In this research, PET filaments were drawn with different draw ratios at 80?C to obtain filaments with different structures. Formation of mesophase structure was investigated by different techniques such as Wide Angle X-ray Scattering (WAXS), Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC), Dynamic Thermal Mechanical Analysis (DMTA), density measurements, thermal shrinkage, mechanical properties and birefringence. Our results showed that the drawing process increased the ratio of oriented amorphous regions. As a result, it seems that drawing of poly(ethylene terephthalate) filaments at near glass transition temperature caused formation of an intermediate structure in the filaments with the characteristic of extended chains in the non-crystalline regions and formation of small folded chains crystallites. On the basis of these observations, some schematic models were proposed for the structure of the poly(ethylene terephthalate) filaments drawn at near glass transition temperature range.
