目的 随着全球“双碳”目标的持续推进，塑料回收再利用越来越深入，研究塑料在回收过程中性能的衰减规律，对提升塑料回收效果具有重要的实践指导作用。方法 采用多次反复混炼挤出加工方法对聚苯乙烯及其稻壳填充复合材料进行处理，重点研究热加工次数对复合材料力学性能及加工性能的影响，并对复合材料性能衰减的机理进行分析探讨。结果 回收过程中重复热加工会显著降低聚苯乙烯及稻壳填充聚苯乙烯复合材料的拉伸强度、冲击强度、维卡软化温度与模塑收缩率，其中纯聚苯乙烯的性能保持率与热加工次数呈显著线性关系。经历4次热加工后聚苯乙烯的拉伸强度与冲击强度分别下降了14.35%与14.55%，复合材料的拉伸强度与冲击强度的下降幅度最大，分别达到14.55%与20.01%。稻壳的加入可以减缓热加工次数对复合材料性能衰减速率的影响，多次热加工会提升复合材料的熔融指数。结论 多次重复热加工对聚苯乙烯及其稻壳填充复合材料力学性能保持率的影响较大，呈近线性关系。抗氧剂的使用可以显著降低复合材料力学性能的衰减速率，本研究可以为该类复合材料的配方与加工工艺优化提供理论指导。

With the rapid development of global "dual-carbon" (carbon peaking and carbon neutrality), the recycling of plastic gets deeper and deeper. The study of the performance attenuation law of plastics in the recycling process has an important practical guiding role in improving the recycling effect of plastics. The repeat extrusion method was used to prepared recycled polystyrene and rice husk filled composites. The effects of thermal processing cycles on mechanical properties and processing performance, as well as their performance attenuation mechanism were investigated. The results showed that repeat thermal processing could obviously reduce the tensile strength, impact strength, vicat softening temperature, and mould shrinkage of polystyrene and rice husk filled composites during the recycling processing. There was a significant linear relationship between the retention rate of pure polystyrene and the thermal processing cycles. The tensile and impact strength of pure polystyrene decreased by 14.35% and 14.55%, respectively after four thermal processing cycles. Among which, the tensile and impact strength of rice husk filled polystyrene composite decreased the most, by 14.55% and 20.01%, respectively. The addition of rice husk could decrease the attenuation rate of comprehensive performance of composites. Repeat thermal processing could improve the melt flow index for both the pure and filled composites. Repeated thermal processing has great effects on the mechanical properties of polystyrene and its rice husk filled composites, there is a relative linear relationship between them. Antioxidant can reduce the decay rate of the mechanical properties of composites. The insights obtained from this investigation can offer valuable and theoretical references for optimization of formulas and processing parameters of such related composites.