Influence of transesterification on the properties of PET/MAPE blends prepared by reactive extrusion

Blends based on maleic anhydride grafted polyethylene (MAPE) and poly(ethylene terephthalate)(PET) were prepared through reactive extrusion in the presence of titanium tetrabutoxide (Ti(OBu)4) as transesterification catalyst. Mechanical properties of PET/MAPE blends(70wt./30wt.) were evaluated by mechanical tests. The Effects of Ti(OBu)4 on the structure and melt crystallization behavior of the blends were investigated by Fourier transform infrared spectroscopy(FTIR), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The addition of Ti(OBu)4 to the blends could improve the compatibility between PET and MAPE as was evidenced by the SEM micrograph in which filaments connected to a network structure was observed. With increasing the contents of Ti(OBu)4, the impact strength of the blends increased obviously, the flexural strength and tensile strength of blends did not change significantly, while the degradation of PET was gradually significant as was evidenced by FTIR analysis. Small amount of Ti(OBu)4 could hinder the crystallization of PET and make its melt peak shifted to higher temperature.