Date of Award


Document Type

Thesis (Master's)

Department or Program


First Advisor

wenlin zhang


Abstract Polyethylene (PE) and isotactic polypropylene (iPP) are arguably the most widely used and economically beneficial recycling plastics in the world. We investigate the crystallization of PE and the interaction between PE and iPP on a microscopic scale using molecular dynamics (MD) simulations. However, notable discrepancies in the melting temperatures of PE are reported using the currently popular all-atom optimized potentials for liquid simulations (OPLS-AA) force field. We employed an optimized parameter set for long hydrocarbon (OPLS-L) to study the physical properties of PE and use the original OPLS-AA for iPP. In our simulations, we show improved gauche-trans ratios of PE and accurate PE melting temperature with different chain lengths. The Flory-Huggins χ parameter between PE and iPP is overestimated by simulations comparing with existing experimental data by building a PE/iPP phase separation system, and the interfacial widths are around 5 nm under different temperatures. We expect our findings to inspire the application of the OPLS-L force field in the simulations concerning mixed polyolefin.

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