Effect of new hyperbranched polyester of varying generations on toughening of epoxy resin through interpenetrating polymer networks using urethane linkages
Effect of new hyperbranched polyester of varying generations on toughening of epoxy resin through interpenetrating polymer networks using urethane linkages
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DOI：
10.1016/j.eurpolymj.2013.06.041
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发表时间：
2013-11-01
影响因子：
6
通讯作者：
Pathak, Madhvesh
中科院分区：
文献类型：
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作者：
Dhevi, D. Manjula;Jaisankar, S. N.;Pathak, Madhvesh
在这项研究中，一个以前没有报道的方法，试图改善固有的脆性双酚A基环氧树脂的二缩水甘油醚使用超支化聚合物作为增韧剂。以双季戊四醇（作为核）和二羟甲基丙酸（AB（2）型单体）为原料，采用准一步熔融缩聚法合成了4种不同代数（1-4代）的超支化聚酯（HBP-G1 ~ HBP-G4）。新合成的HBP的特征在于使用光谱，热和物理测量，这证实了高度支化结构的形成和降低的热稳定性随着HBP代数的增加。此外，环氧树脂的增韧是通过使每一代HBP与环氧反应来进行的，使用二异氰酸酯作为中间键，导致形成HBP-聚氨酯/环氧-g-互穿聚合物网络（HBP-PU/EP-g-IPN）。为了比较，还合成了线性多元醇PU/EP-g-IPN。结果发现，HBP改性的环氧树脂样品表现出更高的韧性相比，纯环氧树脂和线性多元醇基环氧树脂样品。另一方面，由于柔性聚氨酯键的存在和环氧树脂基体交联密度的降低，改性样品的弯曲性能、热稳定性和玻璃化转变温度低于纯环氧样品。HBP所表现出的增韧特性从使用SEM数据的非均匀形态的存在得到证实。(C)2013爱思唯尔有限公司保留所有权利。
In this study, a previously unreported methodology is attempted to improve the inherent brittleness in diglycidyl ether of bisphenol-A based epoxy resin using hyperbranched polymers as toughening agents. Four different hyperbranched polyesters (HBPs) with increasing generations (1-4, denoted as HBP-G1 to HBP-G4) were synthesized by reacting calculated amount of dipentaerythritol (used as a core) and dimethylol propionic acid (AB(2) type monomer) through pseudo one-step melt polycondensation method. The newly synthesized HBPs were characterized using spectral, thermal and physical measurements, which confirmed the formation of highly branched structure and decreasing thermal stability with increasing HBP generations. Further, toughening of the epoxy resin is carried out by reacting each generation of the HBP with epoxy using hexamethylene diisocyanate as an intermediate linkage resulting in the formation of HBP-Polyurethane/Epoxy-g-Interpenetrating Polymer Networks (HBP-PU/EP-g-IPNs). A linear polyol-PU/EP-g-IPN is also synthesized for the purpose of comparison. It is found that the HBP modified epoxy samples exhibited higher toughness in comparison to that of neat epoxy and linear polyol based epoxy samples. On the other hand, flexural properties, thermal stability and glass transition temperature of the modified samples is lower than neat epoxy sample due to the existence of flexible urethane linkages and decrease in the cross-linking density of epoxy matrix. The toughening characteristics exhibited by the HBPs are corroborated from the existence of heterogeneous morphology using SEM data. (C) 2013 Elsevier Ltd. All rights reserved.