AbstractStress–strain relationships are calculated for three models of the deformation of monocrystalline polytetrafluoroethylene,\documentclass{article}\pagestyle{empty}\begin{document}$ \rlap{--} ({\rm CF}_{\rm 2} \rlap{--} )_n $\end{document}. The physical models comprise either sliding one molecule or one plane of molecules parallel to the molecular chain axis past its stationary neighbors. The potential energy is calculated for each stage of deformation by semiempirical methods by use of 6‐exp and dipole–dipole interactions. Application of Eyring's activated complex theory leads to stress–strain relationships. These are compared with results of friction measurements