Effect of silica-based nanofillers on the properties of a low-density polyethylene/ethylene vinyl acetate copolymer based thermoplastic elastomer

摘要

The effect of pristine silica nanoparticles on a model low-density polyethylene (LDPE)-ethylene vinyl acetate copolymer (EVA) thermoplastic bleand system is explored in this article. Pristine silica nanoparticles were melt-blended with the LDPE-EVA system at 1.5, 3, and 5 wt loadings through the variation of the sequence of addition. In one of the compositions, coupling agent bis3-(triethoxysily)propyl tetrasulfide (Si-69) was used to improve the interaction of hydrophilic silica fillers with the polymer matrix. The blends were compression-molded, and their mechanical, dynamic mechanical, and thermal properties, X-ray diffraction patterns, and morphology were evaluated. The properties of the blends were found to be strong functions of the sequence of addition of nanofillers during their preparation. With Si-60 as a coupling agent, the dynamic storage modulus of nanosilica-based composites was found to increase up to 35. An appreciable improvement in the tension set properties of the thermoplastic elastometer nanocomposites was abserved in all the nanosilica-based films. Morphological studies and dynamic properties clearly indicated that the differential properties of these blend systems primarily stemmed from the extent of dispersion and alternation of crystalline morphology, which in turn was a strong function of preferential incorporation in the LDPE or EVA matrix and the agglomeration tendency of the nanofillers. (c) 2008 Wiley Periodicals, Inc.