Date of Award
8-2025
Document Type
Thesis
Degree Name
Master of Science (MS)
Department
Materials Science and Engineering
Committee Chair/Advisor
Olga Kuksenok
Committee Member
Philip Brown
Committee Member
Igor Luzinov
Abstract
Polyolefins are the primary contributors to greenhouse gas emissions and supply chain energy requirements with respect to other commodity polymers. In order to explore more efficient methods for recycling and upcycling these plastics, it is important to consider the kinetics of polymer fragments during the degradation process to more accurately reflect experimental outcomes. The molecular weight distribution of synthetic polymers is an important factor to consider when synthesizing, processing, and manufacturing industrial plastics. The breadth of this distribution, or dispersity, is determined by the ratio of the weight average molecular weight to the number average molecular weight, and is correlated with material properties. While most theoretical studies consider monodisperse polymer melts, monodispersity is not practically achieved in experiments. There is a pressing need to explore the effect of initial dispersity on the degradation process. We use dissipative particle dynamics (DPD) to probe the effects of initial molecular weight distribution on random scission in linear polymer melts, specifically, linear polyethylene. To capture the effects of entanglements in melts, the modified segmental repulsive potential (mSRP) formulation of DPD is applied. Melts with initial dispersities of 1.05 to 1.20 are considered, which reflects the range of dispersity values of industrial polyethylene with narrow to moderate molecular weight distributions. The Schulz-Zimm analytical expression, which is known to be an accurate predictor of the distribution of polymer chains in polyethylene, is used to simulate and model initially disperse systems. Characterization of results is achieved through the tracking of weight fraction, number fraction, and dispersity of polymer fragments during random scission at high temperatures to quantify the effects of initial dispersity.
Recommended Citation
Simpson, Cassandra L., "Quantifying the Effect of Initial Molecular Weight Distribution on the Degradation of Linear Polyethylene at High Temperatures Using Dissipative Particle Dynamics" (2025). All Theses. 4588.
https://open.clemson.edu/all_theses/4588