Polypropylene-(high density polyethylene) precipitation from stirred solutions

Abstract

The fast precipitation of mixtures of polypropylene (PP) with high density polyethylene (HDPE) from decalin solutions is affected by the stirring rate of the solutions. With fast stirring, two types of precipitates were obtained viz. globules dispersed in the liquid phase and fibres adhering to the stirrer. Studies by i.r., WAXD, DSC and optical microscopy indicated that the fibrous precipitate is more birefringent, richer in HDPE and richer in the PP fractions with higher isotactic helical content than the globular precipitate. The dried precipitates recrystallize during storage. HDPE undergoes “pseudo-monoclinic”-orthorhombic solid state phase transition.