Effect of Heat-Setting Temperature on the Structure and Properties of BOPET Film

In order to clarify the influence of processing parameters on the structure and properties of biaxially oriented polyethylene terephthalate (BOPET) films, by preparing BOPET film using a biaxial stretching film production line, the structures were characterized by means of DSC, WAXD, SAXS and the mechanical, optical, and thermal shrinkage properties were analyzed to investigate the effects of heat-setting temperature on the structure and properties of BOPET films. The results showed that with the increase of heat-setting temperature, the tensile strength in the machine direction (MD) of BOPET film decreased, while the fracture elongation and elastic modulus in the transverse direction (TD) increased. In addition, the crystallinity and long period of BOPET films increased, haze increased, and the transmittance and glossiness showed little change. However, the thermal shrinkage rates in both MD and TD decreased.