本文提供了证据,并讨论了未添加其他成分的原始和再生聚丙烯/高密度聚乙烯共混物的热机械行为的可变性,这在文献中是稀疏的。了解再生聚合物共混物的性能可变性对于促进再生材料重新进入消费市场至关重要,因此,为循环经济做出贡献。由于回收材料的不均匀性,这是一个需要进一步研究的领域。因此,系统研究了原始和再生聚丙烯/高密度聚乙烯共混物的热性能和力学性能。差示扫描量热法得出的结论是,回收和原始共混物都是不混溶的。一般来说,与原始共混物相比,回收共混物具有较低的整体结晶度和熔融温度,值得注意的是,它们的结晶温度比较有利。动态力学分析表明,回收和原始混合物的储能模量几乎没有变化。然而,由于结构劣化,再生共混物的α和β弛豫温度较低。回收共混物的热和机械性能的恶化被认为是由污染物的存在和再加工过程中的结构降解引起的。导致较短的聚合物链和不完美的微晶的形成。回收共混物的拉伸性能也受回收过程的影响。由于回收过程中的劣化,回收共混物的杨氏模量和屈服强度劣于原始共混物。然而,与原始共混物相比,回收共混物的断裂伸长率更高,可能是由于低分子量链片段的可塑性作用。
This paper provides evidence and discusses the variability in the thermomechanical behaviour of virgin and
recycled polypropylene/high-density polyethylene blends without the addition of other components, which is sparse in the literature. Understanding the performance variability in
recycled polymer blends is of critical importance in order to facilitate the re-entering of recycled materials to the consumer market and, thus, contribute towards a circular economy. This is an area that requires further research due to the inhomogeneity of
recycled materials. Therefore, the thermal and mechanical properties of virgin and recycled polypropylene/high-density polyethylene blends were investigated systematically. Differential scanning calorimetry concludes that both the
recycled and virgin blends are immiscible. Generally, recycled blends have lower overall crystallinity and melting temperatures compared with virgin blends while, remarkably, their crystallisation temperatures are compared favourably. Dynamical mechanical analysis showed little variation in the storage modulus of recycled and virgin blends. However, the alpha and beta relaxation temperatures are lower in recycled blends due to structural deterioration. Deterioration in the thermal and mechanical properties of recycled blends is thought to be caused by the presence of contaminants and structural degradation during reprocessing, resulting in shorter polymeric chains and the formation of imperfect crystallites. The tensile properties of
recycled blends are also affected by the recycling process. The Young\'s modulus and yield strength of the recycled blends are inferior to those of virgin blends due to the deterioration during the recycling process. However, the elongation at break of the recycled blends is higher compared with the virgin blends, possibly due to the plasticity effect of the low-molecular-weight chain fragments.