Production and characterization of UHMWPE/fumed silica nanocomposites

Ultrahigh-molecular-weight polyethylene (UHMWPE)/fumed silica nanocomposites were prepared via in situ polymerization using a bi-supported Ziegler-Natta catalytic system. Nanocomposites with different nanoparticle weight fractions were produced in order to investigate the effect of fumed silica on thermal and mechanical properties of UHMWPE/fumed silica nanocomposites. The viscosity average molecular weight (M) of all samples including pure UHMWPE as the reference sample and nanocomposites were measured. Scanning electron microscope (SEM) images showed the homogenous dispersion of nanoparticles throughout the UHMWPE matrix while no nanoparticle cluster has been formed. Crystallization behavior of nanocomposites was investigated by differential scanning calorimetry (DSC), which showed a slight increase in melting temperature by enhancing the nanoparticle concentration while no significant change was observed in the crystallization temperature as the fumed silica concentration enhanced. The improvement in all thermal stability parameters was recorded by thermogravimetric analysis (TGA). Besides, via tensile testing, it was confirmed that addition of nanoparticles caused considerable improvement in such mechanical properties as Young's modulus, yield stress, and tensile strength of samples while the elongation at break declined by addition of more nanoparticles. POLYM. COMPOS., 2012. (c) 2012 Society of Plastics Engineers