共混物对二次发泡聚丙烯的发泡效果和力学性能的影响

运用型内二次发泡工艺确定了低密度聚乙烯(LDPE)或高熔体强度聚丙烯(HM SPP)共混改性发泡聚丙烯(PP)的配方,用傅里叶红外光谱仪和扫描电镜研究了共混聚合物组分的种类和含量对PP分子结构、泡孔结构的影响机制及断口形貌,共混聚丙烯发泡材料的发泡效果和力学性能的影响规律。结果表明,在共混过程中,部分PP和LDPE分子在热的作用下相互促进,产生了接枝交联;共混物比纯PP的泡孔结构优且发泡效果佳,其中LDPE的用量范围比HM SPP更宽,且含LDPE为30%时聚丙烯的发泡效果最好;HM SPP的发泡体的抗弯强度明显要高于LDPE;而LDPE对发泡体冲击强度的影响要显著大于HM SPP。

Effect of Co-blend Polymers on Foamed Result and Mechanical Properties of Secondary-Foamed Polypropylene

The formula of polypropylene(PP) foam co-blend modified with low density polyethylene(LDPE) or high melt strength(PP)(HMSPP) by the co-blend method is determined via a secondary-foaming process in the design of dies(post-foaming).The influence of the species and the content of co-blend polymers on the molecular structure of PP,pore microstructure and density,the fracture appearance and mechanical properties of PP foams are explored by FTIR and SEM.Results show that in the coblend process,thermal effect promotes grafting cross-linking between partial PP and LDPE molecules.Moreover,the co-blend foamed by PPs exhibit finer pore configuration and better foaming effect than pure PP,in which the dosage range of LDPE is wider than that of HMSPP,and foaming effect of PP with 30%(mass percent) LDPE is the best.Additionally,the bend strength of the foaming PP co-blended with HMSPP is obviously high than that of the foaming PP co-blended with LDPE.However,compared with HMSPP,LDPE has a prominent effect on the impact strength.