Abstract: The non-Newtonian rheological properties of plastic melts are key factors in regulating plastic processing, molding and recycling processes, ensuring processing stability and product performance, and are the research focus in the field of plastic processing. The rheological basic data of commonly used plastics and their blend systems at present still need to be supplemented and improved. For this purpose, this study adopted a combined approach of experimental testing and theoretical modeling to investigate the rheological behaviors of four types of plastics, namely polypropylene (PP), polyethylene (PE), polystyrene (PS), and acrylonitrile-butadiene-styrene copolymer (ABS), as well as three binary blend systems of PE/ABS, PP/ABS, and PS/ABS. Rheological tests were conducted using a rheometer within the shear rate range of 0.1 s-1 to 100 s-1 and the temperature range of 180℃ to 250℃. The results indicated that the flow behavior index n of all samples was less than 1, and the apparent viscosity decreased significantly with the increase in shear rate, showing a clear shear thinning effect. Meanwhile, the consistency coefficient K changed with temperature in accordance with the Arrhenius relationship, and the melt viscosity decreased with the increase in temperature. This study quantitatively characterized the relationship between the mass fraction m (0.5<m≤1) of the main component in the binary blend systems and the melt viscosity. Based on the experimental data, a component correction term was introduced into the traditional power-law model to construct a constitutive equation that can simultaneously describe the effects of shear rate, temperature, and component fraction on melt viscosity. The average relative error between the model predictions and experimental values was only 5.90%. The rheological basic data and the modified constitutive equation obtained in this study can provide important theoretical support and data reference for the optimization of process parameters in fields such as waste plastic recycling and injection molding.

Key words: non-Newtonian fluid, rheological properties, viscosity-temperature model, plastic melt

摘要： 塑料熔体的非牛顿流变性能是调控塑料加工成型与回收工艺、保障加工稳定性及产品使用性能的关键因素，为塑料加工领域的研究重点。当前常用塑料及其共混体系的流变基础数据仍有待补充和完善。为此，本研究采用实验测试与理论建模相结合的方法，对聚丙烯(PP)、聚乙烯(PE)、聚苯乙烯(PS)和丙烯腈-丁二烯-苯乙烯共聚物(ABS)四种塑料以及PE/ABS, PP/ABS, PS/ABS三种二元混合体系的流变特性进行了研究。利用流变仪在剪切速率0.1~100 s-1、温度180~250℃区间内开展测试，结果表明，所有试样的流动行为指数n均小于1，表观黏度随剪切速率升高显著降低，表现出明显的剪切稀化效应；同时，稠度系数K随温度的变化符合Arrhenius关系，熔体黏度随温度升高而降低。本研究定量表征了二元混合体系中主要组分的质量占比m (0.5<m≤1)与熔体黏度的关系，并依托实验数据，在传统幂律模型中引入组分修正项，构建了可同时描述剪切速率、温度及组分占比对熔体黏度影响的本构方程，模型预测值与实验值的平均相对误差仅为5.90%。研究所得的流变基础数据及修正本构方程，可为废塑料回收利用、注塑成型等领域的工艺参数优化提供重要理论支撑与数据参考。

关键词: 非牛顿流体, 流变特性, 黏温模型, 塑料熔体