Craze Extension Ratio of Semiflexible Polymer Glasses

K Nan and RS Hoy, MACROMOLECULES, 56, 8369-8375 (2023).

DOI: 10.1021/acs.macromol.3c01608

Using molecular dynamics simulations, we show semiflexible bead- spring polymer glasses' craze extension ratio lambda(craze) (N-e/ root C-infinity)(1/2), where N-e is their entanglement length and C-infinity is their Flory characteristic ratio, over the entire range of chain stiffnesses for which their parent melts remain isotropic (1 <= Ne/C-infinity less than or similar to 28). Kramer's classic prediction lambda(craze) = root N-e/C-infinity qualitatively captures trends for flexible chains with small C-infinity, but quantitatively fails badly over the entire range of N-e/C-infinity studied here because it incorrectly treats Kuhn segments as rigid and inextensible. As a consequence, polymer glasses with Ne/C infinity all the way down to the lower bound set by the onset of nematic order (N-e/C-infinity = 1) can exhibit a stable craze drawing and a ductile mechanical response.

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