Dynamic Properties of Silica-Filled Polyisoprene Rubbers and Their Blends with Polybutadiene Rubber

Silica-filled rubber vulcanizates are increasingly used in the rubber industry for many different applications. They are used in the manufacture of technical white rubber products, in non-conducting rubber compounds and very importantly in the area of “green tires”. The advantages of low rolling resistance achieved with silica filled compounds as a consequence of reduced tan δ at above ambient temperatures resulting in low hysteresis, can equally well be extended to non-tire products. For example, in the transportation sector the isolation of vibrations produced by a moving vehicle is achieved by the use of rubber-bonded components utilizing rubber compounds with low tan δ. The use of silica-filled technology in these product sectors is gaining recognition in the industry.

 In this study, data is presented to highlight the special attributes of silica filled polyisoprene polymers (NR,DPNR,IR) and their blends with polybutadiene rubber (BR). Data are presented on the use of silane as a coupling agent, as well as the use of pre-reacted silica in these rubber compounds. Dynamic properties of vulcanizates are measured and the trends observed in tan δ, shear modulus and the filler-filler interactions are discussed. Bound rubber measurements and atomic force microscopy (AFM) methods are used to assess rubber-filler interaction and filler macro- and micro-dispersion. Viscoelastic mapping of the compounds using AFM will be related to data from the dynamic tests and the differences observed in the different isoprene rubbers.