The Work of Mechanical Degradation in Elongating Polymer Melts

Journal Article · 13 February 2025 · Macromolecules

DOI: https://doi.org/10.1021/acs.macromol.4c02063 · OSTI ID:2519044

Chongvimansin, Nattavipa ^[1]; O’Connor, Thomas C.  ^[1]

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1. Carnegie Mellon University, Pittsburgh, PA (United States)

Molecular dynamics simulations are used to study the mechanical degradation of well-entangled polymer melts during uniaxial extensional flow. Simulations measure the transient rise in extensional stresses and relate them to the molecular alignment and scission of chain backbones. Intermolecular entanglements couple chain scission in space and time, making degradation sensitive to deformation history and strain rate in ways not displayed by dilute polymer solutions. The rate of chain scission is nonmonotonic and peaks at strains corresponding to the maximum extensibility of entanglement segments but prior to the full extension of chain backbones. We measure a specific work per scission event w* and decompose it into separate contributions associated with chain alignment, chemical bond breaking, and scission-induced plasticity. We find chain scission in melts requires activating plastic dissipation that is multiple orders of magnitude larger than the chemical work required to break a covalent backbone bond. Our findings underscore the critical need to consider bulk polymer mechanics and rheology in designing efficient mechanical degradation and mechanochemical processes.

• Research Organization: Carnegie Mellon University, Pittsburgh, PA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: SC0025643
• OSTI ID: 2519044
• Journal Information: Macromolecules, Journal Name: Macromolecules Journal Issue: 4 Vol. 58; ISSN 0024-9297
• Publisher: American Chemical SocietyCopyright Statement
• Country of Publication: United States
• Language: English