Preparation of epoxy-functionalized AES (GAES) resins by high-temperature bulk polymerization

Preparation of epoxy-functionalized AES (GAES) resins by high-temperature bulk polymerization | 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 Preparation of epoxy-functionalized AES (GAES) resins by high-temperature bulk polymerization Liting Sun, Mingdong Li, Bing Nie, Jianying Ma, Chunlei Cao This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4204404/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 12 Sep, 2024 Read the published version in Journal of Polymer Research → Version 1 posted 5 You are reading this latest preprint version Abstract In this paper, the monomers of styrene (St), acrylonitrile (AN), and glycidyl methacrylate (GMA) were grafted onto ethylene-propylene-diene-monomer (EPDM) rubbers, and the epoxy-functionalized AES (GAES) resins were successfully prepared by high-temperature bulk polymerization. The effects of polymerization reaction conditions, i.e. the content of initiator and chain transfer agent, the content of EPDM and GMA on the grafting rate, composition of free copolymers, molecular weights and their distributions of GAES resins were investigated in detail. The influence of GMA content on the thermal stabilities of GAES resins were also discussed. Experimental results showed that under the optimized experimental conditions, the highest grafting rate of GAES resins reached to 48.8% and the grafting efficiency was 35.3%. Under the same reaction conditions, the molecular weights of free copolymers can reach to 70,000 g mol − 1 . The content of initiator and chain transfer agent had no obvious influence on the composition of free copolymers, but the component of GMA in free copolymers increased gradually with increasing content of EPDM. TG analysis results indicated that the incorporation of GMA decreased the thermal stabilities of GAES resins. Epoxy-functionalized AES resins Grafting rate Molecular weights Free copolymers Thermal stability Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Introduction Polyester materials such as polycarbonate (PC) [ 1 – 3 ], poly(butylene terephthalate) (PBT) [ 4 , 5 ] and polyamide 6 (PA6) [ 6 ], as high-performance engineering plastics, play an important role in agriculture, industry and food packaging because of their good processability and mechanical properties. However, the inherent high notch sensitivity of polyester materials impose limitations on their suitability for certain applications in some fields [ 7 ]. Therefore, it is imperative to enhance the toughness of polyester materials. Currently, the most cost-effective and efficient approach involves physical blending with toughening agents to fabricate polymer composites. The following four kinds of toughening agents are usually applied in physical blending: rubbers, thermoplastic elastomers, traditional petroleum-based plastics, and inorganic nanoparticles [ 8 – 10 ]. Inorganic nanoparticles are frequently compounded with rubbers or thermoplastic elastomers to achieve the effect of synergistic toughening. Thermoplastic elastomers exhibit superior toughening performance compared to other types of toughening agents due to the unique structure containing both plastic (hard) and rubber (soft) segments [ 11 ]. Among them, ABS resins with core-shell structure have been extensively investigated for their potential in enhancing the toughness of polyester [ 5 , 12 ]. Theoretically, the use of physical blending method can effectively enhance the polymer’s toughness. However, the toughening effect is usually unsatisfactory because of the poor compatibility between polymers and toughening agent [ 13 , 14 ]. Therefore, the compatibilizers are necessary and often added to enhance the compatibility of two phases during the process of physical blending, thus improving the overall performance of composites [ 15 , 16 ]. Alternatively, the toughening agents can be modified by incorporating some monomers with high reactivity [ 17 ]. Then the modified toughening agents reacted with toughened polymers, and promoted the formation of block or graft copolymers, thereby enhancing the compatibility of two phases [ 5 ]. Functionalization of toughening agent improve the toughening effect compared to the previous method [ 18 , 19 ]. At present, the functional monomers, such as acrylic acid (AA), maleic anhydride (MAH) [ 20 ], glycidyl methacrylate (GMA) [ 21 , 22 ], were often used most in the studies of functionalization of ABS resins [ 23 ]. During the process of melt blending, the reactive groups can react with the inherent groups of polyesters to form block or graft copolymers in situ at interface of two phases, which improve the compatibility of two phases [ 24 ]. The current research primarily employ the melt extrusion or emulsion polymerization methods. Nevertheless, the grafting rate achieved through melt extrusion is relatively lower and fails to obtain significant enhancement effects. The emulsion polymerization can obtain a higher grafting rate, but its implementation on a large scale is hindered by the complexity of the subsequent processing steps. In addition, due to the high processing temperature of PC, PBT, PA6 and other polymers, the long-term high temperature will lead to oxidative degradation of the unsaturated double bond in ABS resins and reduce the toughening effect, which will result in decline of overall performance of composites [ 25 ]. The researches show that the use of saturated rubbers instead of polybutadiene rubbers in ABS resins is a good solution to this problem [ 26 ]. Among them, the use of EPDM rubbers in AES resins which not only prevent polymers from oxidative degradation at high processing temperatures, but also endow polymers with better weather resistance. Therefore, the aim of our paper is to synthesize epoxy-functionalized AES resins (GAES resins) by high-temperature bulk polymerization, and functional monomers (GMA) were introduced in the synthesis of GAES resins. The method is characterized and proved by the fact that when the products are used as toughening agent, there is no need to add compatibilizer, and the products can form block or graft copolymers with polyesters in situ to improve the compatibility of two phases. The products synthesized by high-temperature bulk polymerization usually have special morphologies, such as internal inclusion structure, salami structure, and the existence of these structures can effectively improve the toughening effect. In addition, the products obtained by high-temperature bulk polymerization usually possess the following advantage when compared with emulsion polymerization and solution polymerization: purity of products, continuous production, short experimental period, and less pollution to environment [ 27 ]. When AXS resins are used as toughening agents to toughen polyesters, the grafting rate of resins [ 28 , 29 ], molecular weights and distributions of free copolymers, and phase morphologies are important factors to determine toughening effect [ 30 , 31 ]. Therefore, this paper focuses on the effects of polymerization conditions, i.e. content of initiator and chain transfer agent, content of EPDM and TDM, on graft copolymerization reaction of GAES resins and compositions, molecular weights and distributions of free copolymers. Meanwhile, the effect of GMA content on thermal stability of GAES resins were also discussed. Experimental Materials Acrylonitrile and ethylbenzene (industrial grade, Petro China Jilin Petrochemical Company, China) were purified by means of distillation. Styrene (industrial grade, Petro China Fushun Petrochemical Company, China) was washed with 5% aqueous sodium hydroxide, subsequently washed with water to neutral, dried with anhydrous sodium sulfate, and finally distilled under vacuum. Glycidyl methacrylate (industrial grade, Nanjing Rongxin Chemical Technology Co., Ltd, China) was purified by means of distillation. EPDM (industrial grade, Petro China Jilin Petrochemical Company, China) was dried at 60 o C for 12 hours in vacuum. Di-tert-butyl peroxide (DTBP) and tert-dodecyl mercaptan (TDM) (chemical pure, Sinopharm Chemical Reagent Co., Ltd., China) were used directly. Synthesis of GAES resin GAES resins were prepared using high-temperature bulk polymerization, and the experimental formulations were shown in Table 1 . The preparation process was carried out according to the following steps: solvent and monomers (acrylonitrile, styrene and glycidyl methacrylate) were added into the reactor and a certain amount of EPDM was added under low-speed stirring conditions, where the mass ratio of St to AN was 3:1. Nitrogen was used to exhaust the air in the kettle, and pre-swelling was carried out under high-speed stirring conditions to ensure the rubbers were fully dissolved. Subsequently, a certain content of DTBP, TDM and a small amount of solvent were pumped into reaction kettle under a certain pressure of nitrogen, and the reaction temperature was raised to set temperature 130 o C which was chosen as reaction temperature in this paper due to the half-life of DTBP at 130 o C of 0.15 h. A small amount of resins was removed from the discharge port of reactor every ten minutes for measurement of conversion rate. The reaction was terminated when the conversion rate reached 80%. The polymerization products were finally subjected to devolatilization. Table 1 Formulas of synthesis of GAES resins experiment Temperature ( o C) initiator (wt%) chain transfer agent (wt%) rubber (wt%) GMA (wt%) a. 130 0.05 ~ 0.25 0.2 20 2 b. 130 0.1 0.05 ~ 0.25 20 2 c. 130 0.1 0.2 20 ~ 60 2 d. 130 0.1 0.2 40 2 ~ 10 Note: content of initiator and chain transfer agent were varied by 0.05 wt%, content of rubber was varied by 10 wt%, and content of GMA was varied by 2 wt%. Grafting rate The grafting rate was determined by method of high-speed centrifugation: the dried GAES resins samples (W 1 g) were added into a centrifuge tube with 20 mL of acetone, and then placed in SHA-B type water-bath thermostatic oscillator (Jiangsu Jintan Hualong Experimental Instrument Factory, China). After 12 h of dissolution by constant temperature oscillation, the centrifuge tube was transfer to GL-21M ultracentrifuge (Shanghai Institute of Centrifugal Machinery, China) and centrifuged for 30 min at 10,000 r min − 1 . After centrifugation, the upper layer clear liquid was extracted and dissolved again by acetone for three times, finally the sample after supernatant extraction was dried in vacuum to constant weight (W 2 g). The grafting rate and grafting efficiency were calculated according to the following formulas [ 32 ]: \(A=\frac{{m}_{1}}{{m}_{1}+{m}_{2}\times C}\) (2 − 1) \(GR=\frac{{W}_{2}-{W}_{1}\times A}{{W}_{1}\times A}\) (2–2) \(GE=\frac{{W}_{2}-{W}_{1}\times A}{{W}_{1}\times \left(1-A\right)}\) (2–3) A-weight ratio of rubbers in GAES resins; m 1 -mass of rubbers in the formulation (g); m 2 -mass of monomer in the formulation (g); C-monomer conversion. FTIR analysis FTIR were obtained on spectrometer measurements (Nicolet Magna-760, Nicolet Analytical Instruments, Madison, WI). The grafted copolymers and EPDM rubbers were subjected to ATR-FTIR testing using hot-pressed films. The free copolymers were tested using smear method by dipping a drop solution of this substance onto a KBr sheet and baking in an oven to remove solvent before testing. IR spectra were recorded in a wave range of 400–4000 cm − 1 . 1 H-NMR analysis 1 H-NMR spectra were acquired using a nuclear magnetic resonance superconducting instrument (Bruker Avance III 400, Bruker Company, USA). A certain amount of polymers were dissolved in CDCl 3 . The copolymer composition and structures were calculated by comparing the five proton signals at 6.5–7.5 ppm for benzene ring group of St, the proton signals at 3.61–3.81 ppm for -OCH 2 - group of GMA, and the proton signals on cyanine-adjacent carbon atoms of AN at 2.25–2.33 ppm [ 33 ]. Molecular weights of free copolymers The free copolymers were obtained by drying the supernatant after centrifugation. The samples dissolved in THF and formed a solution with concentration of 0.1%. The molecular weights of free copolymers and their distributions were measured by Waters 2414 Refractive Index Detector (DRI) with a flow rate of 1 mL min − 1 for the eluent. The linear polystyrene was used as standard sample, and the temperature was 35 o C. Thermal stability analysis Thermal decomposition behaviors were examined by mean of TG with a heating rate of 10 o C min − 1 from 30 o C to 650 o C under nitrogen atmosphere on thermogravimetric analyzer (TG209, NETZCH, Germany). Results and discussion Structure characterization of graft copolymers The structures of GAES resins components were determined by FTIR spectroscopy. As shown in Fig. 1 , the absorption peak at 2240 cm − 1 was characteristic of telescopic vibration peak of carbon nitrogen triple bond (C \(\equiv\) N). The peak at 1730 cm −1 was characteristic of telescopic vibration peak of carbonyl (C = O). The two peaks at 760 cm − 1 and 700 cm − 1 were characteristic of bending vibration peak of mono-substituted benzene ring, which were not present in the spectrum of EPDM. These results indicated that the grafting reaction had taken place and the GAES grafting copolymers were successfully prepared. Effect of polymerization conditions on grafting rate In this paper, DTBP was chosen as initiator, and the reaction was carried out in ethylbenzene. The content of EPDM, GMA and chain transfer agent was 20 wt%, 2 wt% and 0.2 wt%, respectively. The reaction temperature was kept constant at 130 o C, and the effect of initiator content on grafting reaction was discussed. The experimental results were shown in Fig. 2 , it can be seen that the grafting rate first increased and then decreased with increasing content of initiator, and reached the highest value when the initiator content was 0.2 wt%. Meanwhile, the grafting efficiency increased with increasing content of initiator. The reason for this phenomenon was that the concentration of free radicals in reaction system increased with increasing content of initiator, which was favorable for the grafting reaction [ 32 , 34 ]. However, when the initiator content exceeded 0.2 wt%, the grafting rate showed a tendency of slight decrease. We know the grafting rate is defined as the ratio of the total mass of successfully grafted monomers to the total mass of rubbers. The grafting rate mainly depended on the total mass of grafted monomers when the rubber content was fixed. Therefore, the decrease of grafting rate were related to the length of grafting chains, which were explored in detail in subsequent studies. Based on the results above, the initiator content of 0.2 wt% was chosen for subsequent experiments. The effect of chain transfer agent content on graft copolymerization were shown in Fig. 3 . TDM was chosen as chain transfer agent, and the grafting reaction was carried out in ethylbenzene. The content of EPDM, GMA and initiator 20 wt%, 2 wt% and 0.2 wt%, respectively. The reaction temperature was constant at 130 o C. As can be seen from Fig. 3 , the grafting rate of GAES resins showed an obvious decreasing trend with increasing content of chain transfer agent while the other polymerization conditions were unchanged. It was noteworthy that the more content of chain transfer agent, the slower decrease trend of grafting rate, the grafting rate was only 16.71% when the content of chain transfer agent was 0.25 wt%. The reason for the significant decrease in grafting rate can be attributed to two points: firstly, the addition of chain transfer agent reduced the probability of chain transfer of free radicals to EPDM molecular chains, which led to a decrease in the number of active centers on EPDM molecular chains, and further reduced the probability of the formation of branched chains on EPDM molecular chains. Secondly, the introduction of chain transfer agent predominantly led to termination of free copolymers chains through chain transfer to chain transfer agent, thereby significantly reducing the radical coupling termination with EPDM molecular chains and consequently diminishing branching probability via coupling termination in EPDM molecular chains. The results above indicated that the highest grafting rate was obtained when the content of initiator and chain transfer agent were 0.2 wt% and 0.1 wt%, respectively, and these two contents were chosen for the following experiments. Figure 4 revealed the effect of EPDM content on graft copolymerization. The results showed that the grafting rate first increased and then decreased with increasing content of EPDM, and reached the maximum value of 51.45% at 30 wt% content of EPDM. This change stemmed from two main sources [ 34 ]: first, the viscosity of reaction system increased with increasing content of EPDM, which limited the migration of monomer radicals to EPDM chains and made it difficult to terminate to EPDM molecular chains, finally led to decreasing of grafting rate. Second, the increase content of EPDM was equivalent to the decrease concentration of copolymerized monomers, which resulted in lower concentration of monomer radicals and reducing the probability of transfer to rubber chains, and in turn led to a rapid decrease of grafting rate. The grafting efficiency monotonically increased with increasing content of EPDM, which attributed to the fact that EPDM molecular chains provided more grafting sites at high content of EPDM, enabling more monomer radicals to successfully graft onto EPDM molecular chains. Taken together, 40 wt% content of EPDM was determined as the optimal polymerization condition in this paper. The effect of GMA content on graft copolymerization was investigated. The content of EPDM, initiator and chain transfer agent was 40 wt%, 0.2 wt% and 0.1 wt%, respectively, and the reaction temperature was130°C. The experimental results were shown in Fig. 5 , the grafting rate of GAES resins exhibited a trend of first decrease and then increase with increasing content of GMA. It was mainly because of the larger difference of polarity between GMA and AN [ 35 ], the addition of GMA had influence on the ideal copolymerization ratio of AN to St. Meanwhile, the activity of AN radicals were more higher than that of GMA radicals, and therefore the ability of capturing hydrogen from rubber chains was stronger than that of GMA radicals. The monomers were more inclined to undergo copolymerization reaction with increasing content of GMA, which affected the grafting rate and grafting efficiency of GAES resins. Effect of polymerization conditions on molecular weights and composition of free copolymers Figure 6 showed the effect of initiator content on molecular weights and their distributions of free copolymers. The molecular weights of free copolymers slowly decreased with increasing content of initiator. The reason for this phenomenon was that the increase content of initiator led to increasing concentration of monomer radicals in reaction system, which in turn led to increasing number of active centers. However, with increasing concentration of monomer radicals in reaction system, the excess radicals were not all effective for initiating polymerization reaction due to the short survival time of radicals, thus increasing the probability of termination of double radical coupling and resulting in rapid chain termination of polymers and lowering the molecular weights of copolymers. This phenomenon explained the reason for decreasing of grafting rate when the content of initiator exceeded 0.2 wt%. Meanwhile, the molecular weights distribution of free copolymers became narrower with increasing content of initiator. The effect of chain transfer agent content on molecular weights and their distributions of free copolymers were shown in Fig. 7 . The content of EPDM, GMA and initiator was 20 wt%, 2 wt% and 0.2 wt%, respectively. The reaction temperature was kept constant at 130 o C. It can be seen that chain transfer agent had a strong regulating influence on molecular weights of free copolymers, which was in line with the basic law of free radical polymerization, the molecular weights of copolymers decreased gradually with increasing content of chain transfer agent [ 36 ]. When the content of chain transfer agent was 0.1 wt%, the molecular weights of copolymers reached about 97000 g mol − 1 , and then remained basically unchanged after the content of chain transfer agent exceeded 0.15 wt%. There were two main chain transfer reactions in the reaction system: the transfer reactions to macromolecular chains and chain transfer agent. The ability of transfer to macromolecular chains was fixed because of the constant content of EPDM, the initiation efficiency of chain transfer agent was not improved with increasing content of chain transfer agent. Therefore, the molecular weights remained basically unchanged when the content of chain transfer agent exceeded 0.15 wt%. The content of chain transfer agent had slightly influence on molecular weights distribution and the PDI maintained about 1.7. The effects of EPDM content on molecular weights and their distributions of free copolymers were shown in Fig. 8 . Here the content of initiator, chain transfer agent, and GMA was 0.2 wt%, 0.1 wt% and 2 wt%, respectively. It can be seen that the content of EPDM had important influence on molecular weights of free copolymers, and the molecular weights decreased with increasing content of EPDM, especially the molecular weights decreased rapidly when the content of EPDM exceeded 40 wt%. Meanwhile, the molecular weights distributions were fluctuated around 1.6. The high content of rubbers increased the viscosity of polymerization system obviously and reduced the concentration of monomers, which resulted in decreasing of molecular weights of free copolymers. We thought the effect of EPDM content on molecular weights and molecular weights distribution mainly depended on the increasing viscosity of reaction system. when the viscosity of reaction system was higher, the effect of heat and mass transfer became more difficult, the temperature increased and the concentration distribution of reaction system became more wider, and it was easy to form gradient distribution, which finally resulted in increasing of molecular weights distribution. The relationships of GMA content and molecular weights, and their distributions of free copolymers were studied and shown in Fig. 9 . Here the content of initiator, chain transfer agent, and EPDM was 0.2 wt%, 0.1 wt% and 40 wt%, respectively. It can be seen that the molecular weights of free copolymers basically remained unchanged with increasing content of GMA, and the molecular weights decreased rapidly when the content of GMA exceeded 8 wt%. The increasing content of GMA led to a higher concentration of epoxy groups in free copolymers, thereby enhanced the site-blocking effect and impeded the attack of free radicals, ultimately resulted in decreasing of molecular weights. The molecular weights distribution decreased with increasing content of GMA and finally maintained around 1.5. The effect of polymerization conditions on the composition of free copolymers was shown in Fig. 10 . The experimental formulas were shown in Table 1 . It can be observed from Fig. 10 (a) and Fig. 10 (b) that there were little influence on the compositions of free copolymers with increasing content of initiator and chain transfer agent. For Fig. 10 (c), the component of GMA in free copolymers increased with increasing content of EPDM, but had little influence on the component of St and AN. The grafting reaction and copolymerization reaction in reaction system were the relationship of competition, the viscosity of reaction system increased with increasing content of EPDM, so that the transfer of mass and heat became more difficult, and the grafting reaction was inhibited. The larger spatial resistance of epoxy groups in GMA monomer made it difficultly move to EPDM chains, and the copolymerization reaction was more favored, which the content of GMA within free copolymers increased with increasing content of EPDM. From Fig. 10 (d), it can be found that with increasing content of GMA in free copolymers, the compositions of GMA and AN gradually increased, and the composition of St gradually decreased, which were attributed to the different polarity of these several monomers. Both GMA and AN were polar monomers, the compatibility of the two monomers was better according to the principle of similar dissolution, and St itself as a non-polar monomer was not good compatibility with the other monomers. The polarity of reaction system was gradually increased with increasing content of GMA, which led to decreasing component of St in free copolymers. Thermal stabilities of GAES resins Thermogravimetric testing of EPDM and GAES resins containing 2 wt%, 4 wt%, 6 wt%, 8 wt%, and 10 wt% (denoted as EPDM, GAES-2, GAES-4, GAES-6, GAES-8, and GAES-10, respectively) were carried out under N 2 atmosphere at a temperature increase rate of 10°C min − 1 , the TG and DTG curves were shown in Fig. 11 . The initial decomposition temperature (T in ), half weight-loss temperature (T 50% ), terminal decomposition temperature (T end ) and maximum weight-loss temperature (T max ) were characterized and compared. From Fig. 11 (a), it can be seen that the thermal degradation behaviors of GAES resins were basically similar, the T in , T 50% , T end and T max of GAES resins gradually decreased with increasing content of GMA. Table. 2 recorded the thermal degradation temperatures at each stage of thermal degradation and the maximum weight-loss temperatures of EPDM and GAES resins with different content of GMA. T in of GAES resins decreased about 12 o C when the content of GMA increased from 2 to 10 wt%. T in was used as a criterion for evaluating the thermal stabilities of polymers. The decreasing of T in indicated the incorporation of GMA monomers decreased the thermal stabilities of GAES resins, and the more content of GMA, the worse thermal stabilities of GAES resins. As can be seen from Fig. 11 (b), when the content of GMA exceeded 8 wt%, a bimodal structure with two extreme values appeared on DTG curves. It was related to the properties of GMA monomer itself, the thermal degradation process of GMA under high temperature conditions was divided into two stages. The first degradation stage was the process of removing small molecular groups, which generated gases, such as CO, CO 2 , or CH 3 . The second stage was the process of random chain breakage of the residue [ 37 – 39 ]. With increasing content of GMA in GAES resins, the number of small molecular groups which removed in first degradation stage gradually increased and the rate of weight-loss also gradually increased. Therefore, the bimodal structure gradually appeared with increasing content of GMA in DTG curves. Table 2 TG/DTG data of EPDM and GAES resins with different content of GMA sample Thermal degradation temperature of ( o C) Peak temperature ( o C) T in T 50% T end T max 1 T max 2 EPDM 427 452 494 - 452 GAES-2 377 426 477 419 - GAES-4 375 425 478 415 - GAES-6 369 423 476 413 - GAES-8 367 421 477 414 439 GAES-10 365 422 475 413 438 Note: T max1 and T max2 represented peak temperatures of low-temperature and high-temperature weight-loss peak. Conclusion GAES resins were successfully prepared and the influence of polymerization conditions on the composition, molecular weights and distributions of free copolymers were investigated in detail, the effects of GMA content on thermal stabilities of GAES resins were also explored. First, the GAES resins had the maximum grafting rate with 0.2 wt% content of initiator. The grafting rate decreased with increasing content of chain transfer agent. The grafting rate was the highest when the content of EPDM was 30 wt%. Second, the increase content of initiator and chain transfer agent, EPDM and GMA, all resulted in decreasing of molecular weights, among which the influence of EPDM was more significant. Third, the content of initiator and chain transfer agent had no significant influence on the composition of free copolymers, the GMA component of copolymers gradually increased with increasing content of EPDM. Finally, the thermal stabilities of GAES resins decreased with increasing content of GMA. Declarations Conflict of interest : The authors affirm that there are no conflicts of interest to declare in relation to the research presented in this paper. References Roberto G, Sorrentino A (1994) Polycarbonate/ABS blends: a literature review. Adv Polym Tech 13(4):249-258. https://doi.org/10.1002/adv.1994.06013 0401 Quintens D, Groeninckx G, Guest M (1990) Mechanical behavior related to the phase morphology of PC/SAN polymer blends. 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Polymer 45:5265-5277. https://doi.org/10.1016/j.polymer. 2004.05.056 Zeng ZP, Wang LS, Cai TM, Zeng XB (2004) Synthesis of high rubber styrene-EPDM-acrylonitrile graft copolymer and its toughening effect on SAN. J Appl Polym Sci 94:416-423. https://doi.org /10.1002/app.20579 Dai JQ, Wang LS, Cai TM, Zhang AQ, Zeng XB (2007) EPDM/St-an graft copolymerization reaction behavior by phase inversion emulsion and the toughness effect of EPDM-g-SAN on SAN resin. J Appl Polym Sci 107:3393-3400. https://doi.org/10.1002/app.27352 Shao HJ, Qin SH, Yu J, Guo JB (2012) Influence of grafting degree on the morphology and mechanical properties of PA6/POE-g-GMA blends. Polym-Plast Technol 51(1):28-34. https://doi. org/10.1080/03602559.2011.603781 Sun SL, Tan ZY, Zhang MY, Yang HD, Zhang HX (2006) Influence of the degree of grafting on the morphology and mechanical properties of blends of poly(butylene terephthalate) and glycidyl methacrylate grafted poly(ethyleneco-propylene) (EPR). Polym Int 55:834-842. https://doi.org/ 10.1002/pi.2009 Sun SL, Tan ZY, Zhou C, Zhang MY, ZhangHX (2007) Effect of ABS grafting degree and compatibilization on the properties of PBT/ABS blends. Polym Composite 28:484-492. https:// doi.org/10.1002/pc.20318 Fu JF, Wang LS, Zhang AQ (2008) Synthesis of EPDM-graft-methyl methacrylate and styrene and its toughening effect on MS resin. Polym Bull 60:405-416. https://doi.org/10.1007/s00289-007 -0881-7 Mai JZ, Wang LS (2014) Reaction mechanism of suspension graft copolymerization of styrene and acrylonitrile in the presence of ethylene propylene diene terpolymer. Polym Chem 5:2118-2129. https://doi.org/10.1039/c3py01053h Qu XW, Shang SR, Liu GD, Zhang LC (2002) Graft copolymerization of styrene and acrylonitrile onto EPDM. J Appl Polym Sci 86:428-32. https://doi.org/10.1002/app.10992 Liu WT, Wang LS, Cai TM, Zhang AQ, Zeng XB (2010) A study of the synthesis of EPDM-g-MAN and toughness of its blend with SAN (AEMS). J Macromol Sci B 49:2319-2334. https://doi.org/10.1080/00222340903355685 Severhi F, QuattronG, Gall R (1984) Chain transfer reactions for styrene free radical polymeriz -ation in presence of mixed ethylbenzene and EPDM eubber. Die Angew Makromol Chem 127:1-6. https://doi.org/10.1002/apmc.1984.051270101 Zuifiqa M, Paracha A, Zulfiqar S (1994) Thermal degradation of glycidyl methacrylate-styrene copolymers. Polym Degrad Stabil 43:403-408. https://doi.org/10.1016/0141-3910(94)90012-4 Zulfiqar S, Zulfiqar M, Nawaz M (1990) Thermal degradation of poly(glycidyi methacrylate). Polym Degrad Stabil 30:195-203. https://doi.org/10.1016/0141-3910(90)90075-I Piracha A, Zulfiqar S (1996) The thermal degradation of glycidyl methacrylate-methyl methacrylate copolymers. Polym Degrad Stabil 51:27-34. https://doi.org/10.1016/0141-3910(95)00172-7 Cite Share Download PDF Status: Published Journal Publication published 12 Sep, 2024 Read the published version in Journal of Polymer Research → Version 1 posted Reviewers agreed at journal 13 Apr, 2024 Reviewers invited by journal 08 Apr, 2024 Editor invited by journal 03 Apr, 2024 Editor assigned by journal 02 Apr, 2024 First submitted to journal 01 Apr, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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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-4204404","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":288646511,"identity":"1fe5a22b-df68-4e27-89c6-9daed2c33308","order_by":0,"name":"Liting Sun","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Liting","middleName":"","lastName":"Sun","suffix":""},{"id":288646512,"identity":"ee413a70-29ce-4aaf-aeb3-7b465c3ad724","order_by":1,"name":"Mingdong Li","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Mingdong","middleName":"","lastName":"Li","suffix":""},{"id":288646513,"identity":"3846943a-0f70-4cc9-9a20-dbb3f733431a","order_by":2,"name":"Bing Nie","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Bing","middleName":"","lastName":"Nie","suffix":""},{"id":288646514,"identity":"be4c23bc-3e18-4ddc-900c-6e21c872e4b9","order_by":3,"name":"Jianying Ma","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA70lEQVRIiWNgGAWjYHCChANAgoeBgfnAgQ8GNnakaGFLfDijIC2ZFNt4lI15PhxibCCkTrf9wMMDP3ccljHnX8MmbWNwgJmB/fDRDfi0mJ1JSDjYe+Ywj+WMt8ekcwzu8DHwpKXdwKvlQELCAd62wzwGN86lAbU8Y2aQ4DHDr+X8g4SDf8FazphJWxgcZmwgqOVGQsJhsC3ne4yNGYjT8iDhsGxbOtAWYCD3GKQlsxH0y/mc5I9v26ztDc4fPnDgxx8bO372w8fwagFGRwKQaGZgkEiA8NnwKwcB9gNAoo6Bgf8AYbWjYBSMglEwMgEALytVrXs/0QAAAAAASUVORK5CYII=","orcid":"","institution":"","correspondingAuthor":true,"prefix":"","firstName":"Jianying","middleName":"","lastName":"Ma","suffix":""},{"id":288646515,"identity":"dfbcaa95-bfb8-4d30-b48d-3b788f46de85","order_by":4,"name":"Chunlei Cao","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Chunlei","middleName":"","lastName":"Cao","suffix":""}],"badges":[],"createdAt":"2024-04-02 06:46:10","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4204404/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4204404/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s10965-024-04101-5","type":"published","date":"2024-09-12T15:57:47+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":54588041,"identity":"88117079-eae1-4851-9e32-c10e73871e5a","added_by":"auto","created_at":"2024-04-12 16:21:38","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":53655,"visible":true,"origin":"","legend":"\u003cp\u003eFTIR spectrum: \u003cstrong\u003ea\u003c/strong\u003e EPDM; \u003cstrong\u003eb\u003c/strong\u003e free copolymers; \u003cstrong\u003ec\u003c/strong\u003e grafted copolymers\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-4204404/v1/8ffe96fef2100284e29e32dc.png"},{"id":54587419,"identity":"291a7a66-96e6-4e2b-ab47-e653c13590a6","added_by":"auto","created_at":"2024-04-12 16:13:38","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":63783,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of initiator content on graft copolymerization\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-4204404/v1/4efb80049312a45764c80510.png"},{"id":54587247,"identity":"d989c705-3bd6-4e9b-8f95-6cc5d676cc79","added_by":"auto","created_at":"2024-04-12 16:05:38","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":69831,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of chain transfer agent content on graft copolymerization\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-4204404/v1/dd8d13cb784b211046835500.png"},{"id":54587256,"identity":"915a3d85-7851-4245-9ca5-1c77f43d5d07","added_by":"auto","created_at":"2024-04-12 16:05:39","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":78086,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of EPDM content on graft copolymerization\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-4204404/v1/04f7af6ec6ce8e8446f0a35d.png"},{"id":54587250,"identity":"718a078d-4f25-47b5-85ff-c280019761eb","added_by":"auto","created_at":"2024-04-12 16:05:39","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":73055,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of GMA content on graft copolymerization\u003c/p\u003e","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-4204404/v1/dbf52ad33429cd4dd0b4ea6d.png"},{"id":54587255,"identity":"032035b5-79ba-4dfd-b857-fc5a98abbc40","added_by":"auto","created_at":"2024-04-12 16:05:39","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":63504,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of initiator content on molecular weights and their distributions of free copolymers\u003c/p\u003e","description":"","filename":"floatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-4204404/v1/9241fe1fc9a4fdcdc8f91964.png"},{"id":54587421,"identity":"bd2b82ea-a652-429a-99a2-4a7418256425","added_by":"auto","created_at":"2024-04-12 16:13:39","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":64291,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of chain transfer agent content on molecular weights and their distributions of free copolymers\u003c/p\u003e","description":"","filename":"floatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-4204404/v1/a7c4e0dff4910a8503fc2b36.png"},{"id":54587254,"identity":"7f90c7af-6931-4b78-bca0-04654cae7969","added_by":"auto","created_at":"2024-04-12 16:05:39","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":65149,"visible":true,"origin":"","legend":"\u003cp\u003eEffects of EPDM content on molecular weights and their distributions of free copolymers\u003c/p\u003e","description":"","filename":"floatimage8.png","url":"https://assets-eu.researchsquare.com/files/rs-4204404/v1/a4526e0987f4bc82441e2dec.png"},{"id":54588042,"identity":"8a2d2270-d93f-42aa-b974-e08067f1c52b","added_by":"auto","created_at":"2024-04-12 16:21:39","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":64232,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of GMA content on molecular weights and their distributions of free copolymers\u003c/p\u003e","description":"","filename":"floatimage9.png","url":"https://assets-eu.researchsquare.com/files/rs-4204404/v1/f6e82c8ff9e7b4c6a37b27b0.png"},{"id":54587252,"identity":"01b74852-d8ca-4c72-afcd-ecd480c2c3de","added_by":"auto","created_at":"2024-04-12 16:05:39","extension":"jpg","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":237957,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of polymerization conditions on composition of free copolymers:\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ea \u003c/strong\u003einitiator; \u003cstrong\u003eb\u003c/strong\u003e chain transfer agent; \u003cstrong\u003ec\u003c/strong\u003e EPDM; \u003cstrong\u003ed\u003c/strong\u003e GMA\u003c/p\u003e","description":"","filename":"10.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4204404/v1/f26909e52cabea89941e29ad.jpg"},{"id":54587258,"identity":"78202c40-4be5-4d22-a1b8-512896ae4e77","added_by":"auto","created_at":"2024-04-12 16:05:40","extension":"jpg","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":170571,"visible":true,"origin":"","legend":"\u003cp\u003eEffect of GMA content on thermal stabilities of GAES resins:\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ea \u003c/strong\u003eTG curves; \u003cstrong\u003eb\u003c/strong\u003e DTG curves\u003c/p\u003e","description":"","filename":"11.jpg","url":"https://assets-eu.researchsquare.com/files/rs-4204404/v1/f9276c822f904f8a58edf211.jpg"},{"id":64619149,"identity":"cbd3a394-f360-4d16-9150-9b6129ee4aec","added_by":"auto","created_at":"2024-09-16 16:11:58","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1432232,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4204404/v1/7cab7d2b-95df-4816-90f0-ca46b29765ea.pdf"}],"financialInterests":"","formattedTitle":"Preparation of epoxy-functionalized AES (GAES) resins by high-temperature bulk polymerization","fulltext":[{"header":"Introduction","content":"\u003cp\u003ePolyester materials such as polycarbonate (PC) [\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], poly(butylene terephthalate) (PBT) [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e] and polyamide 6 (PA6) [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e], as high-performance engineering plastics, play an important role in agriculture, industry and food packaging because of their good processability and mechanical properties. However, the inherent high notch sensitivity of polyester materials impose limitations on their suitability for certain applications in some fields [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Therefore, it is imperative to enhance the toughness of polyester materials. Currently, the most cost-effective and efficient approach involves physical blending with toughening agents to fabricate polymer composites. The following four kinds of toughening agents are usually applied in physical blending: rubbers, thermoplastic elastomers, traditional petroleum-based plastics, and inorganic nanoparticles [\u003cspan additionalcitationids=\"CR9\" citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. Inorganic nanoparticles are frequently compounded with rubbers or thermoplastic elastomers to achieve the effect of synergistic toughening. Thermoplastic elastomers exhibit superior toughening performance compared to other types of toughening agents due to the unique structure containing both plastic (hard) and rubber (soft) segments [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Among them, ABS resins with core-shell structure have been extensively investigated for their potential in enhancing the toughness of polyester [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eTheoretically, the use of physical blending method can effectively enhance the polymer\u0026rsquo;s toughness. However, the toughening effect is usually unsatisfactory because of the poor compatibility between polymers and toughening agent [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Therefore, the compatibilizers are necessary and often added to enhance the compatibility of two phases during the process of physical blending, thus improving the overall performance of composites [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Alternatively, the toughening agents can be modified by incorporating some monomers with high reactivity [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. Then the modified toughening agents reacted with toughened polymers, and promoted the formation of block or graft copolymers, thereby enhancing the compatibility of two phases [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. Functionalization of toughening agent improve the toughening effect compared to the previous method [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAt present, the functional monomers, such as acrylic acid (AA), maleic anhydride (MAH) [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e], glycidyl methacrylate (GMA) [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e], were often used most in the studies of functionalization of ABS resins [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. During the process of melt blending, the reactive groups can react with the inherent groups of polyesters to form block or graft copolymers in situ at interface of two phases, which improve the compatibility of two phases [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. The current research primarily employ the melt extrusion or emulsion polymerization methods. Nevertheless, the grafting rate achieved through melt extrusion is relatively lower and fails to obtain significant enhancement effects. The emulsion polymerization can obtain a higher grafting rate, but its implementation on a large scale is hindered by the complexity of the subsequent processing steps.\u003c/p\u003e \u003cp\u003eIn addition, due to the high processing temperature of PC, PBT, PA6 and other polymers, the long-term high temperature will lead to oxidative degradation of the unsaturated double bond in ABS resins and reduce the toughening effect, which will result in decline of overall performance of composites [\u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. The researches show that the use of saturated rubbers instead of polybutadiene rubbers in ABS resins is a good solution to this problem [\u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e26\u003c/span\u003e]. Among them, the use of EPDM rubbers in AES resins which not only prevent polymers from oxidative degradation at high processing temperatures, but also endow polymers with better weather resistance.\u003c/p\u003e \u003cp\u003eTherefore, the aim of our paper is to synthesize epoxy-functionalized AES resins (GAES resins) by high-temperature bulk polymerization, and functional monomers (GMA) were introduced in the synthesis of GAES resins. The method is characterized and proved by the fact that when the products are used as toughening agent, there is no need to add compatibilizer, and the products can form block or graft copolymers with polyesters in situ to improve the compatibility of two phases. The products synthesized by high-temperature bulk polymerization usually have special morphologies, such as internal inclusion structure, salami structure, and the existence of these structures can effectively improve the toughening effect. In addition, the products obtained by high-temperature bulk polymerization usually possess the following advantage when compared with emulsion polymerization and solution polymerization: purity of products, continuous production, short experimental period, and less pollution to environment [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eWhen AXS resins are used as toughening agents to toughen polyesters, the grafting rate of resins [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e, \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e29\u003c/span\u003e], molecular weights and distributions of free copolymers, and phase morphologies are important factors to determine toughening effect [\u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e30\u003c/span\u003e, \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e31\u003c/span\u003e]. Therefore, this paper focuses on the effects of polymerization conditions, i.e. content of initiator and chain transfer agent, content of EPDM and TDM, on graft copolymerization reaction of GAES resins and compositions, molecular weights and distributions of free copolymers. Meanwhile, the effect of GMA content on thermal stability of GAES resins were also discussed.\u003c/p\u003e"},{"header":"Experimental","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\n\u003ch2\u003eMaterials\u003c/h2\u003e\n\u003cp\u003eAcrylonitrile and ethylbenzene (industrial grade, Petro China Jilin Petrochemical Company, China) were purified by means of distillation. Styrene (industrial grade, Petro China Fushun Petrochemical Company, China) was washed with 5% aqueous sodium hydroxide, subsequently washed with water to neutral, dried with anhydrous sodium sulfate, and finally distilled under vacuum. Glycidyl methacrylate (industrial grade, Nanjing Rongxin Chemical Technology Co., Ltd, China) was purified by means of distillation. EPDM (industrial grade, Petro China Jilin Petrochemical Company, China) was dried at 60 \u003csup\u003eo\u003c/sup\u003eC for 12 hours in vacuum. Di-tert-butyl peroxide (DTBP) and tert-dodecyl mercaptan (TDM) (chemical pure, Sinopharm Chemical Reagent Co., Ltd., China) were used directly.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\n\u003ch2\u003eSynthesis of GAES resin\u003c/h2\u003e\n\u003cp\u003eGAES resins were prepared using high-temperature bulk polymerization, and the experimental formulations were shown in Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e. The preparation process was carried out according to the following steps: solvent and monomers (acrylonitrile, styrene and glycidyl methacrylate) were added into the reactor and a certain amount of EPDM was added under low-speed stirring conditions, where the mass ratio of St to AN was 3:1. Nitrogen was used to exhaust the air in the kettle, and pre-swelling was carried out under high-speed stirring conditions to ensure the rubbers were fully dissolved. Subsequently, a certain content of DTBP, TDM and a small amount of solvent were pumped into reaction kettle under a certain pressure of nitrogen, and the reaction temperature was raised to set temperature 130 \u003csup\u003eo\u003c/sup\u003eC which was chosen as reaction temperature in this paper due to the half-life of DTBP at 130 \u003csup\u003eo\u003c/sup\u003eC of 0.15 h. A small amount of resins was removed from the discharge port of reactor every ten minutes for measurement of conversion rate. The reaction was terminated when the conversion rate reached 80%. The polymerization products were finally subjected to devolatilization.\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n\u003ctable id=\"Tab1\" border=\"1\"\u003e\u003ccaption\u003e\n\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n\u003cdiv class=\"CaptionContent\"\u003e\n\u003cp\u003eFormulas of synthesis of GAES resins\u003c/p\u003e\n\u003c/div\u003e\n\u003c/caption\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eexperiment\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eTemperature\u003c/p\u003e\n\u003cp\u003e(\u003csup\u003eo\u003c/sup\u003eC)\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003einitiator\u003c/p\u003e\n\u003cp\u003e(wt%)\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003echain transfer agent\u003c/p\u003e\n\u003cp\u003e(wt%)\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003erubber\u003c/p\u003e\n\u003cp\u003e(wt%)\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eGMA\u003c/p\u003e\n\u003cp\u003e(wt%)\u003c/p\u003e\n\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003ea.\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e130\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e0.05\u0026thinsp;~\u0026thinsp;0.25\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e0.2\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e20\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e2\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eb.\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e130\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e0.1\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e0.05\u0026thinsp;~\u0026thinsp;0.25\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e20\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e2\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003ec.\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e130\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e0.1\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e0.2\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e20\u0026thinsp;~\u0026thinsp;60\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e2\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003ed.\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e130\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e0.1\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e0.2\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e40\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e2\u0026thinsp;~\u0026thinsp;10\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003ctfoot\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"6\"\u003eNote: content of initiator and chain transfer agent were varied by 0.05 wt%, content of rubber was varied by 10 wt%, and content of GMA was varied by 2 wt%.\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tfoot\u003e\n\u003c/table\u003e\n\u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\n\u003ch2\u003eGrafting rate\u003c/h2\u003e\n\u003cp\u003eThe grafting rate was determined by method of high-speed centrifugation: the dried GAES resins samples (W\u003csub\u003e1\u003c/sub\u003e g) were added into a centrifuge tube with 20 mL of acetone, and then placed in SHA-B type water-bath thermostatic oscillator (Jiangsu Jintan Hualong Experimental Instrument Factory, China). After 12 h of dissolution by constant temperature oscillation, the centrifuge tube was transfer to GL-21M ultracentrifuge (Shanghai Institute of Centrifugal Machinery, China) and centrifuged for 30 min at 10,000 r min\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. After centrifugation, the upper layer clear liquid was extracted and dissolved again by acetone for three times, finally the sample after supernatant extraction was dried in vacuum to constant weight (W\u003csub\u003e2\u003c/sub\u003e g). The grafting rate and grafting efficiency were calculated according to the following formulas [\u003cspan class=\"CitationRef\"\u003e32\u003c/span\u003e]:\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\n\u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(A=\\frac{{m}_{1}}{{m}_{1}+{m}_{2}\\times C}\\)\u003c/span\u003e\u003c/span\u003e (2\u0026thinsp;\u0026minus;\u0026thinsp;1)\u003c/p\u003e\n\u003cdiv id=\"Sec7\" class=\"Section3\"\u003e\n\u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(GR=\\frac{{W}_{2}-{W}_{1}\\times A}{{W}_{1}\\times A}\\)\u003c/span\u003e\u003c/span\u003e (2\u0026ndash;2)\u003c/p\u003e\n\u003cdiv id=\"Sec8\" class=\"Section4\"\u003e\n\u003cp\u003e\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(GE=\\frac{{W}_{2}-{W}_{1}\\times A}{{W}_{1}\\times \\left(1-A\\right)}\\)\u003c/span\u003e\u003c/span\u003e (2\u0026ndash;3)\u003c/p\u003e\n\u003cp\u003eA-weight ratio of rubbers in GAES resins; m\u003csub\u003e1\u003c/sub\u003e-mass of rubbers in the formulation (g); m\u003csub\u003e2\u003c/sub\u003e-mass of monomer in the formulation (g); C-monomer conversion.\u003c/p\u003e\n\u003c/div\u003e\n\u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e\n\u003ch2\u003eFTIR analysis\u003c/h2\u003e\n\u003cp\u003eFTIR were obtained on spectrometer measurements (Nicolet Magna-760, Nicolet Analytical Instruments, Madison, WI). The grafted copolymers and EPDM rubbers were subjected to ATR-FTIR testing using hot-pressed films. The free copolymers were tested using smear method by dipping a drop solution of this substance onto a KBr sheet and baking in an oven to remove solvent before testing. IR spectra were recorded in a wave range of 400\u0026ndash;4000 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003e\u003csup\u003e \u003cstrong\u003e1\u003c/strong\u003e\u003c/sup\u003e\u003cstrong\u003eH-NMR analysis\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003csup\u003e1\u003c/sup\u003eH-NMR spectra were acquired using a nuclear magnetic resonance superconducting instrument (Bruker Avance III 400, Bruker Company, USA). A certain amount of polymers were dissolved in CDCl\u003csub\u003e3\u003c/sub\u003e. The copolymer composition and structures were calculated by comparing the five proton signals at 6.5\u0026ndash;7.5 ppm for benzene ring group of St, the proton signals at 3.61\u0026ndash;3.81 ppm for -OCH\u003csub\u003e2\u003c/sub\u003e- group of GMA, and the proton signals on cyanine-adjacent carbon atoms of AN at 2.25\u0026ndash;2.33 ppm [\u003cspan class=\"CitationRef\"\u003e33\u003c/span\u003e].\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e\n\u003ch2\u003eMolecular weights of free copolymers\u003c/h2\u003e\n\u003cp\u003eThe free copolymers were obtained by drying the supernatant after centrifugation. The samples dissolved in THF and formed a solution with concentration of 0.1%. The molecular weights of free copolymers and their distributions were measured by Waters 2414 Refractive Index Detector (DRI) with a flow rate of 1 mL min\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for the eluent. The linear polystyrene was used as standard sample, and the temperature was 35 \u003csup\u003eo\u003c/sup\u003eC.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\n\u003ch2\u003eThermal stability analysis\u003c/h2\u003e\n\u003cp\u003eThermal decomposition behaviors were examined by mean of TG with a heating rate of 10 \u003csup\u003eo\u003c/sup\u003eC min\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e from 30 \u003csup\u003eo\u003c/sup\u003eC to 650 \u003csup\u003eo\u003c/sup\u003eC under nitrogen atmosphere on thermogravimetric analyzer (TG209, NETZCH, Germany).\u003c/p\u003e\n\u003c/div\u003e"},{"header":"Results and discussion","content":"\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\n\u003ch2\u003eStructure characterization of graft copolymers\u003c/h2\u003e\n\u003cp\u003eThe structures of GAES resins components were determined by FTIR spectroscopy. As shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e, the absorption peak at 2240 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e was characteristic of telescopic vibration peak of carbon nitrogen triple bond (C\u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\equiv\\)\u003c/span\u003e\u003c/span\u003eN). The peak at 1730 cm\u003csup\u003e\u0026minus;1\u003c/sup\u003e was characteristic of telescopic vibration peak of carbonyl (C\u0026thinsp;=\u0026thinsp;O). The two peaks at 760 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 700 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e were characteristic of bending vibration peak of mono-substituted benzene ring, which were not present in the spectrum of EPDM. These results indicated that the grafting reaction had taken place and the GAES grafting copolymers were successfully prepared.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec14\" class=\"Section2\"\u003e\n\u003ch2\u003eEffect of polymerization conditions on grafting rate\u003c/h2\u003e\n\u003cp\u003eIn this paper, DTBP was chosen as initiator, and the reaction was carried out in ethylbenzene. The content of EPDM, GMA and chain transfer agent was 20 wt%, 2 wt% and 0.2 wt%, respectively. The reaction temperature was kept constant at 130 \u003csup\u003eo\u003c/sup\u003eC, and the effect of initiator content on grafting reaction was discussed. The experimental results were shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e, it can be seen that the grafting rate first increased and then decreased with increasing content of initiator, and reached the highest value when the initiator content was 0.2 wt%. Meanwhile, the grafting efficiency increased with increasing content of initiator. The reason for this phenomenon was that the concentration of free radicals in reaction system increased with increasing content of initiator, which was favorable for the grafting reaction [\u003cspan class=\"CitationRef\"\u003e32\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e34\u003c/span\u003e]. However, when the initiator content exceeded 0.2 wt%, the grafting rate showed a tendency of slight decrease. We know the grafting rate is defined as the ratio of the total mass of successfully grafted monomers to the total mass of rubbers. The grafting rate mainly depended on the total mass of grafted monomers when the rubber content was fixed. Therefore, the decrease of grafting rate were related to the length of grafting chains, which were explored in detail in subsequent studies. Based on the results above, the initiator content of 0.2 wt% was chosen for subsequent experiments.\u003c/p\u003e\n\u003cp\u003eThe effect of chain transfer agent content on graft copolymerization were shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e. TDM was chosen as chain transfer agent, and the grafting reaction was carried out in ethylbenzene. The content of EPDM, GMA and initiator 20 wt%, 2 wt% and 0.2 wt%, respectively. The reaction temperature was constant at 130 \u003csup\u003eo\u003c/sup\u003eC. As can be seen from Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e, the grafting rate of GAES resins showed an obvious decreasing trend with increasing content of chain transfer agent while the other polymerization conditions were unchanged. It was noteworthy that the more content of chain transfer agent, the slower decrease trend of grafting rate, the grafting rate was only 16.71% when the content of chain transfer agent was 0.25 wt%. The reason for the significant decrease in grafting rate can be attributed to two points: firstly, the addition of chain transfer agent reduced the probability of chain transfer of free radicals to EPDM molecular chains, which led to a decrease in the number of active centers on EPDM molecular chains, and further reduced the probability of the formation of branched chains on EPDM molecular chains. Secondly, the introduction of chain transfer agent predominantly led to termination of free copolymers chains through chain transfer to chain transfer agent, thereby significantly reducing the radical coupling termination with EPDM molecular chains and consequently diminishing branching probability via coupling termination in EPDM molecular chains.\u003c/p\u003e\n\u003cp\u003eThe results above indicated that the highest grafting rate was obtained when the content of initiator and chain transfer agent were 0.2 wt% and 0.1 wt%, respectively, and these two contents were chosen for the following experiments. Figure\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e revealed the effect of EPDM content on graft copolymerization. The results showed that the grafting rate first increased and then decreased with increasing content of EPDM, and reached the maximum value of 51.45% at 30 wt% content of EPDM. This change stemmed from two main sources [\u003cspan class=\"CitationRef\"\u003e34\u003c/span\u003e]: first, the viscosity of reaction system increased with increasing content of EPDM, which limited the migration of monomer radicals to EPDM chains and made it difficult to terminate to EPDM molecular chains, finally led to decreasing of grafting rate. Second, the increase content of EPDM was equivalent to the decrease concentration of copolymerized monomers, which resulted in lower concentration of monomer radicals and reducing the probability of transfer to rubber chains, and in turn led to a rapid decrease of grafting rate. The grafting efficiency monotonically increased with increasing content of EPDM, which attributed to the fact that EPDM molecular chains provided more grafting sites at high content of EPDM, enabling more monomer radicals to successfully graft onto EPDM molecular chains. Taken together, 40 wt% content of EPDM was determined as the optimal polymerization condition in this paper.\u003c/p\u003e\n\u003cp\u003eThe effect of GMA content on graft copolymerization was investigated. The content of EPDM, initiator and chain transfer agent was 40 wt%, 0.2 wt% and 0.1 wt%, respectively, and the reaction temperature was130\u0026deg;C. The experimental results were shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e, the grafting rate of GAES resins exhibited a trend of first decrease and then increase with increasing content of GMA. It was mainly because of the larger difference of polarity between GMA and AN [\u003cspan class=\"CitationRef\"\u003e35\u003c/span\u003e], the addition of GMA had influence on the ideal copolymerization ratio of AN to St. Meanwhile, the activity of AN radicals were more higher than that of GMA radicals, and therefore the ability of capturing hydrogen from rubber chains was stronger than that of GMA radicals. The monomers were more inclined to undergo copolymerization reaction with increasing content of GMA, which affected the grafting rate and grafting efficiency of GAES resins.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec15\" class=\"Section2\"\u003e\n\u003ch2\u003eEffect of polymerization conditions on molecular weights and composition of free copolymers\u003c/h2\u003e\n\u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003e showed the effect of initiator content on molecular weights and their distributions of free copolymers. The molecular weights of free copolymers slowly decreased with increasing content of initiator. The reason for this phenomenon was that the increase content of initiator led to increasing concentration of monomer radicals in reaction system, which in turn led to increasing number of active centers. However, with increasing concentration of monomer radicals in reaction system, the excess radicals were not all effective for initiating polymerization reaction due to the short survival time of radicals, thus increasing the probability of termination of double radical coupling and resulting in rapid chain termination of polymers and lowering the molecular weights of copolymers. This phenomenon explained the reason for decreasing of grafting rate when the content of initiator exceeded 0.2 wt%. Meanwhile, the molecular weights distribution of free copolymers became narrower with increasing content of initiator.\u003c/p\u003e\n\u003cp\u003eThe effect of chain transfer agent content on molecular weights and their distributions of free copolymers were shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003e. The content of EPDM, GMA and initiator was 20 wt%, 2 wt% and 0.2 wt%, respectively. The reaction temperature was kept constant at 130 \u003csup\u003eo\u003c/sup\u003eC. It can be seen that chain transfer agent had a strong regulating influence on molecular weights of free copolymers, which was in line with the basic law of free radical polymerization, the molecular weights of copolymers decreased gradually with increasing content of chain transfer agent [\u003cspan class=\"CitationRef\"\u003e36\u003c/span\u003e]. When the content of chain transfer agent was 0.1 wt%, the molecular weights of copolymers reached about 97000 g mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, and then remained basically unchanged after the content of chain transfer agent exceeded 0.15 wt%. There were two main chain transfer reactions in the reaction system: the transfer reactions to macromolecular chains and chain transfer agent. The ability of transfer to macromolecular chains was fixed because of the constant content of EPDM, the initiation efficiency of chain transfer agent was not improved with increasing content of chain transfer agent. Therefore, the molecular weights remained basically unchanged when the content of chain transfer agent exceeded 0.15 wt%. The content of chain transfer agent had slightly influence on molecular weights distribution and the PDI maintained about 1.7.\u003c/p\u003e\n\u003cp\u003eThe effects of EPDM content on molecular weights and their distributions of free copolymers were shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e8\u003c/span\u003e. Here the content of initiator, chain transfer agent, and GMA was 0.2 wt%, 0.1 wt% and 2 wt%, respectively. It can be seen that the content of EPDM had important influence on molecular weights of free copolymers, and the molecular weights decreased with increasing content of EPDM, especially the molecular weights decreased rapidly when the content of EPDM exceeded 40 wt%. Meanwhile, the molecular weights distributions were fluctuated around 1.6. The high content of rubbers increased the viscosity of polymerization system obviously and reduced the concentration of monomers, which resulted in decreasing of molecular weights of free copolymers. We thought the effect of EPDM content on molecular weights and molecular weights distribution mainly depended on the increasing viscosity of reaction system. when the viscosity of reaction system was higher, the effect of heat and mass transfer became more difficult, the temperature increased and the concentration distribution of reaction system became more wider, and it was easy to form gradient distribution, which finally resulted in increasing of molecular weights distribution.\u003c/p\u003e\n\u003cp\u003eThe relationships of GMA content and molecular weights, and their distributions of free copolymers were studied and shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e9\u003c/span\u003e. Here the content of initiator, chain transfer agent, and EPDM was 0.2 wt%, 0.1 wt% and 40 wt%, respectively. It can be seen that the molecular weights of free copolymers basically remained unchanged with increasing content of GMA, and the molecular weights decreased rapidly when the content of GMA exceeded 8 wt%. The increasing content of GMA led to a higher concentration of epoxy groups in free copolymers, thereby enhanced the site-blocking effect and impeded the attack of free radicals, ultimately resulted in decreasing of molecular weights. The molecular weights distribution decreased with increasing content of GMA and finally maintained around 1.5.\u003c/p\u003e\n\u003cp\u003eThe effect of polymerization conditions on the composition of free copolymers was shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e10\u003c/span\u003e. The experimental formulas were shown in Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e. It can be observed from Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e10\u003c/span\u003e(a) and Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e10\u003c/span\u003e(b) that there were little influence on the compositions of free copolymers with increasing content of initiator and chain transfer agent. For Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e10\u003c/span\u003e(c), the component of GMA in free copolymers increased with increasing content of EPDM, but had little influence on the component of St and AN. The grafting reaction and copolymerization reaction in reaction system were the relationship of competition, the viscosity of reaction system increased with increasing content of EPDM, so that the transfer of mass and heat became more difficult, and the grafting reaction was inhibited. The larger spatial resistance of epoxy groups in GMA monomer made it difficultly move to EPDM chains, and the copolymerization reaction was more favored, which the content of GMA within free copolymers increased with increasing content of EPDM. From Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e10\u003c/span\u003e(d), it can be found that with increasing content of GMA in free copolymers, the compositions of GMA and AN gradually increased, and the composition of St gradually decreased, which were attributed to the different polarity of these several monomers. Both GMA and AN were polar monomers, the compatibility of the two monomers was better according to the principle of similar dissolution, and St itself as a non-polar monomer was not good compatibility with the other monomers. The polarity of reaction system was gradually increased with increasing content of GMA, which led to decreasing component of St in free copolymers.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec16\" class=\"Section2\"\u003e\n\u003ch2\u003eThermal stabilities of GAES resins\u003c/h2\u003e\n\u003cp\u003eThermogravimetric testing of EPDM and GAES resins containing 2 wt%, 4 wt%, 6 wt%, 8 wt%, and 10 wt% (denoted as EPDM, GAES-2, GAES-4, GAES-6, GAES-8, and GAES-10, respectively) were carried out under N\u003csub\u003e2\u003c/sub\u003e atmosphere at a temperature increase rate of 10\u0026deg;C min\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, the TG and DTG curves were shown in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e11\u003c/span\u003e. The initial decomposition temperature (T\u003csub\u003ein\u003c/sub\u003e), half weight-loss temperature (T\u003csub\u003e50%\u003c/sub\u003e), terminal decomposition temperature (T\u003csub\u003eend\u003c/sub\u003e) and maximum weight-loss temperature (T\u003csub\u003emax\u003c/sub\u003e) were characterized and compared. From Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e11\u003c/span\u003e(a), it can be seen that the thermal degradation behaviors of GAES resins were basically similar, the T\u003csub\u003ein\u003c/sub\u003e, T\u003csub\u003e50%\u003c/sub\u003e, T\u003csub\u003eend\u003c/sub\u003e and T\u003csub\u003emax\u003c/sub\u003e of GAES resins gradually decreased with increasing content of GMA. Table. 2 recorded the thermal degradation temperatures at each stage of thermal degradation and the maximum weight-loss temperatures of EPDM and GAES resins with different content of GMA. T\u003csub\u003ein\u003c/sub\u003e of GAES resins decreased about 12 \u003csup\u003eo\u003c/sup\u003eC when the content of GMA increased from 2 to 10 wt%. T\u003csub\u003ein\u003c/sub\u003e was used as a criterion for evaluating the thermal stabilities of polymers. The decreasing of T\u003csub\u003ein\u003c/sub\u003e indicated the incorporation of GMA monomers decreased the thermal stabilities of GAES resins, and the more content of GMA, the worse thermal stabilities of GAES resins. As can be seen from Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e11\u003c/span\u003e(b), when the content of GMA exceeded 8 wt%, a bimodal structure with two extreme values appeared on DTG curves. It was related to the properties of GMA monomer itself, the thermal degradation process of GMA under high temperature conditions was divided into two stages. The first degradation stage was the process of removing small molecular groups, which generated gases, such as CO, CO\u003csub\u003e2\u003c/sub\u003e, or CH\u003csub\u003e3\u003c/sub\u003e. The second stage was the process of random chain breakage of the residue [\u003cspan class=\"CitationRef\"\u003e37\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e39\u003c/span\u003e]. With increasing content of GMA in GAES resins, the number of small molecular groups which removed in first degradation stage gradually increased and the rate of weight-loss also gradually increased. Therefore, the bimodal structure gradually appeared with increasing content of GMA in DTG curves.\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n\u003ctable id=\"Tab2\" border=\"1\"\u003e\u003ccaption\u003e\n\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n\u003cdiv class=\"CaptionContent\"\u003e\n\u003cp\u003eTG/DTG data of EPDM and GAES resins with different content of GMA\u003c/p\u003e\n\u003c/div\u003e\n\u003c/caption\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003esample\u003c/p\u003e\n\u003c/th\u003e\n\u003cth colspan=\"3\" align=\"left\"\u003e\n\u003cp\u003eThermal degradation temperature of (\u003csup\u003eo\u003c/sup\u003eC)\u003c/p\u003e\n\u003c/th\u003e\n\u003cth colspan=\"2\" align=\"left\"\u003e\n\u003cp\u003ePeak temperature (\u003csup\u003eo\u003c/sup\u003eC)\u003c/p\u003e\n\u003c/th\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eT\u003csub\u003ein\u003c/sub\u003e\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eT\u003csub\u003e50%\u003c/sub\u003e\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eT\u003csub\u003eend\u003c/sub\u003e\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eT\u003csub\u003emax 1\u003c/sub\u003e\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eT\u003csub\u003emax 2\u003c/sub\u003e\u003c/p\u003e\n\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eEPDM\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e427\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e452\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e494\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e452\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eGAES-2\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e377\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e426\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e477\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e419\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eGAES-4\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e375\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e425\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e478\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e415\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eGAES-6\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e369\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e423\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e476\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e413\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e-\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eGAES-8\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e367\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e421\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e477\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e414\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e439\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eGAES-10\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e365\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e422\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"char\" char=\".\"\u003e\n\u003cp\u003e475\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e413\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e438\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003ctfoot\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"6\"\u003eNote: T\u003csub\u003emax1\u003c/sub\u003e and T\u003csub\u003emax2\u003c/sub\u003e represented peak temperatures of low-temperature and\u0026nbsp;high-temperature weight-loss peak.\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tfoot\u003e\n\u003c/table\u003e\n\u003c/div\u003e\n\u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eGAES resins were successfully prepared and the influence of polymerization conditions on the composition, molecular weights and distributions of free copolymers were investigated in detail, the effects of GMA content on thermal stabilities of GAES resins were also explored.\u003c/p\u003e\n\u003cp\u003eFirst, the GAES resins had the maximum grafting rate with 0.2 wt% content of initiator. The grafting rate decreased with increasing content of chain transfer agent. The grafting rate was the highest when the content of EPDM was 30 wt%. Second, the increase content of initiator and chain transfer agent, EPDM and GMA, all resulted in decreasing of molecular weights, among which the influence of EPDM was more significant. Third, the content of initiator and chain transfer agent had no significant influence on the composition of free copolymers, the GMA component of copolymers gradually increased with increasing content of EPDM. Finally, the thermal stabilities of GAES resins decreased with increasing content of GMA.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003cstrong\u003e \u003cb\u003eConflict of interest\u003c/b\u003e:\u003c/strong\u003e \u003cp\u003eThe authors affirm that there are no conflicts of interest to declare in relation to the research presented in this paper.\u003c/p\u003e \u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eRoberto G, Sorrentino A (1994) Polycarbonate/ABS blends: a literature review. Adv Polym Tech 13(4):249-258. https://doi.org/10.1002/adv.1994.06013 0401\u003c/li\u003e\n\u003cli\u003eQuintens D, Groeninckx G, Guest M (1990) Mechanical behavior related to the phase morphology of PC/SAN polymer blends. Polym Eng Sci 30(22):1474-1483. https://doi.org/10.1002/pen. 760302208\u003c/li\u003e\n\u003cli\u003eLiu B, Zhang Y, Wan CY, Shou WJ, Zhang YX, Su Y, Ji JL (2006) Rheological properties and morphology of PC/AES blends. 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Polym Degrad Stabil 51:27-34. https://doi.org/10.1016/0141-3910(95)00172-7\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":true,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"journal-of-polymer-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jpol","sideBox":"Learn more about [Journal of Polymer Research](https://www.springer.com/journal/10965)","snPcode":"10965","submissionUrl":"https://www.editorialmanager.com/jpol/","title":"Journal of Polymer Research","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Epoxy-functionalized AES resins, Grafting rate, Molecular weights, Free copolymers, Thermal stability","lastPublishedDoi":"10.21203/rs.3.rs-4204404/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4204404/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eIn this paper, the monomers of styrene (St), acrylonitrile (AN), and glycidyl methacrylate (GMA) were grafted onto ethylene-propylene-diene-monomer (EPDM) rubbers, and the epoxy-functionalized AES (GAES) resins were successfully prepared by high-temperature bulk polymerization. The effects of polymerization reaction conditions, i.e. the content of initiator and chain transfer agent, the content of EPDM and GMA on the grafting rate, composition of free copolymers, molecular weights and their distributions of GAES resins were investigated in detail. The influence of GMA content on the thermal stabilities of GAES resins were also discussed. Experimental results showed that under the optimized experimental conditions, the highest grafting rate of GAES resins reached to 48.8% and the grafting efficiency was 35.3%. Under the same reaction conditions, the molecular weights of free copolymers can reach to 70,000 g mol\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. The content of initiator and chain transfer agent had no obvious influence on the composition of free copolymers, but the component of GMA in free copolymers increased gradually with increasing content of EPDM. TG analysis results indicated that the incorporation of GMA decreased the thermal stabilities of GAES resins.\u003c/p\u003e","manuscriptTitle":"Preparation of epoxy-functionalized AES (GAES) resins by high-temperature bulk polymerization","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-04-12 16:05:32","doi":"10.21203/rs.3.rs-4204404/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"reviewerAgreed","content":"","date":"2024-04-14T02:13:10+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-04-08T06:12:57+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"Journal of Polymer Research","date":"2024-04-03T17:31:55+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-04-03T02:41:32+00:00","index":"","fulltext":""},{"type":"submitted","content":"Journal of Polymer Research","date":"2024-04-02T02:45:33+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"journal-of-polymer-research","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jpol","sideBox":"Learn more about [Journal of Polymer Research](https://www.springer.com/journal/10965)","snPcode":"10965","submissionUrl":"https://www.editorialmanager.com/jpol/","title":"Journal of Polymer Research","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"3c101b9d-2b4d-409b-81e9-9fb0694f19f9","owner":[],"postedDate":"April 12th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2024-09-16T16:03:12+00:00","versionOfRecord":{"articleIdentity":"rs-4204404","link":"https://doi.org/10.1007/s10965-024-04101-5","journal":{"identity":"journal-of-polymer-research","isVorOnly":false,"title":"Journal of Polymer Research"},"publishedOn":"2024-09-12 15:57:47","publishedOnDateReadable":"September 12th, 2024"},"versionCreatedAt":"2024-04-12 16:05:32","video":"","vorDoi":"10.1007/s10965-024-04101-5","vorDoiUrl":"https://doi.org/10.1007/s10965-024-04101-5","workflowStages":[]},"version":"v1","identity":"rs-4204404","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4204404","identity":"rs-4204404","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}