Polypropylene (PP) and low-density polyethylene (LDPE) are among the most converted resins; as such, they also have the largest share in municipal waste fractions. Currently, there is a great societal and industrial need to recycle these polymers using thermo-mechanical processes. However, process-induced degradation during recycling operations may lead to irreversible changes. In this study, PP was blended with 0 to 10 wt.% of LDPE was subjected to consecutive twin-screw extrusion cycles (0 to 5 times) to mimic thermo-mechanical recycling. The effect of reprocessing on the rheological, thermal, and mechanical properties of PP/LDPE blends was investigated. An increase in MFR and decrease in viscosity was observed for PP and the blends. DSC results showed that the crystal structure of PP was seriously affected and generated more disorder with reprocessing. Although tensile properties were not substantially affected, all properties had a decreasing trend. While successive thermo-mechanical processing caused chain scission of the PP phase of the blend, the overall property of the studied blend composition maintained acceptable properties. Thus, recycling of PP with low PE blend additive is a feasible option not only to reduce plastic waste but also to generate value from an otherwise waste product.

聚丙烯（PP）和低密度聚乙烯（LDPE）是转化率最高的树脂。因此，它们在城市垃圾中所占份额也最大。当前，社会和工业上都需要使用热机械方法来回收这些聚合物。但是，回收操作过程中由过程引起的性能下降可能导致不可逆的变化。在这项研究中，将PP与0至10 wt％的LDPE混合，进行连续的双螺杆挤出循环（0至5次）以模拟热机械循环。研究了后处理对PP / LDPE共混物流变，热学和机械性能的影响。对于PP和共混物，观察到MFR增加和粘度降低。DSC结果表明，PP的晶体结构受到严重影响，并且随着后处理而产生更多的无序。尽管拉伸性能基本上没有受到影响，但是所有性能都有下降的趋势。虽然连续的热机械加工导致共混物的PP相断链，但研究的共混物组合物的整体性能仍保持可接受的性能。因此，用低PE掺混添加剂回收PP是一种可行的选择，不仅可以减少塑料浪费，而且可以从其他废品中创造价值。研究的共混物组合物的总体性能保持可接受的性能。因此，用低PE掺混添加剂回收PP是一种可行的选择，不仅可以减少塑料浪费，而且可以从其他废品中创造价值。研究的共混物组合物的总体性能保持可接受的性能。因此，用低PE掺混添加剂回收PP是一种可行的选择，不仅可以减少塑料浪费，而且可以从其他废品中创造价值。