Using molecular dynamics simulations, we show that a widely accepted theoretical prediction for glassy-polymeric strain-hardening moduli ($G_R\propto {\rho }_e$, where ${\rho }_e$ is the entanglement density) fails badly for semiflexible polymers. By postulating that the length, energy, and strain scales controlling $G_R$ are the Kuhn length ${\ell }_K$ and statistical-segment length $b=\sqrt{{\ell }_0{\ell }_K}$ (where ${\ell }_0$ is the backbone bond length), the intermonomer binding energy $u_0$, and the incremental elastic strain ${\mathcal{S}}_{\mathrm{c}}$ required to activate Kuhn-segment-scale plastic rearrangements, we develop a scaling theory predicting that $G_R={\mathcal{S}}_{\mathrm{c}}(u_0/{\ell }_0^3){(b/{\ell }_0)}^3$ in the athermal limit. This prediction agrees quantitatively with the simulated $G_R$ values for athermal uniaxial-stress extension, and semiquantitatively with the values for athermal constant-volume simple shear, for bead-spring polymer glasses spanning a range of ${\ell }_K/{\ell }_0$ that is wider than the range spanned by real systems.

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• Plastic deformation
• Polymer glasses
• Molecular dynamics
• Polymer scaling theory