含苯并咪唑结构双马来酰亚胺的合成与表征

Synthesis and characterization of bismaleimide containing benzimidazole structure

针对结构复合材料高耐温等级的应用需求,从改善双马来酰亚胺(BMI)树脂基体性能出发,采用分子设计的方法,将刚性苯并咪唑环结构引入单体主链中,以共沸甲苯法合成出含单苯并咪唑结构双马来酰亚胺单体(BZ-BMI)和含邻苯并咪唑结构双马来酰亚胺单体(OBZ-BMI)。采用核磁共振氢谱与傅里叶变换红外(FTIR)光谱对中间产物和目标产物的结构进行表征。采用差示扫描量热(DSC)法和热重(TG)分析法研究了单体的固化行为及固化物的热稳定性。DSC曲线结果表明,BZ-BMI与OBZ-BMI在210~370℃温度范围内进行交联固化,其固化行为受链段长度、分子结构规整性与相互作用力影响较大;同时,结合DSC曲线确定了单体的固化工艺为200℃/2 h+250℃/2 h+330℃/6 h;FTIR分析表明此工艺可以完全固化。TG分析表明,其热分解温度与二苯甲烷型双马来酰亚胺(BDM)相当,而P(BZ-BMI)与P(OBZ-BMI)在800℃下残炭率分别为74.7%与70.4%,远高于P(BDM)的测试值(48.3%),说明苯并咪唑结构的引入有效提高了BMI的耐热阻燃性能;OBZ-BMI共聚改性体系保持了优异的力学性能,较传统二烯丙基双酚A改性BMI体系的冲击强度提高了20%,拓宽了BMI在耐高温树脂基结构复材领域的应用范围。

Aiming at the application requirements of high temperature resistance of structural composites,in order to improve the properties of bismaleimide(BMI)resin matrix,the rigid benzimidazole ring structure was introduced into the main chain of the monomer by molecular design method,and the bismaleimide monomer containing single benzimidazole structure(BZ-BMI)and bismaleimide monomer containing o-benzimidazole structure(OBZ-BMI)were synthesized by azeotropic toluene method.The structure of the intermediate product and the target product was characterized by nuclear magnetic resonance spectroscopy(1H-NMR)and Fourier transform infrared spectroscopy(FTIR).The curing behavior of the monomer and the thermal stability of the cured product were studied by differential scanning calorimetry(DSC)and thermogravimetric(TG)analysis.The results of DSC curves show that BZ-BMI and OBZ-BMI are crosslinked and cured in the temperature range of 210-370℃,and the curing behavior is greatly affected by the length of the segment,the regularity of the molecular structure and the interaction force.At the same time,combined with the DSC curve,the curing process of the monomer is determined to be 200℃/2 h+250℃/2 h+330℃/6 h.FTIR analysis shows that this process can be completely cured.The results of TGA shows that the thermal decomposition temperature of P(BZ-BMI)and P(OBZ-BMI)are comparable to that of diphenylmethane bismaleimide(BDM),while the residual carbon rates of P(BZ-BMI)and P(OBZ-BMI)at 800℃are 74.7%and 70.4%,respectively,which are much higher than the test value of P(BDM)(48.3%),indicating that the introduction of benzimidazole structure effectively improves the thermal flame retardancy.The OBZ-BMI copolymerization modification system maintains excellent mechanical properties,and the impact strength is 20%higher than that of the traditional diallyl bisphenol A modified BMI system,which broadens the application range of bismaleimide in the field of high temperature resistant resin-based structural composites.