Temperature dependent network properties of amorphous PCT during tensile stretching

Tensile deformation behavior of amorphous Poly (1,4-cyclohexylenedimethylene Terephthalate) (PCT) at 25 °C–108 °C was investigated by means of in situ synchrotron wide-angle X-ray scattering (WAXS). WAXS patterns were processed in a way that the scatterings from isotropic and anisotropic structures were separated. It turned out that the influences of temperature during deformation can be divided into three zones: below 80 °C, only molecular chains oriented; between 80 °C to 90 °C, very few imperfect crystals were induced by strain; above glass transition temperature (92 °C), the triclinic PCT crystalline structure began to form during deformation process. It was found that the Gaussian model of Haward and Thackray described the stress-strain behavior of the tensile stretched amorphous PCT very well. However, when being stretched above 80 °C, the system showed two characteristic network moduli because of strain-induced crystallization. The onset of change in network modulus occurred immediately after the formation of unoriented crystallites which served as physical cross-linking points to reinforce the material.