Filler phase distribution in BIMS Blends

摘要

Carbon black (CB) filler phase distributions in filled BIMS/BR [brominated poly (isobutylene-co-para-methylstyrene)/poly(1,4 cis-butadiene)] blends were quantified by image processing the blend morphologies obtained from tapping-phase atomic force microscopy (AFM). The CB filler is found to preferentially partition into the BIMS phase; this preference is enhanced with an increase in BIMS content. Morphologies of BIMS/BR blends with 40 to 60 wt% BIMS were found to be co-continuous. Three-dimensional finite element modeling based on randomly generated co-continuous blend morphologies and experimentally determined filler phase distributions were found to accurately predict blend tensile properties. Preferential filler partition into the BIMS phase may account for the observed synergistic improvement in abrasion resistance of these blends. The preferential filler partitioning into the polar BIMS polymer phase is a combination of the results of temperature-insensitive physical interactions between the benzylic bromine in BIMS and the filler functional groups. Carbon black and silica filler phase distributions in BIMS blends with various high diene hydrocarbon rubbers were further quantified. Preferential filler partitioning into the BIMS phase was found for either carbon black or silica use. Using a four-pass Banbury phase mixing sequence, most of the fillers are incorporated into the BIMS domains in the six binary blends studied: cis-BR, four sSBR polymers having varying microstructures, and NR. Significantly less filler partitions into the BIMS phase during Brabender mixing of pre-compounded carbon black with BR followed by BIMS addition. Due to the higher temperatures employed in Brabender mixing, viscosity mismatch between the BIMS and filled BR leads to larger polymer domain sizes and lower interfacial areas for filler partitioning. The use of mixing techniques and lower amounts of BIMS in blends with diene rubbers affords control of the filler phase distributions.