Mesoscale modeling of random chain scission in polymer melts*

The traditional approach to recycling polymers involves thermal degradation of the material to recover the monomer. However, such a process creates unwanted side products. Controlled degradation to oligomers could potentially overcome challenges in recycling to usable products with sufficiently high yield. Herein we develop a mesoscale framework to model random scission in polyethylene melts at high temperatures. Dissipative particle dynamics (DPD) approach is used along with mSRP (modified segmental repulsive potential) formulation, which allows one to capture the effects of entanglements in polymer melts. We account for the temperature dependence of the probability of bond breaking. We systematically characterize weight fraction, number fraction, degree of polymerization, and dispersity of polymer fragments during random scission at a range of high temperatures. We identify the conditions at which the weight fraction and number fraction distribution of polymer fragments approximately follows the Flory-Schulz distribution. Modeling thermal degradation of polymers on mesoscale can potentially assist in developing alternative strategies for polymer recycling and upcycling.