STRESS RELAXATION AND CURING OF FLUORINATED ELASTOMERS.

Stress relaxation of elastomeric materials is one of the principal causes of mechanical failure of elastomeric components in today's flight vehicle. This phenomenon of stress relaxation in current fluorosilicone elastomers was thoroughly investigated and the results reported. The most significant conclusion from this work is that after the measurement of an elastomeric compound of different crosslink densities that random chain scission of polymer chains is responsible for stress decay during relaxation. A rate of modulus decrease in intermittent measurements is only slightly lower than the continuous relaxation rate, it is concluded that only a small fraction of the broken bonds are reformed. The information presented provides some insight as to the points of weakness in an elastomers vulcanizate and at the same time indicates an area where research efforts should be directed if we are to find elastomers having high strength at elevated temperature. (Author)