Prediction of branch on branch and topological characteristics of low‐density polyethylene polymerization by a novel stochastic approach

Abstract

A novel approach using Monte Carlo method applied to simulation of low-density polyethylene (LDPE) polymerization in tubular reactor showing topological characteristics, and the comprehensive kinetic mechanism has been taken into consideration.The results show the precise details of the structure of a chain in the three levels of the backbone, the main branches, and branches on branch. The chain types include dead polymer, dead polymer with unsaturated end, and live polymer with primary radical, secondary radical, and tertiary radical. In this work, the branches on branch were identified in terms of number, length, and position of the branch. Sixty percent of branches on branch are 1 to 5 carbons long, and the longest branch on branch is about 50 carbons. Thus, this study provides a tool for more accurately mapping the polymer chains architecture, superior to determine the number, and position of longand short-chain branches in past researches. Finally, this approach will advance the prediction of microstructure-related properties of polymer one step further. K E Y W O R D S branch on branch, LDPE, Monte Carlo simulation, radical polymerization, topological characteristics

A graph theory assisted Monte Carlo algorithm for simulating the topology structure of LDPE and connection with molecular dynamics simulation

“…In order to validate the accuracy of our MC model and compare the difference in typology record method proposed here with previous work, [27][28][29] the algorithms are applied to a real industry LPDE process.…”

“…For the current commonly employed typology symbolization method, 27–29 the backbone carbon chain is defined as the path from the initial monomer to the active site monomer in the LDPE chain. However, in our typology storage strategy, the backbone and branch are not explicitly pointed out.…”

“…As it was, the calculated LBCD would be deviated from the experiments. Despite the above deviation, Meimaroglou's work was the first to give a comprehensive and easy‐to‐implemented chain symbolization method in this research area, and it was still used as the fundamental of some recent publications 28,29 . Neuhaus et al 22 developed another structure symbolization method in their LDPE typology MC simulation algorithm.…”

Modeling Low‐Density Polyethylene (LDPE) Production in Tubular Reactors: Connecting Polymerization Conditions with Polymer Microstructure and Rheological Behavior

“…Moreover, a modification to Equation (26) was proposed in this work, in which parameter Aʹ is a linear function of the calculated…”

“…The molecular predictions usually include bivariate molecular weight–long chain branching distributions (MWD–LCBD), molecular weight–short chain branching distributions (MWD–SCBD), the number of short and long branches per 10 3 carbon atoms (SCB/1000C and LCB/1000C), the branching density distribution, the bivariate branching order‐molecular weight distribution, seniority/priority distributions, the mean‐square radius of gyration ($$\overline {S_0^2} $$), and the branching index ( g ). [ 4,8,24–27 ] MC approaches are usually expensive both in storage requirements and computation time.…”