玻璃微球填充聚丙烯的流变行为

为了阐明聚丙烯(PP)/玻璃微球(GM)体系的流变性质特点,采用不同含量的GM对PP进行填充改性,通过双辊混炼法制备了PP/GM体系,利用流变仪测试了PP/GM体系的流变行为,采用管长判别法进行毛细管入口修正,讨论了GM含量、剪切应力、温度等参数对PP/GM体系流变行为的影响,分析探索各参数对熔体表观黏度的影响规律。结果表明,采用管长判别法进行入口修正可大幅减少实验工作量,且合适的毛细管长径比是保证管长判别法精度的关键。PP/GM体系属非牛顿假塑性熔体,可用幂律公式表达;随GM含量增加,PP/GM体系黏度增加、非牛顿性减弱。温度越低,黏度随GM含量增加而升高的速率越高;剪切应力越大,黏度随温度升高而下降的速率越低。基于正交多项式的回归分析方法,从实验数据推导表观黏度与GM含量、剪切应力、温度之间的函数关系式,其表观黏度对数计算值与实测值非常接近,能较准确地反映实际流变行为,指导PP/GM体系的实际加工生产应用。

Rheological Behavior of Glass Microsphere Filled Polypropylene

In order to expound the characteristics of rheological properties of polypropylene (PP)/glass microsphere (GM) system,GM with different contents filled PP (PP/GM) systems were prepared by double roller mixing. The rheological properties of PP/GM were tested by rheometer and tube length determination method was used for the amendment of capillary tube inlet. The effects of GM content,shear stress,and temperature on the rheological behaviors of PP/GM were investigated. The influential laws of these parameters on the melting apparent viscosity of PP/GM were analyzed and explored. The results indicate that,the inlet amendment by the tube length determination method can significantly reduce the amount of experiments,and the suitable aspect ratio of capillary tube is key to ensure accuracy of the method. The melts of PP/GM composites display the behavior of non-Newtonian pseudoplastic flow,the relation between shear stress and shear rate can be expressed as the power-law model. With the increase of the GM content,the viscosity of PP/GM increases and the non-Newtonian behavior weakens. The lower the temperature is,the higher the increasing rate of viscosity with the GM content increasing is,the higher the shear stress is,the lower the decreasing rate of viscosity with the temperature increasing is. Based on orthogonal polynomial regression method,the regression equation from the experimental data as a function of the apparent viscosity with the GM content,shear stress,and temperature is derived ,the calculat-ing values of the apparent viscosity logarithm are closed to the testing values,which shows that the regression equation can accu-rately express the actual rheological behavior and guide the actual processing production of PP/GM system.