Structure, and Mechanical and Thermal Properties of Vinyl-Polydimethylsiloxane/Zinc Dimethylates/Isobutylene-Isoprene Rubber Composites

The vinyl-polydimethylsiloxane (v-PDMS) composite reinforced by micron size ZDMA particles previously showed high modulus, thermal stability, solvent-proofness, and good processing ability. However, its poor damping properties limited usages. Thus, incorporation of new polymers into the composite was imperative to improve its loss factors. With a similar solubility parameter and good damping properties, isobutylene-isoprene rubber (IIR) was melt-blended in, then heat-pressed and cross-linked. The v-PDMS/ZDMA/IIR composites gotten were characterized by scanning electric microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), mechanical tests, dynamic mechanical analysis (DMA) and thermal gravimetric analysis (TGA) methods. The IR spectra of the composites illustrated that the incorporation of IIR was successful. The SEM observation showed good dispersion of the IIR, and the increasing deformation on the surface with growing dosage of IIR. The incorporation of IIR rubber decreased the composite's modulus sharply and also the tensile strength, but improved the elongation and damping properties of the v-PDMS/ZDMA composites at low temperature. The TGA test results in N2 gas showed the composites had good thermal stability below 350 & DEG;C, then deteriorated at higher temperature owing to the decomposition of the IIR at 400 & DEG;C. The decomposition activation energy at 400 & DEG;C was determined by the Kissinger method.