AbstractThe physical and elastomeric properties of several DEXSIL 300 (10‐SiB‐3) samples were investigated. Modulus—temperature studies were used to determine the glass transition temperatureTg, the melting temperatureTm, and the oxidative crosslinking temperatureTox. Stress relaxation in air at elevated temperatures was used to compare the oxidative stability of the various formulations. It was found that theTgof DEXSIL 300 is some 30°C lower than that of DEXSIL 200 (10‐SiB‐2) polymers, extending the elastomeric properties of DEXSIL 300 to lower temperatures. At high temperatures, both silica filler and ferric oxide are found to increaseToxto an ultimate value of 320°C. The effects of cure were also investigated, and γ‐radiation‐cured samples exhibit a slight degree of crystallinity with a melting temperatureTm= +40°C. No crystallinity was detected in similar peroxide‐cured samples. Stress relaxation results are presented in support of the modulus—temperature studies. Formulations with a lowToxshow oxidative effects earlier than those with a higher oxidation temperature. Silica‐and ferric oxide‐filled samples exhibit improved oxidative stability, as do samples fille
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