通过熔融共混法采用均聚聚丙烯(PP-H)和嵌段共聚聚丙烯(PP-B)制备了PP微发泡基础树脂,并研究了pp-H用量对基体树脂发泡后力学性能的影响;同时采用发泡改性剂和成核剂(碳酸钙、滑石粉)对PP微发泡基础树脂进行改性,研究了发泡改性剂和成核剂用量对PP发泡性能的影响.结果表明,随PP-H用量的增加,发泡片材的拉伸强度下降,弯曲强度增加;发泡改性剂提高了PP的熔体强度,随成核剂碳酸钙、滑石粉用量的增加,发泡片材的密度下降,泡孔密度增大,其适宜用量为0.5份(质量份,下同);改性后PP的剪切黏度变小,挤出胀大比增大,相对分子质量分布变化不大;用改性PP制备的微发泡片材的泡孔直径小于50 μm,泡孔密度可达106个/cm3.%Expandable polypropylene (PP)-based resin was prepared for microfoam sheets by using homopolypropylene (PP-H) and block-copolymerized polypropylene (PP-B) through a meltblending method,and effects of PP-H content on mechanical properties of microfoam sheets were investigated.In addition,foaming modifier and nucleating agents (calcium carbonate and talcum powder) were used to modify microfoaming behavior of PP resin,and effects of contents of foaming modifier and nucleating agents on foaming behavior of PP were also studied.The results indicated that the tensile strength of microfoam sheets decreased but their flexural strength increased with an increase of PP-H content.The foaming modifier improved the melt strength of PP.The density of microfoam sheets decreased but their cell density increased with increasing contents of nucleating agents.As an appropriate amount,0.5 phr of nucleating agent was recommended for the microfoam sheets.The modified PP exhibited an increase in shear viscosity and extrusion expansion ratio,and however,its molecular weight distribution almost did not changed.These microfoam sheets were found to have a cell diameter less than 50 μm and a cell density up to 106 cell/cms.
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