低收缩率聚丙烯改性料的制备研究

Preparation of Low Shrinkage Polypropylene Modified Materials

考察了不同类型聚丙烯(PP)的收缩率,研究了无机填料、增韧剂改性PP的性能及其收缩率变化情况。结果表明:不同类型PP的收缩率不同,均聚PP收缩率最大,无规共聚PP次之,抗冲共聚PP最小。当抗冲共聚PP中乙烯含量增加时,其收缩率降低。模塑试样放置0.5~5.0 h以内时,模具温度越高,收缩率越大;随着放置时间延长,PP收缩率继续增大,放置5.0 h以上时收缩率随时间延长变化不大。添加无机填料改性可以降低PP收缩率,与连续玻璃纤维(GF)和短切GF相比,滑石粉改性对降低PP收缩率更有效。聚烯烃弹性体(POE)和茂金属线型低密度聚乙烯(mLLDPE)具有较好的增韧作用;当滑石粉和mLLDPE质量分数分别为30.0%和15.0%时,采用进口抗冲共聚PP制备的复合材料刚韧综合性能良好,平行和垂直流道方向的收缩率均为0.50%。

The shrinkage rates of different types of polypropylene(PP)were investigated,and the properties and shrinkage changes of PP modified with inorganic fillers and toughening agents were studied.The results show that the shrinkage rates of different types of PP are different,homopolymer PP has the highest shrinkage rate,followed by random copolymer PP,and impact copolymer PP has the lowest shrinkage rate.When the ethylene content in impact copolymer PP increases,its shrinkage rate decreases.The higher the mold temperature,the greater the shrinkage rate when the molded sample is placed from 0.5 to 5.0 hours.As the placing time prolongs,the shrinkage rate continues to increase.The shrinkage rate does not change significantly when placed for more than 5.0 hours.Adding inorganic fillers for modification can reduce the shrinkage rate of PP,compared to continuous glass fiber(GF)and short cut GF,talc powder modification is more effective in reducing the shrinkage rate PP.Polyolefin elastomers(POE)and metallocene linear low density polyethylene(mLLDPE)have good toughening effects.When the mass fractions of talc powder and mLLDPE are 30.0%and 15.0%,respectively,the imported impact copolymer PP composite has good comprehensive stiffness and toughness properties,with shrinkage rates of 0.50%in both parallel and vertical flow directions.