Raman microimaging of polymer blends

Raman microimaging was used to estimate the effect of the silica filler on phase separation in binary polymer blends composed of brominated poly(isobutylene-co-para-methylstyrene) (BIMS) and cis-1-4-polybutadiene (BR). The domain sizes, relative concentration of polymer components within domains, and distribution of particulate silica filler and zinc stearate curative were characterized for blends of different compositions and history of aging treatments. The presence of increased concentrations of precipitated silica results in better polymer morphology since domain sizes are reduced. Increased temperature treatment also decreases domain sizes up to about 150 degreesC, but treatment at 200 degreesC appears to induce separation of the elastomer components. Silica is usually found near the centers of the BIMS domains. There is little difference in silica distribution before and after curing.