Monte Carlo simulations of structure and entanglements in polymer melts

Abstract

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, 〈a_pp〉, of SCB melts are found to scale with the backbone weight fraction, ϕ, as 〈a_pp〉∼ϕ^− 0.46, close to the scaling predicted by the binary contact model, 〈a_pp〉∼ϕ^− 0.5. Similar relationships are observed experimentally for polymer solutions, and reproduced by the present methods.

Keywords::

• polyolefins
• Monte Carlo
• primitive path analysis
• entanglements

Acknowledgements

We thank Prof. M. Kröger for providing the Z1 code, Dr C. Tzoumanekas for providing the CReTA code, Prof. SK Sukumaran for discussions, and Director Dr T. Kakigano for encouragement and support. Mitsui Chemicals, Inc. is thanked for the permission to publish this work. J.R. acknowledges financial support through the Ramon y Cajal programme, contract RYC-2011-09585.