RELAXATION OF RANDOMLY CROSS-LINKED POLYMER MELTS

The dynamical properties of randomly cross-linked polymer melts, far above the vulcanization threshold, are studied using molecular-dynamics simulations. The mean-square displacements of the middle and end monomers of the chains as well as the cross-links are considered. The dynamic scattering function S(q,t) as measured by neutron spin echoes is also calculated. The average strand length between two cross-links is about 1/4 of the entanglement length of the un-cross-linked melt. By introducing a new intermonomer potential, we can explicitly test the influence of trapped entanglements. For the present system, the frozen entanglements change the plateau modulus by about 25%.