Temperature dependence of the mechanical properties of network polymers based on oligo-oxyethylene-urethane methacrylates

Abstract

The glass transition temperature T g was determined on the basis of the thermomechanical curves for amorphous network polymers based on oligo(oxyethylene-urethane methacrylates) of different molecular weight. It was found that T g is proportional to the reciprocal of the molecular weight of the original oligomer and ceases to be a function of block length if the oligomer has a molecular weight of >2000. The limiting values obtained for the stress and the elastic modulus of the network crystalline polymers rise as the length of the oligomeric block increases, and in the case of n⩾60 these values become practically constant, which is due to the formation of physical crosslinks increasing the overall network density. For the same polymers in the high elastic state the limiting stress values fall as the block length increases, and at n⩾60 become virtually independent of n.