Effect of natural and organically modified montmorillonite clays on the properties of polydimethylsiloxane rubber

Abstract

The effects of natural (MT) and organically modified (O-MT) montmorillonite clays on the properties of polydimethylsiloxane (PDMS) rubber were evaluated. Rubber composites with different clay contents were prepared by a compounding procedure in an open two-roll mill, which was followed by a compression-molding step in which the PDMS matrix was peroxide crosslinked. The clay rubber composites were characterized by swelling measurements in toluene, thermogravimetric analyses, X-ray diffraction, scanning electron microscopy, and tensile tests. The introduction of MT restricted the solvent swelling and increased the crosslinking density of the rubber, which indicated the formation of a covalent filler-matrix interface. The enhanced interaction between MT and PDMS reduced the aggregation size of MT particles in the MT composites and promoted an increase in the separation of the clay layers. When the rubber was filled with O-MT, a higher solvent amount was incorporated in the material, and this trend increased with the clay content. Moreover, the low interaction between O-MT and the PDMS chains resulted in larger clay aggregates in the O-MT composites compared to those with MT. Despite the different interface natures, both clays enhanced thermal stability and acted as reinforcing fillers in relation to Young's modulus and tensile strength.

Effects of Fumed and Mesoporous Silica Nanoparticles on the Properties of Sylgard 184 Polydimethylsiloxane

“…The ratio remarkably decreased with the silica concentration, and the ratio was even down to 0.486 when the concentration of MCM-41 was 20 wt %, which is almost 60% lower than that of pure PDMS. The silica nanoparticles increased the crosslinking density of PDMS [26]. According to the Flory-Rehner rubber swelling theory [30], the increase of crosslinking density decreased the swelling ratio of PDMS.…”

“…Hence the CTE of PDMS can be decreased by adding silica nanoparticles. On the other hand, covalent bonds between silica nanoparticles and PDMS and hydrogen bonds between silica nanoparticles formed [16,26]. The bonds caused large interaction between PDMS and silica nanoparticles, and the interaction restricted the heat deformation of PDMS.…”

Influence of Boron Nitride on the Network Structure and Properties of Poly(dimethylsiloxane) Composite Materials

“…The average molar mass between cross linking points (M C ) was calculated using the Flory-Rehiner equation for a tetrafunctional polymeric network Equation 3 [18]. The polymer volume fraction (φ pol ) was calculated by Equation 4 [17]. χ was determined as a function of concentration according to [19] Equation 5.…”

“…Following the equilibrium solvent uptake, the samples were removed from toluene and allowed to dry in air for a minimum of 24 hours and re-weighed. The swelling ratio (S R ) of the polymer network was calculated by using Equation 1 [17] and the sol fraction was determined using Equation 2. The average molar mass between cross linking points (M C ) was calculated using the Flory-Rehiner equation for a tetrafunctional polymeric network Equation 3 [18].…”

Synthesis and properties of silicone/montmorillonite nanocomposites by in-situ intercalative polymerization

“…Polymer/clay nanocomposites can solve these problems. Several studies have reported about silicone rubber/MMT nanocomposites (Dong et al, 2006;Kaneko & Yoshida, 2008;Kim, Kim, Shim, & Yoon, 2008). However, there are few studies about silicone/clay nanocomposite.…”