Thermal Stability of Imidized Epoxy Blends Initiated by N-Benzylpyrazinium Hexafluoroantimonate Salt
Thermal Stability of Imidized Epoxy Blends Initiated by N-Benzylpyrazinium Hexafluoroantimonate Salt
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DOI：
10.1021/ma010792x
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发表时间：
2001-09
期刊：
影响因子：
5.5
通讯作者：
Soojin Park;Hyun-Chel Kim;‡. A. W. Lee;D. Suh
中科院分区：
文献类型：
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作者：
Soojin Park;Hyun-Chel Kim;‡. A. W. Lee;D. Suh
双酚A环氧树脂（DGEBA）广泛用作飞机纤维复合材料的结构粘合剂，也用作印刷电路板的层压材料或半导体封装的模塑料。1，2然而，环氧树脂，由固化剂引发，往往会变得易碎，由于固有的性能，导致在自聚合过程中的高交联度。因此，环氧树脂的改性一直是人们研究的热点。因此，DGEBA和环氧树脂的共混物具有高的热性能，由于DGEBA的热性能的潜在改善而引起了人们的兴趣。在常用的环氧树脂/胺体系中，存在一些问题，如胺的毒性，在高温、高湿下的电性能劣化，以及固有的脆性行为。近年来，环氧化合物的阳离子聚合得到了广泛的研究。3，4阳离子环氧树脂配方在室温下避光条件下具有长期稳定性，暴露于高温时可快速固化。特别地，阳离子环氧体系可以改善电性能的劣化，这是由环氧/胺体系中的胺官能团的亲水性特征引起的。在阳离子机制中，环氧基团被活性质子（H+）打开，该质子可被金属置换以产生新的物理化学键或羟基。该催化剂通常作为络合物使用，例如BF 3-醚、BF 3-胺或SbF 6-环氧化物。该复合物克服了凝胶化过快、吸湿性大、光不稳定的缺点。特别地，开发用于阳离子聚合的潜催化剂对于提高热固性树脂的适用期和处理是期望的。5、6潜催化剂通常在热、光等外界刺激下形成活性物种，本工作的目的是研究高热性能环氧树脂（EMPT）对阳离子潜催化剂引发的DGEBA/EMPT体系热稳定性的影响。通过热重分析（TGA）对该体系的热稳定性进行了表征。本研究中使用的环氧树脂是双酚A的二缩水甘油醚（DGEBA，YD-128，由韩国Kukdo化学公司提供）。使用的另一种环氧树脂是间苯二胺双（1，2，3，6-四氢-3，4-环氧邻苯二甲酰亚胺）（EMPT），其在汉阳大学实验室中使用间苯二胺双（1，2，3，6-四氢-3，4-环氧邻苯二甲酰亚胺）（7.52 g，0.02 mol）作为二酰亚胺合成。7将粗产物在CHCl 3/乙醇（EA）（1/1）溶液中重结晶。最后，使用CHCl 3/EA（1/4）溶液作为洗脱剂，通过柱色谱法（70-230目）纯化产物。产物的颜色为白色，产量为4.0 g（49%）。产物的纯度和化学结构通过红外（FT-IR）光谱、1H NMR、13 C NMR和元素分析确认如下。对于FT-IR（KBr粒料）：3030 cm-1（芳族CH拉伸）、1780和1710 cm-1（酰亚胺CdO拉伸）、1383 cm-1（CN拉伸）、950-810 cm-1（不对称拉伸或环氧化物）。对于1H NMR（CDCl 3）：δ 7.6-7.4 ppm
Epoxy resins of bisphenol A (DGEBA) are extensively used as the structural adhesives in fiber composites for aircraft and also as the laminates in printed circuit boards or as the molding compounds for semiconductor encapsulations. 1, 2 However, epoxy resins, initiated by a curing agent, often become brittle due to the inherent properties, resulting from the high degree of crosslinking during the process of self-polymerization. Hence, modification of epoxy resins has been the subject of intensive interesting research. For this reason, the blends of DGEBA and epoxy resins with high thermal properties have been interesting field due to the potential improvement in thermal properties of DGEBA. In common epoxy/amine systems, there are some problems such as toxicity of amine, the deterioration of electrical properties at high temperature, humidity, and inherently brittle behaviors. In recent years, thus, the cationic polymerization of epoxide has been studied intensively. 3, 4 The cationic epoxy formulations have long-term stability at room temperature in the absence of light and cure rapidly when exposed to high temperature. Particularly, the cationic epoxy system can improve the deterioration of electrical properties, which results from the hydrophilic character of the amine functional group in the epoxy/amine system. In the cationic mechanism, the epoxy groups are opened by active proton (H+) that is replaceable by a metal to produce a new physicochemical bond or a hydroxyl group. This catalyst is generally used as a complex, such as BF3-ether, BF3-amine, or SbF6-epoxide. The complex overcomes the disadvantages of excessively rapid gelation, high hygroscopicity, and light instability. Particularly, the development of latent catalysts for cationic polymerization is desirable for the enhancement of both the pot life and handling of thermosetting resins. 5, 6 Usually, the latent catalyst forms active species by external stimulation such as heat and photoirradiation.The objective of this work is to study the effect of epoxy resin (EMPT) with high thermal properties on thermal stability of the DGEBA/EMPT system, initiated by cationic latent catalyst. The characterization of thermal stability for this system was monitored by thermogravimetric analysis (TGA). The epoxy resin used in this study was the diglycidyl ether of bisphenol A (DGEBA, YD-128, supplied from Kukdo Chem. Co. of Korea). Another epoxy resin used was m-phenylenediaminebis (1, 2, 3, 6-tetrahydro-3, 4-epoxyphthalimide)(EMPT) which was synthesized using m-phenylenediaminebis (1, 2, 3, 6-tetrahydro-3, 4-epoxyphthalimide)(7.52 g, 0.02 mol) as a diimide in the Hanyang University lab. 7 The crude product was recrystallized in CHCl3/ethyl alcohol (EA)(1/1) solution. Finally, the product was purified through column chromatography (70-230 mesh) using a CHCl3/EA (1/4) solution as an eluent. The color of the product was white, and the yield was 4.0 g (49%). The purity and the chemical structures of the product were confirmed by infrared (FT-IR) spectroscopy, 1H NMR, 13C NMR, and elemental analysis as follows. For FT-IR (KBr pellet): 3030 cm-1 (aromatic CH stretch), 1780 and 1710 cm-1 (imide CdO stretch), 1383 cm-1 (CN stretch), 950-810 cm-1 (asymmetrical stretch or epoxide). For 1H NMR (CDCl3): δ 7.6-7.4 ppm