THE INFLUENCE OF MOLECULAR WEIGHT ON DEFORMATION-STRENGTH PROPERTIES OF ORIENTED AMORPHOUS POLYMERS,

Tensile tests were carried out on uniaxially oriented films of several amorphous linear polymers, i.e., polymethyl methacrylate, polystyrene, and poly-2, 2-octamethylene-5, 5-dibenzimidazole of different molecular weights. In the range of relatively high molecular weights, the latter were shown to have no direct effect on the mechanical properties of isotropic and oriented polymers. The mechanical properties were determined by the network structure formed during the extension, and by the average degree of orientation of the macromolecular mers. It was concluded that the formation of a particular structure is closely related to the molecular weight of a polymer, and that a given molecular weight can promote or hinder the formation of the corresponding structure under given extension conditions. Author