Using molecular dynamics simulations, we show semiflexible bead−spring polymer glasses’ craze extension ratio λ_craze >~ sqrt(N_e/sqrt(C_∞)) , where N_e is their entanglement length and C_∞ is their Flory characteristic ratio, over the entire range of chain stiffnesses for which their parent melts remain isotropic (1 ≤ N_e/C_∞ ≲ 28). Kramer’s classic prediction λ_craze = sqrt(N_e/C_∞) qualitatively captures trends for flexible chains with small C_∞, but quantitatively fails badly over the entire range of N_e/C_∞ studied here because it incorrectly treats Kuhn segments as rigid and inextensible. As a consequence, polymer glasses with N_e/C_∞ all the way down to the lower bound set by the onset of nematic order (N_e/C_∞ = 1) can exhibit a stable craze drawing and a ductile mechanical response.
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