Structure development and crystallization behaviour of PP/nanoparticulate composite

The structure development and crystallization behaviour of polypropylene (P P) containing nanoparticles of calcium phosphate prepared by a new route ba sed on matrix mediated control of growth and morphology was investigated by X-ray diffraction (XRD), optical microscopy and DSC techniques. The result s obtained were compared with that of PP containing conventionally prepared calcium phosphate (CaP0). Both nanoparticle filled PP as well as CaP0 fill ed PP crystallized in monoclinic cr crystalline phase. However, considerabl e changes were observed in the relative intensities of the XRD peaks, espec ially the peak II (040 reflection), in the case of PP filled with nanosize calcium phosphate. The isothermal crystallization curves showed dramatic in crease of crystallization rate and decrease in till value for PP/nanopartic ulate composites resulting in a rapid decrease in the ultimate spherulite s ize as compared to PP/CaP0 samples. The nucleating efficiency was found to be dependent on the particle size as inverse exponential power law. These r esults were further confirmed by DSC analysis. The optical transparency of the PP/nanoparticle composites was found to be much higher than that contai ning conventional CaP0 for the same concentrations and this could be associ ated with the reduction in the PP crystallite size. (C) 2001 Elsevier Scien ce Ltd. All rights reserved.