挤出循环对玻纤增强PA66复合材料流变性能和力学性能的影响

通过双螺杆挤出机对w=35%玻纤增强尼龙66（PA66/GF35）复合材料进行循环加工，研究了挤出循环次数对PA66/GF35的流变性能、热性能、玻纤长度和力学性能的影响。结果表明：随挤出循环次数的增加，PA66/GF35复合材料的熔体体积流动速率逐渐增加，表观黏度显著下降；多次挤出加工使PA66基体发生热氧降解，特性黏度逐渐减小，熔点、结晶温度、结晶度略有降低；玻纤断裂，玻纤保留长度变短。PA66/GF35复合材料的力学性能随挤出循环次数的增加逐渐下降，经4次挤出循环后其拉伸强度、弯曲模量和冲击强度分别下降了38.41%、21.73%和67.33%。

Influence of Extrusion Cycle on the Rheological and Mechanical Properties of Glass Fiber Reinforced PA66 Composites

Glass fiber reinforced PA66 (PA66/GF35) composites were reprocessed by the twin screw extruder.The effects of extrusion cycles on the rheological properties,thermal performance,glass fiber length and mechanical properties were investigated.The results showed that the melt volume flow rate of PA66/GF35 composites increased gradually and their apparent viscosity decreased significantly upon increasing the number of reprocessing cycle.For PA66 matrix,thermal oxidative degradation occurred during extrusion cycles,which led to the decrease of the intrinsic viscosity,the melting point,crystallization temperature and the degree of crystallinity,as well as the fraction of glass fiber and reduction of glass fiber length.Mechanical properties of PA66/GF35 composites were weakened with the increase of extrusion cycle.After four cycles extrusion,their tensile strength,flexural modulus and impact strength reduced by 38.41%,21.73% and 67.33%,respectively.