Abstract:

A series of phthalonitrile/carbon fiber composites were prepared using short⁃cut carbon fibers as a reinforcement agent， and the effects of the content and length of short⁃cut carbon fibers and the type of coupling agent on the mechanical properties of the composites were investigated using a universal testing machine and a dynamic thermomechanical analyzer. The results indicated that the composites obtained optimal mechanical properties and thermal stability when phenyltriethoxysilane was used as a coupling agent. Compared to the composites without a coupling agent， the composites modified with phenyltriethoxysilane exhibited an increase in the energy storage modulus by 22.2 % and in the characteristic temperature at a 5 wt% weight loss by 33.1 %. With an increase in the addition amount of carbon fibers， the mechanical properties of the composites showed an increasing trend at first and then tended to decrease. The composites obtain optimal mechanical properties at a carbon⁃fiber loading of 0.3 wt%. Compared to pure phthalonitrile resin， the composites achieved an increase in bending strength by 38.4 % and in bending modulus by 97.7 %. The composites exhibited higher bending strength and a higher energy⁃storage modulus at a carbon⁃fiber length of 6 mm than those at a fiber length of 3 mm.

Key words: phthalonitrile, carbon fiber, composite, dynamic mechanical property, mechanical property