Effect of chemical structure on thermo-mechanical properties of epoxy polymers: Comparison of accelerated ReaxFF simulations and experiments. (5th December 2018)

• Record Type: Journal Article
• Authors: Vashisth, Aniruddh; Ashraf, Chowdhury; Bakis, Charles E.; van Duin, Adri C.T.
• Is Part Of: Polymer. Volume 158(2018)
• Page Start: 354
• Page End: 363
• Publication Date: 2018-12-05
• Subjects: Molecular dynamics -- ReaxFF -- Simulations; Polymers -- Periodicals; Polymerization -- Periodicals; Polymères -- Périodiques; Polymérisation -- Périodiques; 547.7
• DOI: 10.1016/j.polymer.2018.11.005
• Languages: English
• ISSNs: 0032-3861

Abstract

Abstract: Chemical structure governs the bulk material properties of thermoset polymers at the macro-scale. In this study, three different amine curing agents — aromatic, cyclo-aliphatic and aliphatic — are reacted with bisphenol-A epoxide using a recently developed accelerated ReaxFF simulation approach for kinetically slow reactions. Accelerated ReaxFF simulations provide reactants with energy (comparable to the barrier energy) to form a stable transition state that, depending upon the proximity and the path of approach, leads to successful cross-linking. While cyclic curing agents result in simulated polymers with local heterogeneities in the molecular structure that can be resolved by annealing, strain rate dependence is manifested prominently in polymers with aliphatic curing agents and less prominent in polymer with aromatic curing agent. Based on the good correlation obtained between simulations and experiments, this work demonstrates that accelerated cross-linking and virtual testing of the polymer can capture the translation of variable chemical structure to thermo-mechanical properties of thermosets. Graphical abstract: Highlights: Accelerated reactive molecular dynamics simulations for kinetically slow reactions to examine crosslinking in epoxies with different amines. The method was able to simulate crosslinking of bisphenol-A epoxide with three different amine curing agents. Thermo-mechanical properties of simulated polymers show agreement with experimental results. Cyclic curing agents show higher local heterogeneities, while strain rate dependence is manifested prominently in aliphatic curing agents.