Monte Carlo simulations of the spatial structure of end-linked bimodal polymer networks: part II

The article presents the results of Monte Carlo simulations of bimodal netw orks performed with the Bond-Fluctuation-Algorithm. First the sol-fractions of networks with different ratios of short chains were studied and found t o be always less than 2%. Concerning clustering behaviour, we saw that whil e random networks always form a main cluster containing more than 95% of al l chains, simulated networks with less than 80% short chains do not form a main cluster. The density profiles during the swelling process show that cl ustering is reflected in a lower swelling degree and a sharper transition z one between the inner part and the boundary regions of the network. Finally , comparing the density distributions of crosslinkers of unimodal and bimod al networks, we found that all unimodal networks have a more ordered struct ure in their interior than in the melt. On the other hand, bimodal networks , where the ratio between long and short chains leads to equal masses of th e fractions, show a superposition of two separate density distribution peak s, leading to a broader distribution than the Gaussian distribution found f or a melt. (C) 2001 Elsevier Science Ltd. All rights reserved.