On the Correlation of Mechanical Properties of High Impact Polystyrene with its Morphology, Molecular-Weight Characteristics and Extrusion Conditions

Mechanical properties as well as practical ones of high impact polystyrene (HIPS) are defined by a number of parameters, characterizing its molecular and supermolecular structure: molecular weight (MW) and molecular weight distribution (MWD) of the polystyrene matrix, quantity, composition and structure of graft copolymer, dispersed and continuous phases volume ratio, rubber particles size, their substructure, etc. There are a number of papers (1-7) in which attempts have been made to study the effect of the most substantial factors on polymer properties in order to find their optimal combination. This task concerning HIPS and ABS plastics is not simple for it is difficult to prepare polymers with a definite value of one given parameter, keeping the others constant. In addition, it is now known that some physical and chemical HIPS characteristics are closely connected with each other and to clarify the individual effect of one of them on the polymer properties is a complicated problem. Thus, the present paper deals with an attempt to establish, by means of statistical methods, the quantitative correlation between HIPS elongation at break and impact strength and MW and MWD of the polystyrene matrix, copolymer and gel quantity, and morphological characteristics (12 parameters in all).