Monte Carlo simulations of structure and entanglements in polymer melts

Atomistic models of short chain branched (SCB) polyethylene melts have been equilibrated at 450 K using a connectivity altering Monte Carlo method. Quantities related to the chain dimensions and entanglements have been determined. The simulated tube diameters, 〈app〉, of SCB melts are found to scale with the backbone weight fraction, ϕ, as 〈app〉∼ϕ− 0.46, close to the scaling predicted by the binary contact model, 〈app〉∼ϕ− 0.5. Similar relationships are observed experimentally for polymer solutions, and reproduced by the present methods.