STUDY ON THE RELATIONSHIP BETWEEN THE MECHANICAL-PROPERTIES AND PROCESSING FOR SELF-REINFORCED POLYMERS .2. A QUANTITATIVE CHARACTERIZATIONOF TENSILE MODULUS FOR SELF-REINFORCED POLYMERS

In this paper the model structure of super-drawn polymers and the appr oaches to characterize the tensile modulus of highly oriented UHMWPE ( ultra-high molecular weight polyethylene) have been reviewed. It is fo und that the models and expressions for tensile modulus cannot predict the correlation between the tensile modulus and the super-draw ratios of processing of highly oriented UHMWPE. A new approach to characteri ze the mechanical properties of highly oriented UHMWPE is proposed. A new correlation between the ultra-high tensile modulus of highly orien ted UHMWPE with the processing conditions and primary structure of UHM WPE was derived from a theory of stress-induced crystallization for po lymer entangled networks. When drawing with constant rate and structur e with the primary molecular weight distribution having the Schulz-Flo ry distribution function introduced into the above correlation, the de pendences of super-draw ratios and the primary molecular weight of pol ymers upon the tensile modulus were obtained. A large number of experi mental data for UHMWPE and thermotropic liquid crystalline polymers we re used to verify the relation between tensile modulus and super-draw ratios. A series of lines was obtained by plotting In (E) versus (alph a - 1)alpha'3h and 1/E versus (L/L0)alpha'L/L0 and (L0/D0)alpha'(LID)a lpha'L/D An expected limiting modulus (E(c) = E) was achieved from the relation by extrapolating the super-draw ratios to infinity.