Distribution of Elastomers and Silica in Polymer Blends Characterized by Raman Microimaging Technique

Abstract

Abstract Raman microimaging technique was used to study the distribution of silica filler and elastomer domains in binary and ternary polymer blends containing cis1–4-polybutadiene BR; brominated poly(isobutylenecoparamethylstyrene) BIMS; Natural Rubber, NR; and/or Styrene-Butadiene Rubber, SBR. Contour maps depicting distribution of the elastomer phases and silica within each phase were obtained for 1 μm thick sections of blends having different compositions. All polymers were uniformly distributed throughout the blends. However, on a micrometer scale local fluctuations were clearly observed using Raman microimaging. The BR component is not as compatible with BIMS as are the other polymers based upon the presence of some single-phase BR domains exceeding 5 μm. Addition of the third polymer, either SBR or NR, to the blend improves the BR compatibility with BIMS since the BR domains are not as large. At low concentrations in a ternary blend, the NR phase appears concentrated near the BR domains, but in samples with higher NR concentrations, the natural rubber forms it own network and may also be found near the BIMS domains. The SBR phase was found to be near or within the BR domains. Silica was dispersed throughout the polymers in each blend, but tended to aggregate near the boundaries of the BIMS domains. Sometimes the silica was present within the BIMS domains, but did not locate within a BR domain.