微孔发泡PP/OBC/滑石粉复合材料的泡孔结构和力学性能

The Cell Structure and Mechanical Properties of Microcellular Foaming PP/OBC/Talc Composites

采用超临界N发泡技术和注射成型工艺制备了微孔发泡聚丙烯(PP)/乙烯-辛烯嵌段共聚物(OBC)/滑石粉复合材料,研究了OBC的含量对PP/OBC/滑石粉复合材料泡孔结构和力学性能的影响。使用差示扫描量热仪、扫描电子显微镜分别对复合材料的结晶行为和泡孔结构进行表征。结果表明,少量OBC能改善PP/OBC/滑石粉复合材料的结晶行为和泡孔结构。当OBC质量分数为10%时,PP/OBC/滑石粉复合材料的泡孔密度为2.0×10^(6)个/cm^(3),平均泡孔直径为57μm。OBC具有良好的增韧效果,但会导致拉伸强度下降。当OBC的质量分数为20%时,PP/OBC/滑石粉复合材料缺口冲击强度高达79.7 kJ/m^(2),比未添加OBC时高了149.6%。当OBC质量分数高于20%时,PP/OBC/滑石粉复合材料的拉伸断裂方式会从脆性断裂转变为韧性断裂。当OBC质量分数为30%~40%时,PP/OBC/滑石粉复合材料断裂伸长率高达501.84%~554.63%。

The microcellular foaming polypropylene(PP)/olefin block copolymer(OBC)/talc composites were prepared by injection molding with supercritical Nfoaming technology.The effect of OBC contents on the cell structure and mechanical properties of PP/OBC/talc composites was studied.The crystallization behavior and cell structure were characterized by differential scanning calorimetry and scanning electron microscope.The result shows that OBC can improve the crystallization behavior and cell structure of PP/OBC/talc composites with a low OBC contents.When the mass fraction of OBC is 10%,the cell density and average cell diameter of the PP/OBC/talc composites are, respectively, 2.0×10^(6)/cm^(3) and 57 μm.The OBC shows a good toughening performance on the composites, however, it reduces the tensile strength.When the mass fraction of OBC is 20%,the impact toughness strength of PP/OBC/talc composites could reach 79.7 kJ/m^(2),which is 149.6%higher than that without OBC.When the mass fraction of OBC exceeds 20%,the tensile fracture mode of PP/OBC/talc composites could change from brittle fracture to ductile fracture.When the mass fraction of OBC is 30%~40%,the elongation at break of the PP/OBC/talc composites could reach 501.84%~554.63%.