Correlation of Morphology, Mechanical Properties and Processing Conditions of Modified High Impact Polystyrene
Due to its great toughness high impact polystyrene (HIPS) is widely applied as a construction material. It is known to be a composite material in which the rubber phase is dispersed in a polystyrene matrix (1). Varying synthesis conditions can change the polymer morphology to some extent, the rubber particles size and volume fraction in particular; this significantly affects HIPS properties (2). It seems possible to improve a number of mechanical properties by introducing a definite quantity of modifying additives of a different nature into the polymer. Triblock styrene and diene copolymers possessing a number of valuable properties (3) can be used as these modifying additions. Thus, this paper deals with the effect of elastomer addition, introduced into the extrusion process on HIPS morphology and some strength properties. To introduce the elastomer, a single screw extruder was used. The morphology of modified HIPS was studied by electron microscopy, impact strength (according to Charpy, without a notch), elongation at break, and tensile strength. The blending conditions of copolymers A and B with HIPS and their effect on mechanical properties are presented in Table I. It is seen that the introduced copolymer greatly affects the impact strength and elongation at break (depending on extrusion conditions).
KeywordsShear Rate Impact Strength Extrusion Process Rubber Phase Extrusion Condition
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