聚丙烯/聚乙烯共混物的粘弹性及其对挤出发泡的影响

以聚丙烯（PP）与4种聚乙烯（低密度聚乙烯（LDPE）、线性低密度聚乙烯（LLDPE）、高密度聚乙烯（HDPE）、热塑性弹性体（TPE））共混物作为原料，采用超临界二氧化碳作为发泡剂，在同向双螺杆挤出机-熔体泵发泡系统上进行挤出发泡实验。同时，运用旋转流变仪测试了LDPE、LLDPE、HDPE、TPE与PP共混对其流变性能的影响。结果表明，HDPE/PP、TPE/PP共混体系的储能模量较大、零切黏度较大，使用这两种发泡体系可以得到泡孔尺寸小、泡孔均匀性好的发泡制品，且制品泡孔致密，泡孔破裂及合并现象较少。

The effect of polypropylene/polyethylene (PP/PE) blends viscoelasticity on PP foaming

The effect of four different kinds of polyethylene (PE)—low-density polyethylene (LDPE), linear low density polyethylene (LLDPE), high-density polyethylene (HDPE) and thermoplastic elastomer (TPE)—on polypropylene (PP) foaming has been analyzed based on a large number of PP foaming experiments carried out using a self-designed supercritical liquid foaming apparatus, four kinds of PP/PE blends as a matrix and supercritical carbon dioxide (SCCO₂) as the foaming agent. The rheological behavior of the PP/PE blends was investigated with a rheometer. The results showed that the storage modulus and viscosity of the HDPE/PP and TPE/PP blends were higher than the corresponding values for the LDPE/PP and LLDPE/PP blends, which gave the benefits of reduced cell rupture and coalescence, thus affording higher quality products.