Wide- and small-angle X-ray scattering studies on the deformation behaviour of poly(ethylene terephthalate)

In this study the microscopic deformation behaviour of amorphous PET during uniaxial tensile tests at room temperature was investigated by in-situ wide- and small-angle X-ray scattering using synchrotron radiation. WAXD patterns of deformed PET show a highly orientated amorphous halo and no significant crystallization was found. SAXS patterns of the slowest drawn samples show typical craze like patterns, which finally evolve in elliptically shaped patterns, indicating micro voiding. At higher draw rates the formation of fibrils is not observed and the material directly cavitates. This micro voiding phenomenon causes whitening of the deformed PET