CRYSTAL STRUCTURE OF POLYPROPYLENE FILLED WITH RARE-EARTH-OXIDES

The effect of a fine powder of Y2O3, Nd2O3, and Ho2O3 on the crystal s tructure of isotactic polypropylene (iPP) was studied with WAXD and DS C techniques. The results showed that the addition of the three rare e arth oxides (REOs) can increase the crystallite size of the alpha-form crystal and the degree of crystallinity of iPP at an annealing temper ature of 120 degrees C and that both Y2O3 and Nd2O3 are the beta-nucle ator of iPP. REOs enhance the overall growth rate of the spherulites o f iPP. All the iPP samples filled with REOs which were crystallized is othermally at 132 degrees C from the melt exhibited their melting peak s of the beta-form on the DSC heating traces, indicating that the REOs are the nucleating agents for both the alpha- and beta-forms of iPP u nder isothermal conditions. (C) 1996 John Wiley & Sons, Inc.