苯并噁嗪/氰酸酯共聚体的结构与性能

Structures and Properties of Benzoxazine/Cyanate Ester Copolymer

以双酚A型苯并噁嗪(Ba)与双酚A型氰酸酯(BADCy)为原料,系统研究了苯并噁嗪/氰酸酯共混体系的固化过程及共聚体结构与性能的关系。结果表明,固化过程依次发生:(1)部分Ba开环后催化BADCy的聚合反应;(2)Ba的自聚反应。Ba与BADCy通过共聚反应,最终形成含有三嗪环结构的聚苯并噁嗪交联体系。动态力学分析表明,随着氰酸酯比例的增加,共聚体中的氢键减少,初始模量逐渐降低,但生成的三嗪环增多,Tg上升,共聚体的模量保留率增高。热失重分析显示,共聚体在低温没有出现明显的失重速率峰,5%和10%的失重温度以及800℃的残炭率都高于聚苯并噁嗪,且氰酸酯比例越高,热稳定性越好。力学测试表明,共聚体的弯曲性能略有下降,但冲击性能显著提高。共聚体在不同的电场频率下均保持了较低的介电常数和介电损耗。但共聚体中氢键作用减弱,导致吸水率增加。

The studies on the curing process of Ba / BADCy system show that there are two main reactions：（ 1） the polymerization of cyanate ester catalyzed by the ring-opened benzoxazine and（ 2） the self-polymerization of benzoxazine.Finally,a co-reacted network composed of triazine ring as a part of polybenzoxazine matrix is formed. With increase of cyanate ester content,initial modulus of the copolymer decreases,due to reduction of the number of hydrogen bonds.However,the Tgof the copolymer increases with generation of stable and rigid triazine ring. The copolymers exhibit better thermal stabilities than polybenzoxazine with higher Td5,Td10 and char yield. The flexural properties of the copolymer are decreased slightly,and the impact strength is significantly improved. At different electric field frequencies,the copolymers demonstrate low dielectric constant and dielectric loss factor. But the hydrogen bond interaction of the copolymer is decreased,resulting in increased water absorption.