Study On Rheology Mechanism And Rheological Behavior Of HDPE/EVA Blend

Polymer blend is a kind of composite system that consists of polymer materials of two or more than two kinds. It can improve the properties of original polymer materials, or form new ones with new properties. Polymer blend has formed a new and important subject of polymer material science and engineering fields. Rheological behavior is the most important processability of polymer blend, because in the machining and forming process of most polymer materials, the rheological behavior in viscous flow state is absolutely necessary. But in order to achieve the required property, we must reasonably design materials compounding. With the change of matrix material and polymer ratio, the system processability will change accordingly, and finally resulting in the change of the mechanical property of the products. In order to reasonably guide material formulas and optimize the polymer blend processability, we must strengthen the study of rheological behavior of polymer blend.Based on the summarization of a number of equations describing rheological behavior of polymer blend, Heitmiller equation which describes the rheological behaviors relationship between matrix and matrix constitute was corrected, and made accord with practice better. The effect of shear rate on polymer blend rheological behavior was linked with the effect of temperature and polymer fraction together respectively. A system method was devised to forecast the viscosity of the polymer blend in a number of different conditions only through several groups of rheology tests.Numerous rheological tests of polymer blend with high density polyethylene and ethylene/vinyl acetate of different ratios at different temperatures were done in the Rosand RH7D double dies capillary rheolometer to evaluate the rheology equations. Through the experiments, the correctness of the theoretical model was verified; the special values of the parameter presented in the theory mold were obtained. The effect of different ratios on viscosity of polymer blend was studied. Aiming at melt fracture phenomena in extrusion process, the change law of pressure oscillation of polymer blend of different ratios was studied.