Nano-perlite as an alternative reinforcing filler to silica in PDMS composites

Official URL: http://risc01.sabanciuniv.edu/record=b1534433 (Table of Contents)

Perlite is a highly potential national resource, and its use in silicone elastomer compounds as an alternative reinforcing filler to commercial grade fumed silica is targeted in this thesis work. Thus, comparative results are projected to be acquired. Expanded and raw perlite are characterized using X-Ray Diffraction (XRD), BET Surface Area Analyzer, Pycnometer and Scanning Electron Microscopy (SEM). Attrition mill is used to reduce particle size of expanded perlite. Dynamic Light Scattering (DLS) results showed that particle size was around 260 nm, whereas Scanning Electron Microscopy revealed particle size was between 40-50 nm. Using BET surface analysis and surface titration experiments, hydroxyl group density on expanded perlite surface was calculated, which came out to be 0.0406 –OH/nm2. Perlite and PDMS masterbatches were prepared using a high-speed mixer and mechanical and rheological properties of the elastomers cured from the masterbatches were studied using a Universal Testing Machine (UTM) and Rubber Process Analyzer (RPA 2000). Surface of the mineral was further modified using Hexamethyldisilazane, increasing wettability and mechanical properties of the elastomer samples. Rheological studies and SEM characterization showed a homogeneous distribution of the filler. As a result, surface modified nano expanded perlite exhibited uniform dispersity in the PDMS matrix, similar to commercial grade fumed silica, and their composites exhibited good mechanical properties.