Nanostructure toughened epoxy resins
Nanostructure toughened epoxy resins
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DOI：
10.1021/ma034807y
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发表时间：
2003-12-16
期刊：
影响因子：
5.5
通讯作者：
Bates, FS
中科院分区：
文献类型：
--
作者：
Dean, JM;Verghese, NE;Bates, FS
提高脆性环氧树脂的断裂韧性通常是以牺牲模量和使用温度为代价的，这对这些树脂的使用产生了不可接受的限制。我们最近的努力集中在使用嵌段共聚物自组装来增韧环氧树脂，同时对玻璃化转变温度和模量的影响最小，并且具有简单的加工和低成本的优点。自组装成囊泡和胶束的1-5嵌段共聚物可以显著提高模型双酚A环氧树脂（如BPA348）在四功能芳香胺固化剂（如MDA）固化后的抗断裂能力。3、4球形胶束和囊泡具有相同的基本形状，但囊泡的尺寸越大，抗断裂能力增加3倍。在这里，我们引入了一种新型的自组装蠕虫状胶束改性剂，并证明了双酚a环氧树脂用酚醛树脂固化后的抗断裂性能显著提高，甚至对于含有溴化环氧树脂的环氧树脂配方也能提高阻燃性。此外，这种特殊的改进伴随着玻璃化转变温度的增加。这一发现对印刷电路板的制造和其他使用温度、阻燃性和韧性很重要的应用具有重要意义。本研究中使用的嵌段共聚物的聚合协议的完整描述在其他地方给出。两种类型的两亲性嵌段共聚物，聚（环氧乙烷）-聚（乙烯-丙烯）（PEO-PEP）和聚（甲基丙烯酸甲酯- trans -甲基丙烯酸缩水甘油酯）-聚（2-乙基己基甲基丙烯酸酯）（P (MMA-ran-GMA)-PEHMA）， 5, 7如图1所示。表1列出了嵌段共聚物的物理特性，包括环氧混相嵌段（PEO或P (MMA-ran-GMA)）的重量百分比和组成，以及嵌段共聚物的分子量和多分散体。
Increasing the fracture toughness of brittle epoxies often comes at the expense of modulus and use temperature, creating unacceptable limits on the use of these resins. Our recent efforts have concentrated on using block copolymer self-assembly to toughen epoxies with a minimal impact on the glass transition temperature and modulus and with the advantages of simple processing and low cost. 1-5 Block copolymers self-assembled into vesicles and micelles can significantly increase the fracture resistance of model bisphenol A epoxies (eg, BPA348) cured with a tetrafunctional aromatic amine curing agent (eg, MDA). 3, 4 Spherical micelles and vesicles share the same basic shape, but the larger dimensions of the vesicles produced up to a 3-fold increase in the fracture resistance. Here, we introduce a new type of modifier morphologysself-assembled wormlike micellessand demonstrate a remarkable enhancement in fracture resistance with a bisphenol A epoxy cured with phenol novolac, even for epoxy formulations containing brominated epoxies to improve flame retardation. Moreover, this exceptional improvement is accompanied by an increase in the glass transition temperature. This discovery has important implications for the manufacture of printed circuit boards and other applications where use temperature, flame retardation, and toughness are important.Complete descriptions of the polymerization protocols for the block copolymers used in this study are given elsewhere. 5-7 Two types of amphiphilic block copolymers, poly (ethylene oxide)-poly (ethylene-alt-propylene)(PEO-PEP) and poly (methyl methacrylate-ran-glycidyl methacrylate)-poly (2-ethylhexyl methacrylate)(P (MMA-ran-GMA)-PEHMA), were used, 5, 7 as illustrated in Figure 1. Table 1 lists the physical characteristics of the block copolymers including the weight percent and composition of the epoxy miscible blocks (PEO or P (MMA-ran-GMA)) and the block copolymer molecular weights and polydispersities.