The study of PET/MXD6 blends: Interchange reaction, melting, crystallization, morphology, barrier property and solid state polymerization

The gas barrier properties of Poly (m-xylylenadipamide) (MXD6) are higher than those of Poly (ethylene terephthalate) (PET), therefore, blends of Poly (ethylene terephthalate) (PET) and Poly (m-xylylenadipamide) (MXD6) have been studied, in order to further improve the gas barrier properties of PET resin. Systematic investigations were conducted on PET/MXD6 blends. This research focused on the interchange reaction between PET and MXD6, the melting and crystallization behavior, the solid state polymerization behavior, the strain-induced crystallization, the barrier properties and the morphologies of PET/MXD6 blends.; Results obtained from NMR indicated that there was an interchange reaction between PET and MXD6 in the presence of the catalyst, sodium p-toluenesulfonate. The interchange reaction degree depended on the reaction time, processing temperature, mixing shear rate and the content of catalyst. Without the help of catalyst, the PET did not react with the NLXD6. It has been found that the addition of MXD6 into PET resin can reduce the oxygen permeation rate of blend bottles.; It has also been found that a higher content of catalyst in the blends can act as a crystallization nucleation agent for PET/MXD6 blends. In the process of isothermal crystallization, the nature of the crystallizing component was determined by the content of MXD6 in the blends. If the MXD6 content was lower than 10%, PET was the crystalline phase and the MXD6 remained amorphous. If the MXD6 content was higher than 10%, both PET and MXD6 were the crystalline phases.; The apparent intrinsic viscosity of PET/MXD6 blends depended on the content of MXD6 in the blends. Solid state polymerization was found to further increase the apparent intrinsic viscosity of PET/MXD6 blends. Increased solid state temperatures and times increased the interchange reaction degree between PET and MXD6.; The morphological studies showed that PET/MXD6 blends were two phase systems. PET was the continuous phase and MXD6 was the dispersed phase. The interchange reaction degree can influence the average particle size of MXD6 in the blends. The addition of PET ionomer not only decreased the average particle size of MXD6 in the blends, but also decreased the haze value of PET/MXD6 blend bottles.