The presence of a polyethylene (PE) fraction in recycled polypropylene (PP) will influence the processing as well as mechanical and thermal properties of recycled polypropylene. The objective of this work has been to compare methods used to determine the fraction of PE in recycled PP, establishing calibration curves for each method. Plastics waste will be a mix of different grades – homopolymers and copolymers. It has therefore been tested how specific material grades affect the results. Characterization methods used were differential scanning calorimetry (DSC), FT-IR spectroscopy, NMR, and gel content measurement after peroxide extrusion. We have applied the derived calibration curves for two different post-consumer, recycled PP (rPP) in addition to a known 50/50 blend of PE and PP. DSC, NMR, FT-IR and gel content give quite consistent estimates of the PE content.

回收聚丙烯（PP）中聚乙烯（PE）组分的存在将影响回收聚丙烯的加工以及机械和热性能。这项工作的目的是比较用于确定再生PP中PE含量的方法，并为每种方法建立校准曲线。塑料废料将是不同等级的混合物-均聚物和共聚物。因此，已经测试了特定材料等级如何影响结果。使用的表征方法是差示扫描量热法（DSC），FT-IR光谱，NMR和过氧化物挤出后的凝胶含量测量。除了已知的PE和PP混合物50/50外，我们还应用了两种不同的消费后回收PP（rPP）的导出校准曲线。DSC，NMR，