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In this article, the effects of the b-nucleators WBG and WOT on the crystallization behavior and morphology of isotactic polypropylene (iPP) were investigated using a combination of differential scanning calorimetry (DSC), wide-angle X-ray (WAXD), polarized optical microscopy (POM) and atomic force microscopy (AFM). The results showed that the amount of b-form and the spherulite size decreased with increasing WBG contents. At about 0.15 wt. % WBG nucleator, the formation of the b-form was evidently observed. Whereas, for the iPP with low content of WOT nucleator, the formation of the b-form was almost the same as that of pure iPP.

A new method was developed for the microcellular processing of polycarbonate (PC) thin sheets by compression molding above PC's glass-transition temperature and below its melting temperature within a few minutes. The effects of the foaming time, foaming pressure, foaming temperature, and foaming agent active ratio on the cell size, cell density, and relative density were studied. The structures of the microcellular PC foam were controlled in the foaming process by carefully choosing the foaming parameters. In addition, the thermal, dynamic mechanical thermal, and electrical properties of the microcellular PC foam were investigated. A differential scanning calorimetry analysis showed that the microcellularly processed PC may have a plastication effect. The variation of the storage modulus, loss modulus, and tan ␦ under dynamic mechanical thermal analysis was in accord with the calorimetry analysis. The measurement of the electrical property demonstrated that the insulation ability of the microcellular PC thin sheet was obviously enhanced and the dielectric strength of the microcellular PC foam was decreased compared to the unfoamed PC.

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