Modification of Polypropylene by Blending with Oligopinene

Abstract

The changes in physical properties, melting behaviour and morphology of polypropylene (PP) in binary blends with low molar mass oligopinene resin were evaluated. Melting mixtures were prepared in a Haake Rheocord at 473 K, 30 rpm, for 600s; an abrupt drop in torque was observed when the blends were enriched by oligomer. At room temperature, with up to 20% of oligopinene, the nominal stress-strain curves of the blends showed a change in behaviour from ductile to brittle. The elastic modulus increased, and the other mechanical parameters were also dependent on the composition. The density increased linearly with oligopinene content, and the hardness also increased with the amount of oligomer present. No phase segregation was observed, before or after etching with heptane. The SEM results indicated that the oligopinene component is located mainly in the intraspherulitic regions of the PP.