Microstructural Evolution in Linear Low Density Polyethylene During Peroxide Modification: A Monte Carlo Simulation Study

Abstract

A Monte Carlo (MC) simulation is performed on peroxide induced branching reactions in a linear low density polyethylene (LLDPE) melt processed with different dicumyl peroxide (DCP) concentrations at various processing times and temperatures. The MC simulation can successfully monitor the microstructural changes due to the induced long chain branching (LCB), decreased terminal double bonds, and increased trans vinyl bonds in LLDPE during peroxide modification. The induced structural changes are in good agreement with the experimental results obtained by rheometery and SEC analysis. The changes in the gel content, Mtrue‾normalw, and MWD as a result of the peroxide modification are also determined. The simulation results also reveal that the chemical mechanism by which the modification proceeded is closely related to the changes in concentrations of reactive vinyl species of the PE molecules. Moreover, the results indicate that the degree of induced LCB increases almost linearly with the DCP concentrations. The findings of this paper indicate that the MC simulation method is able to predict the suitable processing conditions needed for inducing desirable structural changes in a LLDPE.

Toward In Situ Compatibilization of Polyolefin Ternary Blends through Morphological Manipulations

“…It is to be noted that the unusual upturn may also be due to formation of radicals and reactions between the two polyolefins however, our recent investigations on melt mixing of polyethylenes (PEs) with peroxides in order to produce branched and crosslinked PEs, showed that the measured gel contents were very negligible even in presence of peroxides at low contents and no degradation occurred up to 300 °C. Based on these results, we can conclude that under the processing conditions used for the current work, i.e., 250 °C the formation of radicals and reactions between the HDPE and PP is not likely to happen.…”

Branching degree and rheological response correlation in peroxide-modified linear low-density polyethylene

“…In our previous work, by using the MC simulation, the variations of pendent, terminal, and trans vinyl groups during peroxide modification were reported. It was reported that the concentration of terminal double bonds decreased in the course of modification whereas that of trans double bonds increased.…”

“…In continuation, Monte Carlo (MC) simulation were performed on peroxide‐induced branching reactions in an LLDPE melt processed with different dicumyl peroxide (DCP) concentrations at various processing times and temperatures. The MC simulation could successfully monitor the microstructural changes due to the induced LCB, decreased terminal double bonds, and increased trans vinyl bonds in LLDPE during peroxide modification.…”

When Polymer Reaction Engineers Play Dice: Applications of Monte Carlo Models in PRE

“…Golriz et al used a MC model to study how dicumyl peroxide (DCP) changed the microstructure of linear low‐density polyethylene (LLDPE) using different DCP concentrations, processing times, and temperatures. In their proposed mechanism, the dominant steps were DCP decomposition, hydrogen abstraction, and chain termination by combination.…”