Addressing diffusion behavior and impact in an epoxy-amine cure system using molecular dynamics simulations

SH Kwon and HS Kang and BJ Kim and HI Lee and JM Lee and J Kim and SG Lee, SCIENTIFIC REPORTS, 13, 138 (2023).

DOI: 10.1038/s41598-022-26835-2

To deepen understanding of diffusion-controlled crosslinking, molecular dynamics (MD) simulations are carried out by taking the diffusion image of 3,3 '-diamino diphenyl sulfone (3,3 '-DDS) and polyethersulfone (PES) with epoxy resin varying temperatures from 393.15 to 473.15 K over crosslinking conversion of 0-85%. The diffusion of PES and 3,3 '-DDS into the bulk increased with increasing the temperature as a result of enhanced mobility of the molecules when the difference between the glass-transition temperature (T-g) and the curing temperature. Beyond the onset points of the converged crosslinking conversion ratio of 3,3 '-DDS and PES, their diffusion properties are obviously restricted with crosslinking conversion ratio. At low crosslinking conversion ratios (> 10%), the diffusion coefficients of triglycidyl p-aminophenol (TGAP) were 1.1 times higher than those of diglycidyl ether of bisphenol F (DGEBF) because of the lower molecular weight of TGAP. On the other hand, the diffusion coefficients of TGAP decreased when the crosslinking ratio was up to similar to 60% because, compared with DGEBF, it had more functional groups available to react with the curing agent. At higher crosslinking ratios, the diffusion coefficients of both resins converged to zero as a result of their highly crosslinked structures.

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