Crystallization behavior of ultrahigh-molecular-weight polyethylene/ polyhedral oligomeric silsesquioxane nanocomposites prepared by ethylene in situ polymerization

A [3-t-Bu-2-O-C6H3CH=N(C6F 5)]2TiCl2 catalyst (bis(phenoxyimine)titanium dichloride complex - FI catalyst) was immobilized on disilanolisobutyl polyhedral oligomeric silsesquioxane (OH-POSS) to prepare ultrahigh molecular-weight polyethylene (UHMWPE)/polyhedral oligomeric silsesquioxane (POSS) nanocomposites during ethylene in situ polymerization. The dispersion state of POSS in the UHMWPE matrix was characterized by X-ray diffraction measurements and transmission electron microscopy. It was shown that the OH-POSS achieved uniformed dispersion in the UHMWPE matrix, although its polarity was unmatched. The isothermal and nonisothermal crystallization behavior of the nanocomposites was investigated by means of differential scanning calorimetry. The crystallization rate of the nanocomposites was enhanced because of the incorporation of POSS during the isothermal crystallization. POSS acted as a nucleus for the initial nucleation and the subsequent growth of the crystallites. For nonisothermal studies, POSS showed an increase in the crystallinity. The crystallization rate of the nanocomposites decreased because the presence of POSS hindered the crystal growth. © 2014 Wiley Periodicals, Inc.