RTV Silicone Rubber Filled with Surface Modified Montmorillonite

The surface modification of pristine montmorillonite (MMT) with four kinds of coupling agents for reinforcement of the room temperature vulcanized vinyl-terminated polydimethylsiloxane (RTV PDMS) networks was investigated. The four coupling agents containing gamma-glycidoxypropyltrimethoxysilane (KH-560), gamma-methacryloxypropyltri methoxysilane (KH-570), isopropyl trioleic titanate (NDZ-105), and stearic acid (SA) without N, P, or S compounds were used because the coupling agents harmless to the platinum catalyst used normally in the curing of RTV vinyl-terminated PDMS. The interaction between MMT particles and coupling agents was confirmed by diffused reflectance infrared spectroscopy (DR-FTIR) tests. By scanning electron microscopy (SEM) characterization, surface modified MMT was dispersed heterogeneously in the PDMS matrix for all four coupling agents. By X-ray diffraction (XRD) characterization, the interlayer distances of the four surface modified MMT were not changed. Dielectric tests showed that the dielectric constant and dielectric loss of PDMS filled with KH-560, KH-570, and SA treated MMT were decreased comparing with those of PDMS filled with pristine MMT. With the increasing content of MMT treated with KH-570, the dielectric constant and dielectric loss value of PDMS composites increased.