Paper Number
PM15 

Session
Polymer Melts: From Molecular Rheology to Processing

Title
Effects of branching on rheology of polyethylene combs: A molecular dynamics simulation study

Presentation Date and Time
October 17, 2018 (Wednesday) 10:15

Track / Room
Track 2 / Plaza I

Authors (Click on name to view author profile)

  1. Perahia, Dvora (Clemson University, Department of Chemistry)
  2. Wijesinghe, Sidath (Clemson University, Department of Chemistry)
  3. Grest, Gary S. (Sandia National Laboratories)

Author and Affiliation Lines (in printed abstract book)
Dvora Perahia1, Sidath Wijesinghe1, and Gary S. Grest2
1Department of Chemistry, Clemson University, Clemson, SC 29634; 2Sandia National Laboratories, Albuquerque, NM 87185

Speaker / Presenter 
Perahia, Dvora

Text of Abstract
Linear, branched, and star polymers exhibit distinctive rheological behavior, critical to their processing, depending on their topology. Early studies have shown that the effects of branches differ below and above the entanglement length and branches on the length scale of the entanglement length of the backbone results in increased viscosity. Using coarse grained molecular dynamics simulations we study the effects of degree of branching, including their length and density on the rheology of entangled polyethylene melts, with branch lengths above and below the entanglement length while the branching density is varied. Our coarse grained model are able to capture the flow properties observed by experimental studies and provide fundamental new correlations between branching length-densities and rheology for entangled branched polymers. As expected branched polyethylene chains diffuse slower than their linear analogs. For polymer melts with same MW, diffusion is predominantly governed by the branch length and only slightly affected by the branching density. Beyond the new model for coarse grained of branched polymers, this study has provided new insight into a long standing challenges in polymer rheology.