THE ROLE OF TEMPERATURE IN THE ENTANGLEMENT KINETICS OF A POLYMER MELT

Large-amplitude oscillatory shear (LAGS) experiments were conducted at different temperatures on a molten low-density polyethylene standard, designated IUPAC LDPE X. Jeyaseelan et al. (1993) have successfully e mployed a simplification of transient network theory to describe the L AGS behavior of this polymer melt, at 150 degrees C. The transient net work is described by two kinetic rate constants, one for the formation of entanglements due to Brownian motion (k(1)), and another for the d estruction of entanglements (k(2)) due to the imposed deformation. Upo n comparison of the predictions of this transient network theory with the measured LAGS behavior of this polymer we find that the kinetic ra te constants k(1) and k(2) are invariant in the range of temperatures examined (150 to 190 degrees C). The temperature dependence of departu res departures from linear viscoelasticity is fully accounted for in t he equilibrium entanglement kinetics.