Tensile deformation of polychlorotrifluoroethylene in He,N2, Ar,O2, and CO2 environments

The tensile stress—strain behaviour of quenched polychlorotrifluoroethylene (PCTFE) was measured from 77K to T_g in gaseous environments of He, N₂, Ar, O₂, and CO₂ and in water. The partial pressure of the gas was varied from 0 to 1 atm. N₂, Ar, O₂ and CO₂ produced crazing and a lowering of the tensile strength relative to the intrinsic tensile strength at that temperature. The effect of pressure and temperature on the tensile strength was quantitatively similar to the effect of these gases on PC and PMMA, and could be described by an equation of the form: $\text{σ}{}_{\mathrm{c}}\text{σ}{}_{\mathrm{i}}\text{= P}\text{exp}\text{(}\text{Q}\text{RT}\text{/P1]}{}^{\mathrm{?0.10}}$. The constants Q and $\text{P1}$ depended on the gas, and σ_i is the intrinsic strength. The Q values were approximately the same as the heat of vaporization for each gas. CO₂ produces crazing below as well as above its sublimation temperature. The intrinsic yield point varied from 0.033 to 0.054 of E, Young's modulus, as the temperature varied from 300 to 77K. The experimental value of the yield point extrapolated to 0.055E at OK and compares favourably with existing theories for the yield point of glassy polymers.