EFFECT OF THE MOLECULAR-MASS DISTRIBUTION ON THE THERMOMECHANICAL PROPERTIES OF LINEAR-POLYMERS

A relationship between the shape of thermomechanical curves and the mo lecular mass distribution of linear polymers is established on the bas is of a model of the physical lattice sites. A formula is derived that relates the temperature of the yield onset (the end of a plateau of t he rubberlike elasticity) to the molecular mass, which proves to be un iversally valid for a wide class of polymers. A method is proposed tha t allows the molecular mass distribution to be estimated proceeding fr om an analysis of the shape of the thermomechanical curve of a polymer in the region of transition from glassy state to viscous flow. A rela tion is obtained that generalizes the Flory formula, describing the ef fect of chain ends on the high elasticity modulus, to the case of low- crosslinked polymers.