Effect of the nucleating agent 1,3 : 2,4-di(3,4-dimethylbenzylidene) sorbitol on the gamma phase content of propylene/ethylene copolymer

摘要

The influence of the concentration of a nucleating agent (NA), namely 1,3:2,4-di(3,4-dimethylbenzylidene) sorbitol (DMDBS), on the gamma phase content in a propylene/ethylene copolymer was investigated by means of Differential Scanning Calorimetry (DSC), Wide-Angle X-ray Diffraction (WAXD), Small- Angle X-ray Scatter (SAXS) and Polarized Optical Microscopy (POM). It was found that the nucleated cPP showed two endothermic peaks, corresponding to the melt behaviors of alpha and gamma crystal; both alpha and gamma crystal forms were present in each lamella within the same spherulite; the gamma phase developed on the edges of a phase lamellae rather than on the less favorable DMDBS nucleating agent; the gamma content in the crystallized samples increased initially with increasing DMDBS concentration and reached a maximum, then decreased with further increment of NA concentration under the non-isothermal condition. We interpreted these results in terms of competition and deposition between alpha and gamma crystals. (C) 2008 Elsevier Ltd. All rights reserved.