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首页> 外文期刊>Polymer Degradation and Stability >Reactive processing of polymers: Functionalisation of ethylene-propylene diene terpolymer (EPDM) in the presence and absence of a co-agent and effect of functionalised EPDM on compatibilisation of poly(ethylene terephthalate)/EPDM blends
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Reactive processing of polymers: Functionalisation of ethylene-propylene diene terpolymer (EPDM) in the presence and absence of a co-agent and effect of functionalised EPDM on compatibilisation of poly(ethylene terephthalate)/EPDM blends

机译：聚合物的反应性处理：在存在和不存在助剂的情况下进行乙烯-丙烯二烯三元共聚物（EPDM）的官能化，以及官能化的EPDM对聚对苯二甲酸乙二酯/ EPDM共混物相容性的影响

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Ethylene-propylene diene terpolymer (EPDM) was functionalized with glycidyl methacrylate (GMA) during melt processing by free radical grafting with peroxide initiation in the presence and absence of a reactive comonomer trimethylolpropane triacrylate (Tris). Increasing the peroxide concentration resulted in an increase in the GMA grafting yield, albeit the overall grafting level was low and was accompanied by higher degree of crosslinking of EPDM which was found to be the major competing reaction. The presence of Tris in the grafting system gave rise to higher grafting yield produced at a much lower peroxide concentration though the crosslinking reactions remained high but without the formation of GMA-homopolymer in either of the two systems. The use of these functionalized EPDM (f-EPDM) samples with PET as compatibilisers in binary and ternary blends of PET/EPDM/f-EPDM was evaluated. The influence of the different functionalisation routes of the rubber phase (in presence and absence of Tris) and the effect of the level of functionality and microstructure of the resultant f-EPDM on the extent of the interfacial reaction, morphology and mechanical properties was also investigated. It is suggested that the mechanical properties of the blends are strongly influenced by the performance of the graft copolymer, which is in turn, determined by the level of functionality, molecular structure of the functionalized rubber and the interfacial concentration of the graft copolymer across the interface. The cumulative evidence obtained from torque rheometry, scanning electron microscopy, SEM, dynamic mechanical analysis (DMA), tensile mechanical tests and Fourier transform infrared (FTIR) supports this. It was shown that binary and ternary blends prepared with f-EPDM in the absence of Tris and containing lower levels of g-GMA effected a significant improvement in mechanical properties. This increase, particularly in elongation to break, could be accounted for by the occurrence of a reaction between the epoxy groups of GMA and the hydroxyl/carboxyl end groups of PET that would result in a graft copolymer which could, most probably, preferentially locate at the interface, thereby acting as an 'emulsifier' responsible for decreasing the interfacial tension between the otherwise two immiscible phases. This is supported by results from FTIR analysis of the fractionated PET phase of these blends which confirm the formation of an interfacial reaction, DMA results which show a clear shift in the T(g)s of the blend components and SEM results which reveal very fine morphology, suggesting effective compatibilisation that is concomitant with the improvement observed in their tensile properties. Although Tris has given rise to highest amount of g-GMA, it resulted in lower mechanical properties than the optimized blends produced in the absence of Tris. This was attributed to the difference in the microstructure of the graft and the level of functionality in these samples resulting in less favourable structure responsible for the coarser dispersion of the rubber phase observed by SEM, the lower extent of T-g shift of the PET phase (DMA), the lower height of the torque curve during reactive blending and FTIR analysis of the separated PET phase that has indicated a lower extent of the interfacial chemical reaction between the phases in this Tris-containing blend sample. (c) 2005 Elsevier Ltd. All rights reserved.
机译：在存在和不存在反应性共聚单体三羟甲基丙烷三丙烯酸酯（Tris）的情况下，通过自由基接枝和过氧化物引发，在熔融加工过程中用甲基丙烯酸缩水甘油酯（GMA）对乙烯-丙烯二烯三元共聚物（EPDM）进行功能化。过氧化物浓度的增加导致GMA接枝产率的增加，尽管总接枝水平较低，并伴有较高的EPDM交联度，这是主要的竞争反应。尽管交联反应仍然很高，但在两个系统中的任何一个中均未形成GMA均聚物，但接枝体系中Tris的存在可在较低的过氧化物浓度下产生更高的接枝产率。评估了这些功能化的EPDM（f-EPDM）样品与PET在PET / EPDM / f-EPDM的二元和三元共混物中的相容性。还研究了橡胶相的不同官能化途径（存在和不存在Tris）的影响以及所得f-EPDM的官能度和微结构水平对界面反应程度，形态和机械性能的影响。建议共混物的机械性能受到接枝共聚物性能的强烈影响，而接枝共聚物的性能又取决于官能度，官能化橡胶的分子结构以及接枝共聚物在界面上的界面浓度。从扭矩流变仪，扫描电子显微镜，SEM，动态力学分析（DMA），拉伸力学测试和傅立叶变换红外（FTIR）获得的累积证据支持了这一点。结果表明，在没有Tris的情况下，用f-EPDM制备的二元和三元共混物，其g-GMA含量较低，机械性能显着提高。这种增加，特别是断裂伸长率的增加，可以通过在GMA的环氧基和PET的羟基/羧基端基之间发生反应来解释，这将导致接枝共聚物很可能优先位于界面，从而充当“乳化剂”，负责降低在其他两个不混溶相之间的界面张力。这些混合物的分馏PET相的FTIR分析结果证实了界面反应的形成，DMA结果表明共混物组分的T（g）s发生了明显变化，而SEM结果表明非常精细，这证明了这一点。形态，表明有效的相容性，伴随着其拉伸性能的改善。尽管Tris产生了最高量的g-GMA，但与没有Tris的情况下生产的优化共混物相比，其机械性能却更低。这归因于这些样品中接枝物的微观结构和功能水平的差异，导致结构较差的有利结构，这导致通过SEM观察到的橡胶相的较粗分散，PET相的Tg位移较低（DMA） ），在反应混合过程中以及分离的PET相的FTIR分析过程中扭矩曲线的高度较低，表明该含Tris的混合物样品中各相之间的界面化学反应程度较低。 （c）2005 Elsevier Ltd.保留所有权利。

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