短切聚酰亚胺纤维增强可瓷化三元乙丙橡胶复合材料的制备与性能

Preparation and properties of ceramifiable ethylene propylene diene monomer rubber composites reinforced with chopped polyimide fibers

以三元乙丙橡胶(EPDM)为基体,高岭土(Kaolin)和滑石粉(Talc)为功能填料,Al(OH)_3为阻燃剂,短切聚酰亚胺纤维(PI Fiber)为增强材料,制备了不同PI纤维含量的可瓷化PI Fiber-Kaolin-Talc-Al(OH)3/EPDM(PKTA/EPDM)复合材料。研究了短切PI纤维对复合材料拉伸性能、热稳定性和微观形貌的影响,分析了短切PI纤维增强复合材料的陶瓷化机制。研究表明,短切PI纤维含量增加会导致可瓷化PKTA/EPDM复合材料拉伸性能下降,当纤维含量与EPDM质量比低于10∶100时,复合材料力学性能良好。可瓷化PKTA/EPDM复合材料在800~1 100℃热解后均发生陶瓷化反应。当PI纤维与EPDM质量比为4∶100~8∶100时,可以有效保持复合材料高温热解后的形状尺寸稳定,并且热解产物弯曲强度在6~18 MPa之间。热分析结果表明,加入PI纤维可以提高可瓷化PKTA/EPDM复合材料的热稳定性。结合热分析和断面SEM分析表明,PI纤维热解、炭化后贯穿在EPDM裂解后的炭层中形成纤维增强炭层结构。这种纤维增强结构在复合材料热解过程中有助于获得尺寸稳定、形状完整的陶瓷产物。

The ceramifiable ethylene propylene diene monomer（EPDM）composites with different fiber contents were prepared by taking EPDM as the matrix,kaolin and talc as the functional fillers,aluminum hydroxide as the flame retardant,and the chopped polyimide（PI）fiber as the reinforcement.The effects of chopped polyimide fibers on the tensile properties,thermal stability and microstructure of ceramifiable PI fiber-Kaolin-Talc-Al（OH）_3/EPDM（PKTA/EPDM）composites were investigated,and the ceramicization mechanism of chopped polyimide fiber reinforced composites was analyzed.The results show that the tensile strength of the composites decreases with the increasing of the content of chopped polyimide fibers.When the chopped PI fibers are less than 10∶100（mass ratio to EPDM）,the mechanical properties of the composites are good.The ceramifiable PKTA/EPDM composites can be ceramicized after pyrolysis at 800-1 100℃.The addition of 4∶100-8∶100（mass ratio to EPDM）chopped polyimide fibers can effectively keep the shape stability of the composites after pyrolysis at 800-1 100℃,and the bending strength of the ceramic products is between 6-18 MPa.The results of thermal analysis show that the thermal stability of the composites can be improved by adding the chopped polyimide fibers.The results of thermal analysisand SEM analysis indicate that the pyrolysis and carbonization of the chopped PI fibers in the char layer form the structure of fiber-reinforced char layer.The PI fiber reinforced structure contributes to obtaining the well-shaped ceramic products in the pyrolysis of the PKTA/EPDM composites.