高流动性聚丙烯的流变性能及热性能研究

Study on rheological properties and thermal properties of high-fluidity polypropylene

采用二叔丁基过氧化物(DTBP)对聚丙烯(PP)进行共混改性制备高流动性PP,借助转矩流变仪、差式扫描量热仪、热重/差热综合分析仪,研究DTBP添加量对PP的流变性能、热稳定性及结晶行为的影响。结果表明:在相同温度下,不同DTBP添加量的PP的表观黏度均随着剪切速率的增加而降低,呈现出剪切变稀的行为,是典型的非牛顿假塑性流体;随着DTBP添加量的增加,PP的表观黏度不断降低,PP熔体的流动性大幅度提高;随着DTBP添加量的增加,PP的热稳定性呈现先下降后上升的趋势,并在DTBP质量分数为0.7%时达到最低;随着DTBP添加量的增加,PP的熔融温度降低、结晶温度升高、结晶度呈现先下降后上升的趋势,且在DTBP质量分数为0.7%时结晶度达到最低,为33.11%;当添加DTBP质量分数为0.7%时,PP的降解效果最佳,可提高PP熔融纺丝的连续性。

High-fluidity polypropylene(PP)was prepared by blend modifying PP with di-tert-butyl peroxide(DTBP).The effects of DTBP addition on the rheological properties,thermal stability and crystallization behavior of PP were studied with torque rheometer,differential scanning calorimeter and thermogravimetric/differential thermal analyzer.The results showed that the apparent viscosity of PP with different DTBP addition decreased with the increase of shear rate at the same temperature,which was the shear thinning behavior of a typical non-Newtonian pseudoplastic fluid;the apparent viscosity of PP continuously decreased and the fluidity of PP melt increased significantly with the increase of DTBP addition;the thermal stability of PP first decreased and then increased with the DTBP addition,and reached the minimum value when the mass fraction of DTBP was 0.7%;the melting temperature of PP decreased,the crystallization temperature increased,and the crystallinity also decreased first and then increased with the DTBP addition,and the crystallinity reached the minimum value of 33.11%when the DTBP mass fraction was 0.7%;and the degradation effect of PP was optimized when the mass fraction of DTBP was 0.7%,which could improve the continuity of PP melt spinning process.