Preparation of Branched and Crosslinked Poly (ethylene terephthalate) and Its Foaming Behavior

The branched and crosslinked poly(ethylene terephthalate)(PET) were prepared by melt-reaction between PET and chain extender poly(butylene terephthalate)-(glycidyl methyacrylate-styrene copolymer)(PBT-GS).During the melting reaction,the change of the torque,the intrinsic viscosity,degree of crosslinking and rheological properties of modified PET were investigated.The modified PET were used to prepare PET foaming materials using supercritical CO₂ as the blowing agent through batch molten-state foaming process.The average cell diameter and cell density of the obtained foaming crosslinked PET were 50-75 μm and 1×10⁸-4×10⁸ cells/cm³,respectively.The influence of foaming temperature and saturation pressure during the foaming process was also investigated.