Toughening of epoxy resins by hydroxy-terminated, silicon-modified polyurethane oligomers
Toughening of epoxy resins by hydroxy-terminated, silicon-modified polyurethane oligomers
复制标题
DOI：
10.1002/app.12666
复制
发表时间：
2003-11-07
影响因子：
3
通讯作者：
Adhikari, B
中科院分区：
文献类型：
--
作者：
Bhuniya, S;Adhikari, B
环氧树脂是用途最广泛的工程结构材料之一。各种各样的环氧树脂是市售的，但大多数是脆性的。已经使用了几种方法来改善环氧树脂的韧性，包括添加填料、橡胶颗粒、热塑性塑料和它们的混合物，以及丙烯酸、聚氨酯和增韧剂如多元醇的互穿聚合物网络（IPN）。这最后一种方法没有得到太多的关注;它们中没有一种能够在不牺牲拉伸性能的情况下适当地增加树脂韧性。因此，为了填补这一空白，我们实验了新合成的羟基封端的硅改性聚氨酯（SiMPU）低聚物作为环氧树脂的增韧剂。以二甲基二氯硅烷、聚乙二醇（重均分子量约为200）和甲苯2，4-二异氰酸酯为原料，合成了SiMPU齐聚物，并用IR、1H-1 NMR、13 C-NMR和凝胶渗透色谱对其进行了表征。合成的SiMPU低聚物，以不同的浓度，形成IPN内的环氧树脂（双酚A的二缩水甘油醚）。将所得IPN产物用二氨基二苯基砜、二氨基二苯基醚和Ciba-Geigy硬化剂在各种固化条件下固化。各种机械性能，包括搭接剪切，剥离，和冲击强度，进行了评价。结果表明，SiMPU用量为15份时，环氧树脂的冲击强度最高，而拉伸性能没有下降。冲击强度不断增加，并在临界改性剂浓度（20份）达到最大值（5倍以上的原始树脂）。临界应力强度因子达到3.0 MPa m（1/2）（原始树脂仅为0.95 MPa m（1/2））。(C)2003 Wiley Periodicals，Inc.
Epoxy resins are among the most versatile engineering structural materials. A wide variety of epoxy resins are commercially available, but most are brittle. Several approaches have been used to improve the toughness of epoxy resins, including the addition of fillers, rubber particles, thermoplastics, and their hybrids, as well as interpenetrating polymer networks (IPNs) of acrylic, polyurethane, and flexibilizers such as polyols. This last approach has not received much attention; none of them have been able to suitably increase resin toughness with out sacrificing tensile properties. Therefore, in an attempt to fill this gap, we experimented with newly synthesized hydroxy-terminated silicon-modified polyurethane (SiMPU) oligomers as toughening agents for epoxy resins. SiMPU oligomers were synthesized from dimethyl dichlorosilane, poly(ethylene glycol) (weight-average molecular weight similar to 200), and toluene 2,4-diisocyanate and characterized with IR, H-1-NMR and C-13-NMR, and gel permeation chromatography. The synthesized SiMPU oligomers, with different concentrations, formed IPNs within the epoxy resins (diglycidyl ether of bisphenol A). The resultant IPN products were cured with diaminodiphenyl sulfone, diaminodiphenyl ether, and a Ciba-Geigy hardener under various curing conditions. Various mechanical properties, including the lap-shear, peel, and impact strength, were evaluated. The results showed that 15 phr SiMPU led to better impact strength of epoxy resins than the others without the deterioration of the tensile properties. The impact strength increased continuously and reached a maximum value (five times greater than that of the virgin resin) at a critical modifier concentration (20 phr). The critical stress intensity factor reached 3.0 MPa m(1/2) (it was only 0.95 MPa m(1/2) for the virgin resin). (C) 2003 Wiley Periodicals, Inc.