water as well as the release behavior. 2. Experimental 2.1. Materials Native corn starch Meritena® 100 was supplied by Brenntag (Bratislava, Slovakia). The water content determined by drying in an oven at 100°C for 5 h was around 12 wt.%. Bentonite clay (BC) was purchased from Southern Clay Brick Co. (Texas, USA). Glycerol and vitamin B 2 (VB) were purchased from Merck (Darmstadt, Germany). Double distilled water was used in all experiment processes. 2.2. Preparation of TPS-bentonite clay nanocomposites reinforced with vitamin B 2 First, bentonite clay (BC) at 3 and 10 parts based on the dry weight of starch (php) were dispersed in water by sonication at ambient temperature for 10 min. Then, each suspension was added separately to a mixture containing starch, glycerol and water according to the receipt summarized in Table 1 . In the next step, to prepare vitamin B 2 -reinforced samples, 1, 5, and 10 php of vitamin (based on dry weight of starch) were added to starch and starch-BC solutions. Afterward, further processing of mixtures was performed in the same way as follows. To obtain gelatinized starch, the mixture of starch, BC, glycerol, vitamin B 2 , and water was heated at 70°C for 15 min under continuous stirring. All the mixtures were homogenized by sonication for 30 min, and then, casted into circular molds,, and dried at 45°C in an oven for 24 h. To consider the effects of VB and BC on the properties of TPS films, two series of composite films with and without BC and VB were prepared. Table 1 summarizes the composition and sample code of each formulation. Table 1 Sample codes and composition of the TPS composites filled with bentonite clay (BC) and vitamin B 2 (VB). The numbers after BC and VB in the sample codes represent the amount of BC and VB in php, respectively. Sample code Starch (g) Glycerol (g) BC (g) VB (g) TPS 100 50 0 0 TPS/BC3 100 50 3 0 TPS/BC10 100 50 10 0 TPS/VB1 100 50 0 1 TPS/VB5 100 50 0 5 TPS/VB10 100 50 0 10 TPS/BC3/VB1 100 50 3 1 TPS/BC3/VB5 100 50 3 5 TPS/BC3/VB10 100 50 3 10 TPS/BC10/VB1 100 50 10 1 TPS/BC10/VB5 100 50 10 5 TPS/BC10/VB10 100 50 10 10 2.3. Physico-chemical characterization 2.3.1. Elemental analysis Elemental analysis was performed to measure carbon, nitrogen and hydrogen contents using a Thermo scientific Flash 2000 CHN Elemental Analyzer. 2.3.2. Mechanical properties The mechanical properties of the prepared films were determined using an Instron 3365 universal testing machine (Instron, Massachusetts, USA). Before measurement, the dog-bone shaped specimens were punched by manual toggle press equipment with a 3.5 × 30 mm dimension of area being deformed during the test (the thickness of approximately 1 mm was exactly measured by a digital caliper). Tests were carried out at a speed of 1 mm·min –1 with deformation up to 1% and at a speed of 50 mm·min –1 at higher deformations, according to ASTM D638. The mean values and standard deviations were calculated of 7 specimens for all parameters. 2.3.3. Dynamic mechanical thermal analysis (DMTA) Dynamic mechanical thermal analysis (DMTA) was conducted using DMA Q800 (TA Instruments, Germany) equipment. Tests were performed in tensile mode at a frequency of 10 Hz and an amplitude of 20 µm. These measurements were performed to determine the storage modulus (Gʹ), loss modulus (Gʺ), and tangent of the loss angle (tan δ) of TPS composite samples (ca. 10 × 7 × 1 mm 3 ). The temperature range was fixed from − 20 to 120°C with a heating rate of 2°C·min − 1 . 2.3.4. Thermogravimetric analysis (TGA) Thermal stability and degradation profile of the prepared TPS samples were studied using, NETZSCH STA 449F3, TGA-50 from 20 to 800°C at 10 K‧min –1 rate under a nitrogen atmosphere. 2.3.5. Water uptake Water uptake ratio of the prepared samples was determined using the gravimetric method at an ambient temperature. The samples were cut into discs with a diameter of 2 cm and dried at 105°C in an oven to reach the constant weight (W d ). The dried samples were then soaked in distilled water for 24 h to reach the equilibrium state. The wet weight of the swollen samples was measured after the removal of excess water from the surface of the films (W s ). The Water uptake ratio (WU) was calculated by the Eq. 1. \(WU \left(\%\right)=\frac{{W}_{s}-{W}_{d}}{{W}_{d}}\times 100\) (Eq. 1) where W s and W d are the weight of the swollen and dried samples, respectively. 2.3.6. Weight loss in water The specimens of each sample were measured with the dimension of 2 × 2 cm (W 1 ) and dried at 105°C for 5 h and weighed again (W 2 ). Then, triplicate specimens of each TPS sample were immersed in deionized water and maintained at ambient conditions for 24 h. After filtering out, the insoluble portion was dried in an oven at 60°C for 24 h and weighed (W 3 ). The moisture content (MC) and percentage of the weight loss in water (W L ) were calculated according to equations 2 and 3, respectively. \(MC \left(\text{\%}\right)=\frac{{W}_{1}- {W}_{2} }{{W}_{2}}\times 100\) (Eq. 2) \({W}_{\text{L}} \left(\text{\%}\right)=\left(\frac{{W}_{2}- {W}_{3} }{{W}_{2}}\right)\times 100\) (Eq. 3) 2.3.7. In vitro release of vitamin B 2 In vitro vitamin release from the prepared films was studied in phosphate buffer (PBS) solution (pH 7.4). Briefly, 200 mg of the vitamin B 2 -loaded TPS without and with different contents of BC were suspended into the vials containing 20 mL of PBS, separately. At regular time intervals, 3 mL of the solution was taken and its absorbance was recorded at 446 nm using a UV-Vis spectrophotometer (Cary 50 UV-Vis spectrophotometer, Varian, Australia). The fresh solvent with the same volume was immediately injected into the harvested vials. The cumulative release of the vitamins from the prepared films was calculated by Eq. 4. \(\text{c}\text{u}\text{m}\text{u}\text{l}\text{a}\text{t}\text{i}\text{v}\text{e} \text{r}\text{e}\text{l}\text{e}\text{a}\text{s}\text{e} \left(\text{\%}\right)=\frac{{M}_{t}}{{M}_{0}}\times 100\) (Eq. 4) where M t is the amount of released VB from the TPS at time t and M 0 is the amount of VB in the TPS samples. The experiments were performed in triplicate, and the results were recorded as an average with an error bar that represents the relative standard deviation. 3. Results And Discussion In short, in this study, thermoplastic films were synthesized based on starch biopolymer. Bentonite clay was added as reinforcement to improve the physic-chemical characteristics of the TPS. This casted film was fortified by VB. The individual and simultaneous effects of BC and VB were studied on the tensile strength of nanocomposites. Thermal stability and degradation profiles of the prepared nanocomposites were studied by TGA. The swelling degree and weight loss of the synthesized nanocomposites were investigated after individual/or simultaneous incorporation of BC and VB. Finally, the release profile of VB was evaluated from the nanocomposite containing various amounts of BC. 3.1. CHN elemental analysis CHN analysis was performed to confirm the presence of VB in TPS/BC nanocomposites. Carbon, hydrogen, and nitrogen contents of the TPS, TPS/BC, TPS/VB, and TPS/BC/VB were measured by CHN elemental analysis, and the results are summarized in Table 2 . The results show the presence of nitrogen atoms in the TPS/VB10 and TPS/BC10/VB10 samples, while the nitrogen in TPS and TPS/BC10 are equal to zero. This confirms the presence of VB in the VB-fortified samples. Table 2 CHN elemental analysis results of the TPS samples containing bentonite clay (BC) and vitamin B 2 (VB). Sample C N H TPS 39.41 ± 0.20 0 7.0 ± 0.2 TPS/BC10 37.33 ± 0.13 0 6.7 ± 0.1 TPS/VB10 40.69 ± 0.17 1.10 ± 0.03 6.81 ± 0.04 TPS/BC10/VB10 38.15 ± 0.21 0.99 ± 0.1 6.69 ± 0.15 3.2. Mechanical properties The values of mechanical properties, including tensile stress, elongation at the break, and Young’s modulus are summarized in Table 3 . Moreover, Fig. 1 represents the dependence of BC and VB contents on the ultimate tensile strength and strain at break of the TPS nanocomposite films. Considering the effect of BC, it is seen that the tensile strength and Young’s modulus of the TPS nanocomposite film increase slightly with rising content of BC compared to the neat TPS film. Moreover, the incorporation of BC leads to the increase in the resistance of the nanocomposite film to elongation. This observation is due to the strong interaction between starch and BC, which limits the interactions of water and glycerol to interact with starch. Therefore, in contrast to glycerol (as a plasticizer), BC plays an anti-plasticization role. These findings were consistent with the previous published data [ 32 – 35 ]. The dispersion of clay nanolayers in the TPS matrix may optimize the number of available reinforcing elements to carry the applied load and deflecting cracks, resulting in such mechanical strength increase [ 9 , 36 ]. Table 3 Mechanical properties, including tensile strength, elongation at break, and Young’s modulus of the TPS nanocomposites. The concentration is shown in php as the number after each code. Sample Code Tensile Strength (MPa) Elongation at Break (%) Young’s Modulus (MPa) TPS 5.4 ± 0.7 73.8 ± 11.9 51.2 ± 23.7 TPS/BC3 5.5 ± 0.2 72.7 ± 4.6 47.7 ± 2.8 TPS/BC10 6.3 ± 0.7 49.7 ± 7.0 138.7 ± 60.4 TPS/VB1 4.9 ± 0.4 89.5 ± 13.8 50.0 ± 13.9 TPS/VB5 3.8 ± 1.0 57.5 ± 11.8 37.3 ± 8.4 TPS/VB10 3.4 ± 0.7 41.4 ± 7.4 28.4 ± 1.8 TPS/BC3/VB1 5.7 ± 0.3 81.1 ± 5.8 54.1 ± 5.2 TPS/BC3/VB5 7.6 ± 1.4 62.4 ± 12.1 205.6 ± 46.1 TPS/BC3/VB10 5.4 ± 0.5 71.1 ± 2.5 88.5 ± 26.1 TPS/BC10/VB1 6.6 ± 1.4 43.7 ± 9.1 159.9 ± 72.6 TPS/BC10/VB5 8.0 ± 2.3 39.3 ± 8.6 246.2 ± 73.4 TPS/BC10/VB10 7.0 ± 0.2 47.9 ± 3.5 169.6 ± 22.7 The corresponding results of mechanical properties for the TPS films containing vitamin B 2 can be seen in Fig. 1 and Table 3 . These results exhibit a decrease in tensile strength and Young’s modulus for the materials with various amounts of vitamin B 2 compared to the neat TPS film. This behavior indicates the presence of more hydrophilic groups in the samples as a function of higher content of VB. According to the literature [ 37 , 38 ], more absorbed humidity can act as an additional plasticizer. Herein, the lower tensile strength of the vitamin-fortified TPS (TPS-VB1, TPS-VB5, and TPS-VB10) films with the higher vitamin B 2 content can be attributed to the existence of more pores in the TPS matrix. However, it was observed that the incorporation of BC into the TPS/VB film led to a substantial increase in tensile strength and Young’s modulus. The explanation of this phenomenon may consist of two performances of silicate layers, including the reinforcing effect of clay particles and blocking of the pores created by the addition of vitamin B 2 . The most important role of vitamin concentration was demonstrated in the mechanical properties by the values of tensile strength for 5 php VB. This increase may have been facilitated by interactions among starch chain, clay particles and VB, in which many factors, including the ratio of amylose-amylopectin in starch, dispersion and exfoliation of BC, and the amount of VB can play a critical role [ 9 ]. It is well-known that plasticizers are also essential additives since they can improve the flexibility and handling of films, maintain integrity, and avoid pores and cracks in the polymeric matrix [ 39 , 40 ]. From this point of view, the action of VB as a plasticizer for starch molecules should be considered as another factor to explain this result. Consequently, use of an optimum amount of VB and BC can cause synergistic effects on mechanical properties. This explanation is supported by the shape of the stress–strain curves for the TPS nanocomposites displayed in Fig. 2 . 3.3. Dynamic mechanical thermal analysis (DMTA) The mechanical response of the sample under a small harmonic force was recorded in DMTA measurements. Also, the viscoelastic response of polymers, which is associated with the molecular motions related to internal changes of the polymers, was evaluated by this technique. Relaxation processes undergoing in the studied samples during gradual heating can be detected through inflection points in storage modulus as well as maxima in both the loss modulus and the damping factor temperature dependences as some deal of received energy dissipates through viscous movement [ 41 ]. The storage modulus obtained from the DMTA analysis of the TPS nanocomposite films are shown in Fig. 3 . The storage modulus (G ʹ ) of samples containing BC and VB was higher than the neat TPS film. It has been known that the storage modulus was associated with stiffness, which was affected by the glass transition temperature ( T g ), morphology, and structure of the polymer matrix. This observation may be related to the interactions among starch chain, clay particles, and VB, which was indicated by the mechanical properties (Fig. 1 ). Figure 4 represents the tan δ curves as a function of temperature. Tan δ is the viscoelasticity index of the material, which is usually defined as a damping term. The temperatures of the appearance of maximum tan δ determined from data in Fig. 4 , are displayed in Table 4 . Theoretically, in tan δ temperature dependences of TPS with higher plasticizer contents, two relaxation peaks usually appear which reflected the partial miscibility of starch and glycerol. The first one close to the glass transition temperature of the plasticizer is related to the glycerol-rich domains, in which the mobility of starch chains is controlled by glycerol molecules motion. The second relaxation temperature corresponds to the starch-rich domains [ 38 , 42 ]. As seen in Table 4 , the main relaxation of the starch-rich phase shifted to the higher temperatures with rising vitamin B 2 content for TPS/BC/VB nanocomposites. This observation can be explained by the interaction among the starch, glycerol, BC, and VB, thus restricting the mobility of the starch chains. Therefore, the macromolecules are restricted in motion so that their segmental relaxation is observed at higher temperatures [ 43 , 44 ]. Table 4 shows that the relaxation temperature for TPS/VB samples increased, reaching a maximum for TPS/VB5 sample, then slightly decreased for TPS/VB10. This trend can be attributed to the existence of high amounts of hydrophilic groups in the TPS/VB10 sample. Interestingly, in the case of TPS nanocomposite containing 5 php of VB, a broad relaxation peak was observedwith a higher intensity compared to the other samples, indicating strong interaction among the components. These results were also supported by a substantial increase in both tensile strength and Young’s modulus. Table 4 Temperatures of the appearance of maximum tan δ determined from data in Fig. 3 b. Sample code peak T (°C) TPS 19.3 TPS/VB1 19.2 TPS/VB5 24.6 TPS/VB10 23.2 TPS/BC3 13.6 TPS/BC3/VB1 13.6 TPS/BC3/VB5 14.2 TPS/BC3/VB10 16.9 TPS/BC10 19.3 TPS/BC10/VB1 14.0 TPS/BC10/VB5 15.3 TPS/BC10/VB10 17.0 3.4. Thermogravimetric analysis Thermal stability and degradation profile of the prepared samples were evaluated by TGA. Figure 5 shows the thermal behavior of bentonite-reinforced nanocomposites containing vitamin B 2 . The initial weight loss observed in the temperature range of 20–200°C is attributed to the elimination of unbonded and bonded water molecules [ 45 ]. Two distinct stages of mass loss from 220–350°C correspond to the degradation of starch and vitamin B 2 , verifying the compatibility of vitamin with starch. Starch was found to degrade between 300–500°C [ 46 ]. It was reported that vitamin B 2 firstly decomposed at ribo block by losing three molecules of water resulting in the formation of alcohol, ethylene, and acetaldehyde. The second weight loss for vitamin B 2 at a temperature over 250°C is attributed to the degradation of flavin block which leads to the formation of CO 2 , phenol, and char [ 47 , 48 ]. The temperatures corresponding to the weight losses of 10%, 50%, 70%, and 90% are presented in Table 5 . The onset of decomposition for TPS/BC3/VB5, TPS/BC3/VB10, TPS/BC10/VB1, TPS/BC10/VB5, and TPS/BC10/VB10 is occurred at around 230, 232, 245, 234, and 238°C, respectively. As proved in thermal patterns, increase of the amount of bentonite from 3 php to 10 php resulted in increase of the thermal stability of nanocomposites. These findings are in agreement with the previous reports on improving the thermal resistance of nanocomposites in the presence of bentonite [ 49 , 50 ] or MMT [ 51 , 52 ]. Clay-reinforced nanocomposites were found to form char with a multilayered carbonaceous silicate structure during pyrolysis. This leads to preserving its structure in the polymer matrix at temperatures over 500°C. The carbonaceous-silicate char formed on the film’s surface acts as an insulator and delays the release of components produced during decomposition [ 53 ]. As revealed in Fig. 5 , inorganic residue increased for the nanocomposites containing 10 php BC compared to those containing 3 php BC. This increment at around 800°C further approves the successful incorporation of BC into the starch matrix. Table 5 Temperatures corresponded to weight losses of 10%, 50%, 70%, and 90% Sample T (°C) 10% 50% 70% 90% TPS/BC3/VB5 230.3 307.1 324.3 917.5 TPS/BC3/VB10 233.0 307.1 324.4 912.2 TPS/BC10/VB1 245.0 313.0 332.0 956.0 TPS/BC10/VB5 232.8 312.3 326.0 943.4 TPS/BC10/VB10 238.3 312.4 329.5 948.4 3.5. Swelling behaviors and weight loss The effect of BC and VB was studied on the swelling behavior of TPS and the results are presented in Fig. 6 . As shown, the swelling ratio of TPS film decreased by incorporating 3 php of BC. This finding may be ascribed to the interaction between BC and the polymer, which prevents water diffusion into the nanocomposite. In contrast, the swelling ratio of TPS film increased with the addition of 10 php BC (TPS/BC10). It was reported that the interaction between starch and BC increased the surface hydrophilicity facilitating the diffusion of water molecules [ 54 ]. This behavior may be concluded from the increased porosity of the composites. Moreover, the high specific surface area of the nanoplatelets of bentonite, provides the perfect contact with starch which leads to a reduction in the permeability of the composites [ 55 ]. The swelling ratio for TPS films reinforced with 1 php and 5 php of vitamin B 2 showed an increase compared to TPS film. This result can be attributed to the higher affinity of vitamin B 2 to absorb water, which enhances the hydrophilicity of vitamin-reinforced TPS composite. This finding is consistent with the published data on the increase of the swelling degree of riboflavin-loaded chitosan [ 56 ]. Whereas, further increase of vitamin B 2 (10 php) caused a decrease in the swelling ratio. The reason for the decrease may consist in the effective reactions between functional groups of starch and vitamin, which formed a more compact structure, limiting the penetration of water molecules into the matrix [ 57 ]. Since solubility is determined as the main criterion for measuring the water resistance of the prepared films, the degradation behavior of TPS-based nanocomposites was studied by measuring their solubility after regular incubation times (10, 24, and 48 hours) in PBS (pH 7.4) at 37°C. As shown in Fig. 7 , the weight loss for all of the prepared samples increased with increasing incubation time. It was also revealed that the addition of both BC and VB in TPS films influenced the degradation rate of the nanocomposite. The incorporation of BC into TPS film significantly decreased the solubility of the nanocomposite, which could hinder the water penetration into the matrix. This result may occur due to the formation of strong hydrogen bonds between hydroxyl groups of BC and the hydroxyl groups of starch, which may increase the cohesiveness of the nanocomposite matrix and decrease their water sensitivity [ 58 ]. 3.6. Release profile of vitamin B 2 from nanocomposite The release profiles of VB from the prepared nanocomposites during 96 h are presented in Fig. 8 . At a glance, Fig. 8 shows that the release of VB from nanocomposites depends on the content of BC, the higher BC content, the slower VB release. The released VB from TPS/VB1 was 52%, which decreased to 42% and 27% in the presence of 3 and 10 php BC, respectively. On the other hand, around 80% of VB was released from TPS/VB5, while the release content reached 64% and 52% after incorporating 3 and 10 php BC, respectively. The incorporation of 3 and 10 php of BC into TPS/VB10 resulted in decrease of the vitamin release from 60–50% and 46%, respectively. It is also clear that more sustained VB release was attained in BC-reinforced TPS/VB. This behavior might be ascribed to the barrier properties of the clay, which hinders the fast penetration of hydrophilic VB into aqueous media by creating a tortious path, as described by the effect of clay on the release of VB and various drugs in the literature [ 59 – 62 ]. Conclusions This work provided new insights into developing thermoplastic starch/bentonite clay (TPS/BC) nanocomposite fortified with vitamin B 2 (VB) toward understanding a correlation between the starch/bentonite clay and VB. Therefore, the effect of VB on the physicochemical properties of TPS/bentonite clay nanocomposite films as well as the vitamin release behavior were evaluated. Incorporating higher amounts of BC and VB into the TPS matrix results in a substantial increase in tensile strength and Young’s modulus, while decreasing the corresponding elongation at break. This phenomenon indicates the reinforcing effect of clay particles and blocking the pores created by addition of VB, which could show synergetic impact at a specific concentration of BC and VB. The nanocomposites containing 5 parts based on the dry weight of starch (php) VB e.g., TPS/BC3/VB5 and TPS/BC10/VB5 exhibited the highest increase in tensile strength and Young’s modulus. Moreover, the nanocomposites demonstrated an increase in the main relaxation of the starch-rich phase with the rising VB content, as revealed by the dynamic mechanical thermal analysis (DMTA) results, confirming the restriction of the mobility of the starch chains. The TPS nanocomposites reinforced with 1 php and 5 php VB showed an increase in water uptake compared to the TPS film, which is attributed to the higher affinity of VB to absorb water due to enhanced hydrophilicity of vitamin-reinforced TPS composite. The release studies indicate that the TPS nanocomposites with a higher BC content resulted in a lower amount and delayed vitamin release, indicating good potential for vitamin delivery purposes. Declarations Acknowledgment The authors express their gratitude to the Endocrinology and Metabolism Research Center of Kerman University of Medical Sciences and Shahid Bahonar University of Kerman. This work was also supported by the Slovak Research and Development Agency under the contract number APVV-18-0480 and VEGA Grant Agency under contract number 2/0121/23. This work is the result of the project implementation CEMBAM – Centre for Medical Bio-Additive Manufacturing and Research, ITMS2014+: 313011V358 and Advanced bioactive hydrogel scaffolds for regenerative medicine (ABSACARM), ITMS2014+: 313011BWL6 supported by the Operational Programme Integrated Infrastructure funded by the European Regional Development Fund. Competing interests: The authors declare no competing interests. References H. Peidayesh, A. Heydari, K. Mosnackova, I. Chodak, In situ dual crosslinking strategy to improve the physico-chemical properties of thermoplastic starch, Carbohydr Polym 269 (2021) 118250. H. Peidayesh, Z. Ahmadi, H.A. Khonakdar, M. Abdouss, I. 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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-2587534","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":176100924,"identity":"d066db47-f017-4cdd-ab53-9955e5c357f7","order_by":0,"name":"Abolfazl 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1","display":"","copyAsset":false,"role":"figure","size":325557,"visible":true,"origin":"","legend":"\u003cp\u003eDependence of bentonite clay (BC) and vitamin B\u003csub\u003e2\u003c/sub\u003e (VB) contents on (a) ultimate tensile strength and (b) strain at break of the TPS nanocomposite films.\u003c/p\u003e","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-2587534/v1/38b5d93d8c48bf510d8ba549.jpeg"},{"id":33091030,"identity":"56e74bdc-86a7-4b52-8cfa-9adb0e45c1b3","added_by":"auto","created_at":"2023-02-17 14:42:58","extension":"jpeg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":477646,"visible":true,"origin":"","legend":"\u003cp\u003eStress–strain curves for (a) thermoplastic starch (TPS)/bentonite clay (BC) nanocomposite and TPS/vitamin B\u003csub\u003e2\u003c/sub\u003e, (b) TPS/BC3 with various contents of vitamin B\u003csub\u003e2\u003c/sub\u003e, and (c) TPS/BC10 with various contents of vitamin B\u003csub\u003e2\u003c/sub\u003e. The concentration is shown in php as the number after each code.\u003c/p\u003e","description":"","filename":"floatimage2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-2587534/v1/1889a49212d3d5f88567a40a.jpeg"},{"id":33089465,"identity":"d8a04243-fa14-4e4a-97a6-1cfeb33e307f","added_by":"auto","created_at":"2023-02-17 14:34:58","extension":"jpeg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":431084,"visible":true,"origin":"","legend":"\u003cp\u003eTemperature dependences of the storage modulus for the (a) TPS/VB, (b) TPS/bentonite clay (BC) 3 with various contents of vitamin B\u003csub\u003e2\u003c/sub\u003e (VB), and (c) TPS/BC10 with various contents of VB. The concentration is shown in php as the number after each code.\u003c/p\u003e","description":"","filename":"floatimage3.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-2587534/v1/906e12ee78781d1b297e73db.jpeg"},{"id":33091028,"identity":"fec4c68e-d80d-4d55-9e43-dedd61bd07a1","added_by":"auto","created_at":"2023-02-17 14:42:58","extension":"jpeg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":356181,"visible":true,"origin":"","legend":"\u003cp\u003eTemperature dependences of the tan δ for the (a) TPS/VB, (b) TPS/bentonite clay (BC) 3 with various contents of vitamin B\u003csub\u003e2\u003c/sub\u003e (VB), and (c) TPS/BC10 with various contents of VB. The concentration is shown in php as the number after each code.\u003c/p\u003e","description":"","filename":"floatimage4.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-2587534/v1/b646313658d02c3f2016357d.jpeg"},{"id":33089458,"identity":"bd6355bc-97f6-4a1d-8389-b7f29ad22bd5","added_by":"auto","created_at":"2023-02-17 14:34:58","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":61475,"visible":true,"origin":"","legend":"\u003cp\u003eTGA thermograms of TPS composite samples filled with various contents of bentonite clay (BC) and vitamin B\u003csub\u003e2\u003c/sub\u003e (VB).\u003c/p\u003e","description":"","filename":"5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-2587534/v1/095e71ebadd311f1ffcc12b9.jpg"},{"id":33091027,"identity":"c6125165-c100-4641-b0ea-a6adad5af6e0","added_by":"auto","created_at":"2023-02-17 14:42:58","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":147436,"visible":true,"origin":"","legend":"\u003cp\u003eSwelling capacity of TPS nanocomposite films filled with various contents of bentonite clay (BC) and vitamin B\u003csub\u003e2\u003c/sub\u003e (VB) in water measured during 24 h. The concentration is shown in php as the number after each code.\u003c/p\u003e","description":"","filename":"6.jpg","url":"https://assets-eu.researchsquare.com/files/rs-2587534/v1/d1b33ee50ffa5e554ac0a14a.jpg"},{"id":33089462,"identity":"e661cd9a-7095-4a83-8052-0a117018981a","added_by":"auto","created_at":"2023-02-17 14:34:58","extension":"jpg","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":154090,"visible":true,"origin":"","legend":"\u003cp\u003eWeight loss (in %) of the TPS nanocomposite filled with various contents of bentonite clay (BC) and vitamin B\u003csub\u003e2\u003c/sub\u003e (VB) in water for 48 h. The concentration of VB is shown in php as the number after each code.\u003c/p\u003e","description":"","filename":"7.jpg","url":"https://assets-eu.researchsquare.com/files/rs-2587534/v1/ea8ff867de4a7caf2084a065.jpg"},{"id":33091029,"identity":"7bb39b45-74b5-490f-be89-87415572ae21","added_by":"auto","created_at":"2023-02-17 14:42:58","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":53952,"visible":true,"origin":"","legend":"\u003cp\u003eCumulative release of VB from thermoplastic starch/bentonite clay nanocomposite in PBS (pH 7.4). Each graph shows the release of vitamins (in %) from TPS nanocomposite containing various contents of BC in php and the same content of VB. The concentration of VB is shown in php as the number after each code.\u003c/p\u003e","description":"","filename":"Onlinefloatimage8.png","url":"https://assets-eu.researchsquare.com/files/rs-2587534/v1/da849c270c2c38637ca81ee9.png"},{"id":33091032,"identity":"ef35a428-5288-4a47-b0c6-a3b02d8df78d","added_by":"auto","created_at":"2023-02-17 14:43:05","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1130287,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-2587534/v1/5dcbc8f9-624a-4254-8fe7-5110ba664b6d.pdf"}],"financialInterests":"","formattedTitle":"\u003cp\u003e\u003cstrong\u003eThermoplastic starch/bentonite clay nanocomposite reinforced with vitamin B\u003c/strong\u003e\u003csub\u003e\u003cstrong\u003e2\u003c/strong\u003e\u003c/sub\u003e\u003cstrong\u003e: Physicochemical characteristics and release behavior\u003c/strong\u003e\u003c/p\u003e","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eStarch, as one of the most promising candidates in the biopolymer industry, has been widely considered, since it is completely biodegradable, available from renewable resources, abundant in nature, and cost-effective. However, high brittleness is one of the disadvantages, which is seen in native starch as a plastic material. Therefore, by adding a suitable plasticizer, it can be converted to thermoplastic starch (TPS) under special thermal and shear conditions [\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. This plastification process leads to the destruction of crystallinity and increase in chain flexibility [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. However, the main shortcoming of TPS is the recrystallization phenomena caused by its hydrophilic character, as it leads to unsatisfactory mechanical properties during storage [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. The incorporation of filler in the polymer matrix can be considered as one of the most practical strategies to improve the mechanical properties of starch-based films, as well as one of the important approaches to develop barrier properties to prevent the penetration of moisture and oxygen [\u003cspan additionalcitationids=\"CR6\" citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Layered silicates have proven to be effective reinforcing agents to improve barrier and mechanical properties of the polymer matrix. The addition of a definite amount of inorganic silicate layers not only provides a barrier for oxygen and water molecules but also, increases strength and modulus strength [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. The layered silicates used in nanocomposites include montmorillonite, bentonite, hectorite, saponite, and other modified cationic compounds. Bentonite is one of the most commonly used clays due to its low cost, availability in large quantities, and its environmentally benign nature [\u003cspan additionalcitationids=\"CR10\" citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Nanocomposite films incorporating bioactive molecules such as antimicrobials, antioxidants, and vitamins received great attention in the cosmetic, pharmaceutical, nutraceutical, and food industries [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Among them, vitamins are organic substances that are classified into fat-soluble (vitamin A, vitamin D, vitamin E, vitamin K, and vitamin B\u003csub\u003e2\u003c/sub\u003e) and water-soluble (vitamin C and the B-complex vitamins such as vitamin B\u003csub\u003e6\u003c/sub\u003e, vitamin B\u003csub\u003e12\u003c/sub\u003e, and folate) ones [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eVitamin B\u003csub\u003e2\u003c/sub\u003e, also known as riboflavin, is one of the essential water-soluble vitamins for humans [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Vitamin B\u003csub\u003e2\u003c/sub\u003e plays an important role in the metabolism of carbohydrates, lipids, and proteins and is crucial for the generation of biological energy in the electron-transport system. Vitamin B\u003csub\u003e2\u003c/sub\u003e is an abundant, naturally occurring chemical existing in various food like milk, dairy products, fish, meats, fruit, and vegetables [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. This vitamin is also essential for living organisms and plays a vital role in the production and regulation of certain hormones, and the formation of red blood cells [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Vitamin B\u003csub\u003e2\u003c/sub\u003e is known as a photosensitizer, which can produce reactive oxygen species (ROS) at a certain wavelength leading to the deactivation of malignant cells and pathogenic microorganisms [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. Sufficient dietary or supplemental intake of vitamin B\u003csub\u003e2\u003c/sub\u003e has been reported to provide anti-oxidant, anti-aging, anti-inflammatory, and anti-cancer properties [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Hair loss, skin crack, depression, blurred vision, swollen mouth, and tongue are the most famous symptoms of vitamin B\u003csub\u003e2\u003c/sub\u003e deficiency [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. The human body is unable to synthesize vitamin B\u003csub\u003e2\u003c/sub\u003e and it should be supplied in dietary [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Vitamins are sensitive to light, heat and oxidations and so they should be preserved from these destructive agents.\u003c/p\u003e \u003cp\u003eIn this context, encapsulation of vitamin B\u003csub\u003e2\u003c/sub\u003e in the polymer matrix has emerged as a promising strategy to overcome the above obstacles [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Vitamins are encapsulated via different methods, including a layer-by-layer technique, electrospinning/electrospraying, freeze-drying, coprecipitation, solvent casting, spray drying, and complex coacervation [\u003cspan additionalcitationids=\"CR22\" citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. Lee et al. prepared hyaluronic acid hydrogels via visible light-induced thiol-ene reaction in the presence of crosslinked riboflavin. Delayed gelation is promising for in situ medical applications, such as ophthalmology and stomatology [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. Microencapsulation of vitamin B\u003csub\u003e2\u003c/sub\u003e was conducted in alginate hydrogel coated with chitosan. Results demonstrated the encapsulation efficiency depending on concentration of both polymers [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. Chitosan-based printed materials were synthesized for efficient delivery of vitamin B\u003csub\u003e2\u003c/sub\u003e [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. The initial burst followed by slow drug release was concluded in the case of VB encapsulated into hydrophobic epichlorohydrin-crosslinked β-cyclodextrin nanofibers [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. The release of uncoated riboflavin and ethyl cellulose-coated barium alginate beads in the media with different pH values was studied by Bajpai and Sharma. The slower drug release was observed for the coated beads [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. Vitamin B\u003csub\u003e2\u003c/sub\u003e was also loaded into starch/polyacrylic acid based interpenetrating network. This delivery system was suggested for colon-targeted drug-delivery [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e]. The colored silk fabric, bearing frame retardant and antibacterial properties, was prepared by layer-by-layer electrostatic self-assembly of chitosan and VB on silk fabric [\u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e]. The layered encapsulation of vitamin B\u003csub\u003e2\u003c/sub\u003e and β-carotene was studied in alginate multilayered gel microspheres for their simultaneous delivery to the intestinal tract [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e]. Vitamin B\u003csub\u003e2\u003c/sub\u003e and vitamin B\u003csub\u003e3\u003c/sub\u003e were encapsulated into chitosan, modified chitosan, gum arabic, maltodextrin, sodium alginate, and pectin microparticles, by spray-drying method [\u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn this regard, reinforcement of biodegradable TPS/bentonite clay nanocomposite film containing VB is of particular interest to assess their potential use as active packaging systems by preserving and improving the functionality of encapsulated VB. However, to the best of our knowledge, no work has been reported on the simultaneous incorporation of vitamin B\u003csub\u003e2\u003c/sub\u003e and bentonite clay in starch-based films. The main goal of the present work was to evaluate the physicochemical properties of the nanocomposites based on TPS loaded with various content of bentonite clay and VB. The nanocomposite films were obtained using the solvent casting method. Furthermore, the effects of bentonite clay (BC) and vitamin B\u003csub\u003e2\u003c/sub\u003e were investigated on the mechanical and thermal properties of TPS films, and their stability in the water as well as the release behavior.\u003c/p\u003e"},{"header":"2. Experimental","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1. Materials\u003c/h2\u003e \u003cp\u003eNative corn starch Meritena\u0026reg; 100 was supplied by Brenntag (Bratislava, Slovakia). The water content determined by drying in an oven at 100\u0026deg;C for 5 h was around 12 wt.%. Bentonite clay (BC) was purchased from Southern Clay Brick Co. (Texas, USA). Glycerol and vitamin B\u003csub\u003e2\u003c/sub\u003e (VB) were purchased from Merck (Darmstadt, Germany). Double distilled water was used in all experiment processes.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2. Preparation of TPS-bentonite clay nanocomposites reinforced with vitamin B\u003csub\u003e2\u003c/sub\u003e\u003c/h2\u003e \u003cp\u003eFirst, bentonite clay (BC) at 3 and 10 parts based on the dry weight of starch (php) were dispersed in water by sonication at ambient temperature for 10 min. Then, each suspension was added separately to a mixture containing starch, glycerol and water according to the receipt summarized in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. In the next step, to prepare vitamin B\u003csub\u003e2\u003c/sub\u003e-reinforced samples, 1, 5, and 10 php of vitamin (based on dry weight of starch) were added to starch and starch-BC solutions. Afterward, further processing of mixtures was performed in the same way as follows. To obtain gelatinized starch, the mixture of starch, BC, glycerol, vitamin B\u003csub\u003e2\u003c/sub\u003e, and water was heated at 70\u0026deg;C for 15 min under continuous stirring. All the mixtures were homogenized by sonication for 30 min, and then, casted into circular molds,, and dried at 45\u0026deg;C in an oven for 24 h. To consider the effects of VB and BC on the properties of TPS films, two series of composite films with and without BC and VB were prepared. Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e summarizes the composition and sample code of each formulation.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eSample codes and composition of the TPS composites filled with bentonite clay (BC) and vitamin B\u003csub\u003e2\u003c/sub\u003e (VB). The numbers after BC and VB in the sample codes represent the amount of BC and VB in php, respectively.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSample code\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eStarch (g)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eGlycerol (g)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eBC (g)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eVB (g)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/BC3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/BC10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/VB1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/VB5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/VB10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/BC3/VB1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/BC3/VB5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/BC3/VB10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/BC10/VB1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/BC10/VB5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/BC10/VB10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e10\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3. Physico-chemical characterization\u003c/h2\u003e \u003cdiv id=\"Sec6\" class=\"Section3\"\u003e \u003ch2\u003e2.3.1. Elemental analysis\u003c/h2\u003e \u003cp\u003eElemental analysis was performed to measure carbon, nitrogen and hydrogen contents using a Thermo scientific Flash 2000 CHN Elemental Analyzer.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section3\"\u003e \u003ch2\u003e2.3.2. Mechanical properties\u003c/h2\u003e \u003cp\u003eThe mechanical properties of the prepared films were determined using an Instron 3365 universal testing machine (Instron, Massachusetts, USA). Before measurement, the dog-bone shaped specimens were punched by manual toggle press equipment with a 3.5 \u0026times; 30 mm dimension of area being deformed during the test (the thickness of approximately 1 mm was exactly measured by a digital caliper). Tests were carried out at a speed of 1 mm\u0026middot;min\u003csup\u003e\u0026ndash;1\u003c/sup\u003e with deformation up to 1% and at a speed of 50 mm\u0026middot;min\u003csup\u003e\u0026ndash;1\u003c/sup\u003e at higher deformations, according to ASTM D638. The mean values and standard deviations were calculated of 7 specimens for all parameters.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section3\"\u003e \u003ch2\u003e2.3.3. Dynamic mechanical thermal analysis (DMTA)\u003c/h2\u003e \u003cp\u003eDynamic mechanical thermal analysis (DMTA) was conducted using DMA Q800 (TA Instruments, Germany) equipment. Tests were performed in tensile mode at a frequency of 10 Hz and an amplitude of 20 \u0026micro;m. These measurements were performed to determine the storage modulus (Gʹ), loss modulus (Gʺ), and tangent of the loss angle (tan δ) of TPS composite samples (ca. 10 \u0026times; 7 \u0026times; 1 mm\u003csup\u003e3\u003c/sup\u003e). The temperature range was fixed from \u0026minus;\u0026thinsp;20 to 120\u0026deg;C with a heating rate of 2\u0026deg;C\u0026middot;min\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section3\"\u003e \u003ch2\u003e2.3.4. Thermogravimetric analysis (TGA)\u003c/h2\u003e \u003cp\u003eThermal stability and degradation profile of the prepared TPS samples were studied using, NETZSCH STA 449F3, TGA-50 from 20 to 800\u0026deg;C at 10 K‧min\u003csup\u003e\u0026ndash;1\u003c/sup\u003e rate under a nitrogen atmosphere.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section3\"\u003e \u003ch2\u003e2.3.5. Water uptake\u003c/h2\u003e \u003cp\u003eWater uptake ratio of the prepared samples was determined using the gravimetric method at an ambient temperature. The samples were cut into discs with a diameter of 2 cm and dried at 105\u0026deg;C in an oven to reach the constant weight (W\u003csub\u003ed\u003c/sub\u003e). The dried samples were then soaked in distilled water for 24 h to reach the equilibrium state. The wet weight of the swollen samples was measured after the removal of excess water from the surface of the films (W\u003csub\u003es\u003c/sub\u003e). The Water uptake ratio (WU) was calculated by the Eq.\u0026nbsp;1.\u003c/p\u003e \u003cp\u003e \u003cspan class=\"InlineEquation\"\u003e \u003cspan class=\"mathinline\"\u003e\\(WU \\left(\\%\\right)=\\frac{{W}_{s}-{W}_{d}}{{W}_{d}}\\times 100\\)\u003c/span\u003e \u003c/span\u003e (Eq.\u0026nbsp;1)\u003c/p\u003e \u003cp\u003ewhere \u003cem\u003eW\u003c/em\u003e\u003csub\u003es\u003c/sub\u003e and \u003cem\u003eW\u003c/em\u003e\u003csub\u003ed\u003c/sub\u003e are the weight of the swollen and dried samples, respectively.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section3\"\u003e \u003ch2\u003e2.3.6. Weight loss in water\u003c/h2\u003e \u003cp\u003eThe specimens of each sample were measured with the dimension of 2 \u0026times; 2 cm (W\u003csub\u003e1\u003c/sub\u003e) and dried at 105\u0026deg;C for 5 h and weighed again (W\u003csub\u003e2\u003c/sub\u003e). Then, triplicate specimens of each TPS sample were immersed in deionized water and maintained at ambient conditions for 24 h. After filtering out, the insoluble portion was dried in an oven at 60\u0026deg;C for 24 h and weighed (W\u003csub\u003e3\u003c/sub\u003e). The moisture content (MC) and percentage of the weight loss in water (W\u003csub\u003eL\u003c/sub\u003e) were calculated according to equations 2 and 3, respectively.\u003c/p\u003e \u003cp\u003e \u003cspan class=\"InlineEquation\"\u003e \u003cspan class=\"mathinline\"\u003e\\(MC \\left(\\text{\\%}\\right)=\\frac{{W}_{1}- {W}_{2} }{{W}_{2}}\\times 100\\)\u003c/span\u003e \u003c/span\u003e (Eq.\u0026nbsp;2)\u003c/p\u003e \u003cp\u003e \u003cspan class=\"InlineEquation\"\u003e \u003cspan class=\"mathinline\"\u003e\\({W}_{\\text{L}} \\left(\\text{\\%}\\right)=\\left(\\frac{{W}_{2}- {W}_{3} }{{W}_{2}}\\right)\\times 100\\)\u003c/span\u003e \u003c/span\u003e (Eq.\u0026nbsp;3)\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section3\"\u003e \u003ch2\u003e2.3.7. In vitro release of vitamin B\u003csub\u003e2\u003c/sub\u003e\u003c/h2\u003e \u003cp\u003eIn vitro vitamin release from the prepared films was studied in phosphate buffer (PBS) solution (pH 7.4). Briefly, 200 mg of the vitamin B\u003csub\u003e2\u003c/sub\u003e-loaded TPS without and with different contents of BC were suspended into the vials containing 20 mL of PBS, separately. At regular time intervals, 3 mL of the solution was taken and its absorbance was recorded at 446 nm using a UV-Vis spectrophotometer (Cary 50 UV-Vis spectrophotometer, Varian, Australia). The fresh solvent with the same volume was immediately injected into the harvested vials. The cumulative release of the vitamins from the prepared films was calculated by Eq.\u0026nbsp;4.\u003c/p\u003e \u003cp\u003e \u003cspan class=\"InlineEquation\"\u003e \u003cspan class=\"mathinline\"\u003e\\(\\text{c}\\text{u}\\text{m}\\text{u}\\text{l}\\text{a}\\text{t}\\text{i}\\text{v}\\text{e} \\text{r}\\text{e}\\text{l}\\text{e}\\text{a}\\text{s}\\text{e} \\left(\\text{\\%}\\right)=\\frac{{M}_{t}}{{M}_{0}}\\times 100\\)\u003c/span\u003e \u003c/span\u003e (Eq.\u0026nbsp;4)\u003c/p\u003e \u003cp\u003ewhere \u003cem\u003eM\u003c/em\u003e\u003csub\u003et\u003c/sub\u003e is the amount of released VB from the TPS at time t and \u003cem\u003eM\u003c/em\u003e\u003csub\u003e0\u003c/sub\u003e is the amount of VB in the TPS samples. The experiments were performed in triplicate, and the results were recorded as an average with an error bar that represents the relative standard deviation.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"3. Results And Discussion","content":"\u003cp\u003eIn short, in this study, thermoplastic films were synthesized based on starch biopolymer. Bentonite clay was added as reinforcement to improve the physic-chemical characteristics of the TPS. This casted film was fortified by VB. The individual and simultaneous effects of BC and VB were studied on the tensile strength of nanocomposites. Thermal stability and degradation profiles of the prepared nanocomposites were studied by TGA. The swelling degree and weight loss of the synthesized nanocomposites were investigated after individual/or simultaneous incorporation of BC and VB. Finally, the release profile of VB was evaluated from the nanocomposite containing various amounts of BC.\u003c/p\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003e3.1. CHN elemental analysis\u003c/h2\u003e \u003cp\u003eCHN analysis was performed to confirm the presence of VB in TPS/BC nanocomposites. Carbon, hydrogen, and nitrogen contents of the TPS, TPS/BC, TPS/VB, and TPS/BC/VB were measured by CHN elemental analysis, and the results are summarized in Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e. The results show the presence of nitrogen atoms in the TPS/VB10 and TPS/BC10/VB10 samples, while the nitrogen in TPS and TPS/BC10 are equal to zero. This confirms the presence of VB in the VB-fortified samples.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\u003cdiv class=\"gridtable\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"±\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"±\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eCHN elemental analysis results of the TPS samples containing bentonite clay (BC) and vitamin B\u003csub\u003e2\u003c/sub\u003e (VB).\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSample\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eC\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eN\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eH\u003c/p\u003e \u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c2\"\u003e \u003cp\u003e39.41 ± 0.20\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c4\"\u003e \u003cp\u003e7.0 ± 0.2\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/BC10\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c2\"\u003e \u003cp\u003e37.33 ± 0.13\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c4\"\u003e \u003cp\u003e6.7 ± 0.1\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/VB10\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c2\"\u003e \u003cp\u003e40.69 ± 0.17\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e1.10 ± 0.03\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c4\"\u003e \u003cp\u003e6.81 ± 0.04\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/BC10/VB10\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c2\"\u003e \u003cp\u003e38.15 ± 0.21\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.99 ± 0.1\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c4\"\u003e \u003cp\u003e6.69 ± 0.15\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e \u003cp\u003e\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec15\" class=\"Section2\"\u003e \u003ch2\u003e3.2. Mechanical properties\u003c/h2\u003e \u003cp\u003eThe values of mechanical properties, including tensile stress, elongation at the break, and Young’s modulus are summarized in Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. Moreover, Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e represents the dependence of BC and VB contents on the ultimate tensile strength and strain at break of the TPS nanocomposite films. Considering the effect of BC, it is seen that the tensile strength and Young’s modulus of the TPS nanocomposite film increase slightly with rising content of BC compared to the neat TPS film. Moreover, the incorporation of BC leads to the increase in the resistance of the nanocomposite film to elongation. This observation is due to the strong interaction between starch and BC, which limits the interactions of water and glycerol to interact with starch. Therefore, in contrast to glycerol (as a plasticizer), BC plays an anti-plasticization role. These findings were consistent with the previous published data [\u003cspan additionalcitationids=\"CR33 CR34\" citationid=\"CR32\" class=\"CitationRef\"\u003e32\u003c/span\u003e–\u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e35\u003c/span\u003e]. The dispersion of clay nanolayers in the TPS matrix may optimize the number of available reinforcing elements to carry the applied load and deflecting cracks, resulting in such mechanical strength increase [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e36\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\u003cdiv class=\"gridtable\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"±\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"±\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\"±\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eMechanical properties, including tensile strength, elongation at break, and Young’s modulus of the TPS nanocomposites. The concentration is shown in php as the number after each code.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e\u003ccolgroup cols=\"4\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSample Code\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTensile Strength\u003c/p\u003e \u003cp\u003e(MPa)\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eElongation at Break\u003c/p\u003e \u003cp\u003e(%)\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eYoung’s Modulus (MPa)\u003c/p\u003e \u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c2\"\u003e \u003cp\u003e5.4 ± 0.7\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c3\"\u003e \u003cp\u003e73.8 ± 11.9\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c4\"\u003e \u003cp\u003e51.2 ± 23.7\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/BC3\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c2\"\u003e \u003cp\u003e5.5 ± 0.2\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c3\"\u003e \u003cp\u003e72.7 ± 4.6\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c4\"\u003e \u003cp\u003e47.7 ± 2.8\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/BC10\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c2\"\u003e \u003cp\u003e6.3 ± 0.7\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c3\"\u003e \u003cp\u003e49.7 ± 7.0\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c4\"\u003e \u003cp\u003e138.7 ± 60.4\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/VB1\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c2\"\u003e \u003cp\u003e4.9 ± 0.4\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c3\"\u003e \u003cp\u003e89.5 ± 13.8\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c4\"\u003e \u003cp\u003e50.0 ± 13.9\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/VB5\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c2\"\u003e \u003cp\u003e3.8 ± 1.0\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c3\"\u003e \u003cp\u003e57.5 ± 11.8\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c4\"\u003e \u003cp\u003e37.3 ± 8.4\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/VB10\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c2\"\u003e \u003cp\u003e3.4 ± 0.7\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c3\"\u003e \u003cp\u003e41.4 ± 7.4\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c4\"\u003e \u003cp\u003e28.4 ± 1.8\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/BC3/VB1\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c2\"\u003e \u003cp\u003e5.7 ± 0.3\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c3\"\u003e \u003cp\u003e81.1 ± 5.8\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c4\"\u003e \u003cp\u003e54.1 ± 5.2\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/BC3/VB5\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c2\"\u003e \u003cp\u003e7.6 ± 1.4\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c3\"\u003e \u003cp\u003e62.4 ± 12.1\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c4\"\u003e \u003cp\u003e205.6 ± 46.1\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/BC3/VB10\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c2\"\u003e \u003cp\u003e5.4 ± 0.5\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c3\"\u003e \u003cp\u003e71.1 ± 2.5\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c4\"\u003e \u003cp\u003e88.5 ± 26.1\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/BC10/VB1\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c2\"\u003e \u003cp\u003e6.6 ± 1.4\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c3\"\u003e \u003cp\u003e43.7 ± 9.1\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c4\"\u003e \u003cp\u003e159.9 ± 72.6\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/BC10/VB5\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c2\"\u003e \u003cp\u003e8.0 ± 2.3\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c3\"\u003e \u003cp\u003e39.3 ± 8.6\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c4\"\u003e \u003cp\u003e246.2 ± 73.4\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/BC10/VB10\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c2\"\u003e \u003cp\u003e7.0 ± 0.2\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c3\"\u003e \u003cp\u003e47.9 ± 3.5\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\"±\" colname=\"c4\"\u003e \u003cp\u003e169.6 ± 22.7\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e \u003cp\u003e\u003c/p\u003e \u003cp\u003eThe corresponding results of mechanical properties for the TPS films containing vitamin B\u003csub\u003e2\u003c/sub\u003e can be seen in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e and Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. These results exhibit a decrease in tensile strength and Young’s modulus for the materials with various amounts of vitamin B\u003csub\u003e2\u003c/sub\u003e compared to the neat TPS film. This behavior indicates the presence of more hydrophilic groups in the samples as a function of higher content of VB. According to the literature [\u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e37\u003c/span\u003e, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e], more absorbed humidity can act as an additional plasticizer. Herein, the lower tensile strength of the vitamin-fortified TPS (TPS-VB1, TPS-VB5, and TPS-VB10) films with the higher vitamin B\u003csub\u003e2\u003c/sub\u003e content can be attributed to the existence of more pores in the TPS matrix.\u003c/p\u003e \u003cp\u003eHowever, it was observed that the incorporation of BC into the TPS/VB film led to a substantial increase in tensile strength and Young’s modulus. The explanation of this phenomenon may consist of two performances of silicate layers, including the reinforcing effect of clay particles and blocking of the pores created by the addition of vitamin B\u003csub\u003e2\u003c/sub\u003e. The most important role of vitamin concentration was demonstrated in the mechanical properties by the values of tensile strength for 5 php VB. This increase may have been facilitated by interactions among starch chain, clay particles and VB, in which many factors, including the ratio of amylose-amylopectin in starch, dispersion and exfoliation of BC, and the amount of VB can play a critical role [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. It is well-known that plasticizers are also essential additives since they can improve the flexibility and handling of films, maintain integrity, and avoid pores and cracks in the polymeric matrix [\u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e39\u003c/span\u003e, \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e40\u003c/span\u003e]. From this point of view, the action of VB as a plasticizer for starch molecules should be considered as another factor to explain this result. Consequently, use of an optimum amount of VB and BC can cause synergistic effects on mechanical properties. This explanation is supported by the shape of the stress–strain curves for the TPS nanocomposites displayed in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003e3.3. Dynamic mechanical thermal analysis (DMTA)\u003c/h2\u003e \u003cp\u003eThe mechanical response of the sample under a small harmonic force was recorded in DMTA measurements. Also, the viscoelastic response of polymers, which is associated with the molecular motions related to internal changes of the polymers, was evaluated by this technique. Relaxation processes undergoing in the studied samples during gradual heating can be detected through inflection points in storage modulus as well as maxima in both the loss modulus and the damping factor temperature dependences as some deal of received energy dissipates through viscous movement [\u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e41\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe storage modulus obtained from the DMTA analysis of the TPS nanocomposite films are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e. The storage modulus (G\u003csup\u003eʹ\u003c/sup\u003e) of samples containing BC and VB was higher than the neat TPS film. It has been known that the storage modulus was associated with stiffness, which was affected by the glass transition temperature (\u003cem\u003eT\u003c/em\u003e\u003csub\u003eg\u003c/sub\u003e), morphology, and structure of the polymer matrix. This observation may be related to the interactions among starch chain, clay particles, and VB, which was indicated by the mechanical properties (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eFigure \u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e represents the tan δ curves as a function of temperature. Tan δ is the viscoelasticity index of the material, which is usually defined as a damping term. The temperatures of the appearance of maximum tan δ determined from data in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, are displayed in Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e. Theoretically, in tan δ temperature dependences of TPS with higher plasticizer contents, two relaxation peaks usually appear which reflected the partial miscibility of starch and glycerol. The first one close to the glass transition temperature of the plasticizer is related to the glycerol-rich domains, in which the mobility of starch chains is controlled by glycerol molecules motion. The second relaxation temperature corresponds to the starch-rich domains [\u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e38\u003c/span\u003e, \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e42\u003c/span\u003e]. As seen in Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, the main relaxation of the starch-rich phase shifted to the higher temperatures with rising vitamin B\u003csub\u003e2\u003c/sub\u003e content for TPS/BC/VB nanocomposites. This observation can be explained by the interaction among the starch, glycerol, BC, and VB, thus restricting the mobility of the starch chains. Therefore, the macromolecules are restricted in motion so that their segmental relaxation is observed at higher temperatures [\u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e43\u003c/span\u003e, \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e44\u003c/span\u003e]. Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e shows that the relaxation temperature for TPS/VB samples increased, reaching a maximum for TPS/VB5 sample, then slightly decreased for TPS/VB10. This trend can be attributed to the existence of high amounts of hydrophilic groups in the TPS/VB10 sample.\u003c/p\u003e \u003cp\u003eInterestingly, in the case of TPS nanocomposite containing 5 php of VB, a broad relaxation peak was observedwith a higher intensity compared to the other samples, indicating strong interaction among the components. These results were also supported by a substantial increase in both tensile strength and Young’s modulus.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\u003cdiv class=\"gridtable\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eTemperatures of the appearance of maximum tan δ determined from data in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e\u003ccolgroup cols=\"2\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSample code\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003epeak T (°C)\u003c/p\u003e \u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e19.3\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/VB1\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e19.2\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/VB5\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e24.6\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/VB10\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e23.2\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/BC3\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e13.6\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/BC3/VB1\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e13.6\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/BC3/VB5\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e14.2\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/BC3/VB10\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e16.9\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/BC10\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e19.3\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/BC10/VB1\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e14.0\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/BC10/VB5\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e15.3\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/BC10/VB10\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e17.0\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e \u003cp\u003e\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec17\" class=\"Section2\"\u003e \u003ch2\u003e3.4. Thermogravimetric analysis\u003c/h2\u003e \u003cp\u003eThermal stability and degradation profile of the prepared samples were evaluated by TGA. Figure\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e shows the thermal behavior of bentonite-reinforced nanocomposites containing vitamin B\u003csub\u003e2\u003c/sub\u003e. The initial weight loss observed in the temperature range of 20–200°C is attributed to the elimination of unbonded and bonded water molecules [\u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e45\u003c/span\u003e]. Two distinct stages of mass loss from 220–350°C correspond to the degradation of starch and vitamin B\u003csub\u003e2\u003c/sub\u003e, verifying the compatibility of vitamin with starch. Starch was found to degrade between 300–500°C [\u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e46\u003c/span\u003e]. It was reported that vitamin B\u003csub\u003e2\u003c/sub\u003e firstly decomposed at ribo block by losing three molecules of water resulting in the formation of alcohol, ethylene, and acetaldehyde. The second weight loss for vitamin B\u003csub\u003e2\u003c/sub\u003e at a temperature over 250°C is attributed to the degradation of flavin block which leads to the formation of CO\u003csub\u003e2\u003c/sub\u003e, phenol, and char [\u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e47\u003c/span\u003e, \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e48\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe temperatures corresponding to the weight losses of 10%, 50%, 70%, and 90% are presented in Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e. The onset of decomposition for TPS/BC3/VB5, TPS/BC3/VB10, TPS/BC10/VB1, TPS/BC10/VB5, and TPS/BC10/VB10 is occurred at around 230, 232, 245, 234, and 238°C, respectively. As proved in thermal patterns, increase of the amount of bentonite from 3 php to 10 php resulted in increase of the thermal stability of nanocomposites. These findings are in agreement with the previous reports on improving the thermal resistance of nanocomposites in the presence of bentonite [\u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e49\u003c/span\u003e, \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e50\u003c/span\u003e] or MMT [\u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e51\u003c/span\u003e, \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e52\u003c/span\u003e]. Clay-reinforced nanocomposites were found to form char with a multilayered carbonaceous silicate structure during pyrolysis. This leads to preserving its structure in the polymer matrix at temperatures over 500°C. The carbonaceous-silicate char formed on the film’s surface acts as an insulator and delays the release of components produced during decomposition [\u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e53\u003c/span\u003e]. As revealed in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e, inorganic residue increased for the nanocomposites containing 10 php BC compared to those containing 3 php BC. This increment at around 800°C further approves the successful incorporation of BC into the starch matrix.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e\u003cdiv class=\"gridtable\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eTemperatures corresponded to weight losses of 10%, 50%, 70%, and 90%\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e\u003ccolgroup cols=\"5\"\u003e\u003c/colgroup\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eSample\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colspan=\"4\" nameend=\"c5\" namest=\"c2\"\u003e \u003cp\u003eT (°C)\u003c/p\u003e \u003c/th\u003e\u003c/tr\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10%\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e50%\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e70%\u003c/p\u003e \u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e90%\u003c/p\u003e \u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/BC3/VB5\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e230.3\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e307.1\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e324.3\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e917.5\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/BC3/VB10\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e233.0\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e307.1\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e324.4\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e912.2\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/BC10/VB1\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e245.0\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e313.0\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e332.0\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e956.0\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/BC10/VB5\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e232.8\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e312.3\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e326.0\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e943.4\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTPS/BC10/VB10\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e238.3\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e312.4\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e329.5\u003c/p\u003e \u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e948.4\u003c/p\u003e \u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/table\u003e\u003c/div\u003e \u003cp\u003e\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec18\" class=\"Section2\"\u003e \u003ch2\u003e3.5. Swelling behaviors and weight loss\u003c/h2\u003e \u003cp\u003eThe effect of BC and VB was studied on the swelling behavior of TPS and the results are presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e. As shown, the swelling ratio of TPS film decreased by incorporating 3 php of BC. This finding may be ascribed to the interaction between BC and the polymer, which prevents water diffusion into the nanocomposite. In contrast, the swelling ratio of TPS film increased with the addition of 10 php BC (TPS/BC10). It was reported that the interaction between starch and BC increased the surface hydrophilicity facilitating the diffusion of water molecules [\u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e54\u003c/span\u003e]. This behavior may be concluded from the increased porosity of the composites. Moreover, the high specific surface area of the nanoplatelets of bentonite, provides the perfect contact with starch which leads to a reduction in the permeability of the composites [\u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e55\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe swelling ratio for TPS films reinforced with 1 php and 5 php of vitamin B\u003csub\u003e2\u003c/sub\u003e showed an increase compared to TPS film. This result can be attributed to the higher affinity of vitamin B\u003csub\u003e2\u003c/sub\u003e to absorb water, which enhances the hydrophilicity of vitamin-reinforced TPS composite. This finding is consistent with the published data on the increase of the swelling degree of riboflavin-loaded chitosan [\u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e56\u003c/span\u003e]. Whereas, further increase of vitamin B\u003csub\u003e2\u003c/sub\u003e (10 php) caused a decrease in the swelling ratio. The reason for the decrease may consist in the effective reactions between functional groups of starch and vitamin, which formed a more compact structure, limiting the penetration of water molecules into the matrix [\u003cspan citationid=\"CR57\" class=\"CitationRef\"\u003e57\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eSince solubility is determined as the main criterion for measuring the water resistance of the prepared films, the degradation behavior of TPS-based nanocomposites was studied by measuring their solubility after regular incubation times (10, 24, and 48 hours) in PBS (pH 7.4) at 37°C. As shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e, the weight loss for all of the prepared samples increased with increasing incubation time. It was also revealed that the addition of both BC and VB in TPS films influenced the degradation rate of the nanocomposite. The incorporation of BC into TPS film significantly decreased the solubility of the nanocomposite, which could hinder the water penetration into the matrix. This result may occur due to the formation of strong hydrogen bonds between hydroxyl groups of BC and the hydroxyl groups of starch, which may increase the cohesiveness of the nanocomposite matrix and decrease their water sensitivity [\u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e58\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec19\" class=\"Section2\"\u003e \u003ch2\u003e3.6. Release profile of vitamin B\u003csub\u003e2\u003c/sub\u003e from nanocomposite\u003c/h2\u003e \u003cp\u003eThe release profiles of VB from the prepared nanocomposites during 96 h are presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e. At a glance, Fig.\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e shows that the release of VB from nanocomposites depends on the content of BC, the higher BC content, the slower VB release. The released VB from TPS/VB1 was 52%, which decreased to 42% and 27% in the presence of 3 and 10 php BC, respectively. On the other hand, around 80% of VB was released from TPS/VB5, while the release content reached 64% and 52% after incorporating 3 and 10 php BC, respectively. The incorporation of 3 and 10 php of BC into TPS/VB10 resulted in decrease of the vitamin release from 60–50% and 46%, respectively. It is also clear that more sustained VB release was attained in BC-reinforced TPS/VB. This behavior might be ascribed to the barrier properties of the clay, which hinders the fast penetration of hydrophilic VB into aqueous media by creating a tortious path, as described by the effect of clay on the release of VB and various drugs in the literature [\u003cspan additionalcitationids=\"CR60 CR61\" citationid=\"CR59\" class=\"CitationRef\"\u003e59\u003c/span\u003e–\u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e62\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Conclusions","content":"\u003cp\u003eThis work provided new insights into developing thermoplastic starch/bentonite clay (TPS/BC) nanocomposite fortified with vitamin B\u003csub\u003e2\u003c/sub\u003e (VB) toward understanding a correlation between the starch/bentonite clay and VB. Therefore, the effect of VB on the physicochemical properties of TPS/bentonite clay nanocomposite films as well as the vitamin release behavior were evaluated. Incorporating higher amounts of BC and VB into the TPS matrix results in a substantial increase in tensile strength and Young’s modulus, while decreasing the corresponding elongation at break. This phenomenon indicates the reinforcing effect of clay particles and blocking the pores created by addition of VB, which could show synergetic impact at a specific concentration of BC and VB. The nanocomposites containing 5 parts based on the dry weight of starch (php) VB e.g., TPS/BC3/VB5 and TPS/BC10/VB5 exhibited the highest increase in tensile strength and Young’s modulus. Moreover, the nanocomposites demonstrated an increase in the main relaxation of the starch-rich phase with the rising VB content, as revealed by the dynamic mechanical thermal analysis (DMTA) results, confirming the restriction of the mobility of the starch chains. The TPS nanocomposites reinforced with 1 php and 5 php VB showed an increase in water uptake compared to the TPS film, which is attributed to the higher affinity of VB to absorb water due to enhanced hydrophilicity of vitamin-reinforced TPS composite. The release studies indicate that the TPS nanocomposites with a higher BC content resulted in a lower amount and delayed vitamin release, indicating good potential for vitamin delivery purposes.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgment\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors express their gratitude to the Endocrinology and Metabolism Research Center of Kerman University of Medical Sciences and Shahid Bahonar University of Kerman. This work was also supported by the Slovak Research and Development Agency under the contract number APVV-18-0480 and VEGA Grant Agency under contract number 2/0121/23. This work is the result of the project implementation CEMBAM \u0026ndash; Centre for Medical Bio-Additive Manufacturing and Research, ITMS2014+: 313011V358 and Advanced bioactive hydrogel scaffolds for regenerative medicine (ABSACARM), ITMS2014+: 313011BWL6 supported by the Operational Programme Integrated Infrastructure funded by the European Regional Development Fund.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eH. Peidayesh, A. Heydari, K. Mosnackova, I. Chodak, In situ dual crosslinking strategy to improve the physico-chemical properties of thermoplastic starch, Carbohydr Polym 269 (2021) 118250.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eH. Peidayesh, Z. Ahmadi, H.A. Khonakdar, M. Abdouss, I. Chodak, Baked hydrogel from corn starch and chitosan blends cross-linked by citric acid: Preparation and properties, Polym Adv Technol 31(6) (2020) 1256\u0026ndash;1269.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eF. Ivanic, D. Jochec-Moskova, I. Janigova, I. Chodak, Physical properties of starch plasticized by a mixture of plasticizers, Eur Polym J 93 (2017) 843\u0026ndash;849.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eS.M. Amaraweera, C. Gunathilake, O.H.P. Gunawardene, N.M.L. Fernando, D.B. Wanninayaka, R.S. Dassanayake, S.M. Rajapaksha, A. Manamperi, C.A.N. Fernando, A.K. Kulatunga, A. Manipura, Development of Starch-Based Materials Using Current Modification Techniques and Their Applications: A Review, Molecules 26(22) (2021) 6880.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eM. Xiaofei, Y. Jiugao, F. 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Erim, Natural alginate biopolymer montmorillonite clay composites for vitamin B2 delivery, J Bioact Compat Pol 30(1) (2015) 48\u0026ndash;56.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eR. Garcia-Vazquez, E.P. Rebitski, L. Viejo, C. de los Rios, M. Darder, E.M. Garcia-Frutos, Clay-based hybrids for controlled release of 7-azaindole derivatives as neuroprotective drugs in the treatment of Alzheimer's disease, Appl Clay Sci 189 (2020) 105541.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Thermoplastic starch, Vitamin B2, Active packaging","lastPublishedDoi":"10.21203/rs.3.rs-2587534/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-2587534/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThermoplastic starch (TPS) attracted great interest in the biopolymer industry due to its obvious advantages, such as biodegradability and renewable resources, as substitutes for petroleum-based materials. This study is focused on designing TPS/bentonite clay (BC) nanocomposite (TPS/BC) reinforced with vitamin B\u003csub\u003e2\u003c/sub\u003e (VB). The TPS nanocomposites loaded with various contents of BC were prepared using regular cornstarch/clay plasticized with glycerol. Subsequently, the various content of VB was encapsulated into TPS/BC. The effects of VB were investigated on the physicochemical properties of the TPS/BC films including mechanical and thermal properties, water uptake, and weight loss in water. The tensile strength and Young\u0026rsquo;s modulus of TPS/BC/VB films were found to increase significantly with adding and rising the VB content. The highest tensile and Young\u0026rsquo;s modulus values were observed for the nanocomposites containing 5 php of VB and 3 php of BC which indicates their synergistic effects on the mechanical properties of TPS. TPS reinforced with 1 php and 5 php VB showed an increase in water uptake compared to the TPS. The release of VB was evaluated from the nanocomposite films. Our findings show that higher BC content leads to lower VB release, which indicates the control of VB release by BC content.\u003c/p\u003e","manuscriptTitle":"Thermoplastic starch/bentonite clay nanocomposite reinforced with vitamin B2: Physicochemical characteristics and release behavior","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2023-02-17 14:34:53","doi":"10.21203/rs.3.rs-2587534/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"dce06939-5add-4edd-acda-7990d4089697","owner":[],"postedDate":"February 17th, 2023","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2023-02-17T14:34:53+00:00","versionOfRecord":[],"versionCreatedAt":"2023-02-17 14:34:53","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-2587534","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-2587534","identity":"rs-2587534","version":["v1"]},"buildId":"7rjqhiLT3MXkJMwkYKINL","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}