Effect of Thermal History on β-Nucleated Polypropylene Homopolymer

Abstract

β-nucleant is used in polypropylene homopolymer (h-PP) primarily to improve its toughness as this particular property is important for piping and pipe coating application. In this work, the effect of β-nucleating agent on h-PP as topcoat material for pipe coating was investigated. The distribution of the nucleating agent in h-PP was controlled by solid-phase reactive extrusion. It was found that when subjected to second cycle of thermal exposure, the effect of β-nucleant upon h-PP crystallinity had increased significantly. This was desirable as it would enhance topcoat toughness. Several heating cycles were used to mimic the number of thermal exposures during processing. The effect of this simulated thermal history on the toughness enhancement was assessed and reported. The work has shown that, after a number of consistent thermal cycles, the percentage of β-crystals phase remained level. This will provide a much needed assurance on thermal and mechanical consistency in β-nucleated h-PP as well as enhance its viability for pipe coating applications.