甲基丙烯酸/丙烯腈(MAA/AN)共聚物泡沫制备过程中的“原位成环”反应研究

Research on In-situ Cyclization Reaction in the Preparation of MAA/AN Copolymer Foam

以甲基丙烯酸(MAA)和丙烯腈(AN)为原料,通过自由基本体聚合制备了一种硬质MAA/AN共聚物泡沫。探讨了相应共聚物在发泡和热处理过程中发生的“原位成环”反应及机理,并利用差示扫描量热分析(DSC)和红外光谱(FTIR)进行了验证。结果表明：MAA/AN共聚物的DSC．曲线在179．57℃有酸酐化放热反应峰。发泡和热处理以后,MAA/AN共聚物FTIR谱图中的羧羟基—OH弯曲振动峰减弱,而酸酐C—O—C伸缩振动峰加强,且出现了酸酐＞C=O的伸缩振动峰；生成了较为强烈的＞C—N弯曲振动峰；—C≡N伸缩振动吸收峰略微减弱,并出现了新的—C=N—吸收谱带。说明分子链上发生了“原位成环”反应,形成的刚性酸酐环、六元酰亚胺环以及梯形结构使MAA/AN共聚物泡沫具有高闭孔率和优异的力学、耐热性能。

Methacylic acid/acrylonitrile （MAA/AN） copolymer foam was prepared via the means of radical bulk polymerization. The mechanism of in-situ cyclization during the foaming and heat treatment was studied using differential scanning calorimeter （DSC） and Fourier transform infrared spectrometer （FTIR）. There was exothermic peak at 179.57℃; in the DSC curve of MAA/AN copolymer indicating the anhydride formation. After foaming and heat treatment, -OH bending vibrant peak of carboxyl weakened, while C-O-C stretching vibrant peak of anhydride strengthened, and 〉 C=O stretching vibrant peak of anhydride and a stronger bending vibrant peak of 〉 C-N appeared. The stretching vibrant peak of --C≡N weakened slightly, while a new absorbing of -C=N- appeared. All these features indicated that the in-situ cyclization took place during the foaming and heat treatment. Such anhydride and hexahydric imide rings as well as trapeziform structure resulted in a high closed-cell ratio, excellent mechanical and heat-resistant properties.