Polyester and polyether urethane elastomers have been prepared as composites with fumed silica. The polyurethane elastomers were thermoplastic and consist of rubbery domains of the polyester or polyether with dispersed hard urethane domains. The fillers provide increased stiffness of the rubbery domains and reinforce the hard domains, which act as physical crosslinks. The composites were characterised using thermogravimetry and differential scanning calorimetry. Dynamic mechanical analysis was used to measure the properties with change in frequency and temperature. Activation energy for the elastomer phase glass transition was obtained from the multiple frequency results and related to the interaction of polymer with filler. Creep recovery measurements showed that the filled polyurethanes provided improved elastomeric response.
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