Tensile yield in nylon 6,6

Uniaxial tension tests to, the yield point were performed on poly(hexamethylene adipamide) (nylon 6,6) as a function of temperature from 21 to 200°C at a strain rate of 2 min −1 . At 21 and 60°C, measurements were also made at strain rates from 0.02 to 8 min −1 . Using simple rate theory, reasonable values of activation volume were obtained, but the simple theory is inadequate to determine the activation energy. The yield‐strain temperature dependence changes at 160°C as a result of a reversible crystal‐crystal transition. Because of this behavior of the yield strain, the yield energy is not a linear function of temperature, as observed for several other polymers.