EFFECTS OF DILUTION DURING CROSSLINKING ON STRAIN-INDUCED CRYSTALLIZATION IN<i>CIS</i>-1,4-POLYISOPRENE NETWORKS. II. COMPARISON OF EXPERIMENTAL RESULTS WITH THEORY

Abstract

ABSTRACT Modern rubber elasticity theory was applied to the strain-induced crystallization results summarized for cis-1,4-polyisoprene in the preceding paper. The calculations adopted the basic assumptions made in the Flory crystallization theory, in some cases retaining the original affine elasticity model and in others adopting the new constrained-junction model. Of the two sets of theoretical stress-strain isotherms thus obtained, those from the constraint theory gave a good account of the experimental results. One major accomplishment was documenting the expected decrease in the constraint parameter κ with increase in dilution during crosslinking. This decrease is due to the fact that the diluting solvent decreases chain interpenetration, which in turn decreases entanglement constraints on the junction fluctuations.