Using simplex equation for predicting mechanical properties of polymer blends

Abstract

The objective of this research work is to study the use of Simplex equation for predicting mechanical properties of several kinds of polymer blends. In addition, polymer blend of polypropylene(PP) with four different molecular weights of high-density polyethylene(HDPE) will be prepared to study how the interaction parameter in Simplex equation depends on the molecular weight of HDPE in the blends. Mechanical properties as a function of composition, composed of modulus, tensile strength, impact strength and elongation at break of various blends, were searched and collected. About 89 from 120 sets of mechanical properties fir fairly well with experimental properties collected, although there are deviations in some systems especially in elongation and impact strength due to interfacial adhesion effect between phase. Molecular weight of four polyethylene are in the ranges of 38,000-102,000 while molecular weight of polypropylene equals to 122,00 approximately. HDPE-PP blends were prepared in a twin screw extruder. Their modulus and yield strength can be predicted by Simplex equation, and the interaction parameter tends to decline when the molecular weight of polyethylene decrease. From thermal analysis, degree of crystallinity directly affects the mechanical behavior of these blends.