Surface modification of montmorillonite (MMT) using column chromatography technique and its application in silicone rubber nanocomposites

Surface modification of montmorillonite (MMT) was done to improve the basal spacing using a column chromatography technique with quaternary long chain ammonium salt as an intercalent. An increase in d-spacing of organically modified montmorillonite (OMMT) was confirmed by X-ray diffraction and found to increase from 16 to 22 . The d-spacing was maximal (22 ) due to ion exchange column of sufficient length (35 cm) and diameter (5 cm), which provides maximum retention time for proper ion exchange between MMT and ion-exchange resin. OMMT: silicone nanocomposites were prepared by solution blending and then compounded and molded on two roll mill and compression molding machines, respectively. The amount of loading of OMMT was in the range of 2-10 wt%. The rubber chains were uniformly dispersed within and between the exfoliated OMMT plates. The extent of dispersion was measured using atomic force microscopy. The mechanical, thermal, and physical properties were studied. Increased amounts of OMMT loading showed increased silicone:OMMT nanocomposite properties compared to those of pristine silicone rubber due to OMMT exfoliation and uniform dispersion with good wet ability of the rubber chains.