| Poly (ethylene terephthalate)(PET) is widely used in the fields of fiber, film and soft bottle industry because of its excellent properties on electrical insulating, heat and chemical resistance. In order to exploit its new application fields and improve its additional value as engineering plastic, the crystallization behavior and the mechanical properties of PET have to be improved. In this work, we studied PET and its composites on its crystallization and rheology behavior, chain extention, strength and toughness improvement, etc.Effects of nucleating agents, including sodium benzoate, alkyl (C28-C32) carboxpylic salt and ionomer Surlyn on non-isothermal crystallization kinetics of PET were also studied in this work by means of differential scanning calorimetry(DSC). The parameters of non-isothermal crystallization kinetics were obtained through Ozawa equation. The results indicated that the inclusion of nucleating agents greatly improved the crystallization behavior. The onset temperature of crystallization shifted to the higher temperature zone, half crystallization time shortened and the crystallization rate increased. Among the three types of nucleating agents, sodium benzoate nucleating agent has the best effect. However, it caused the degradation of PET molecular chain which resulted in the decrease of the intrinsic viscosity of the material. Surlyn has no effect to PET's intrinsic viscosity, and Nav101's effect is in between. As for Surlyn and Nav101, the optimization of nucleating agent's content is 1.0%. When its content is higher than 1.0%, the material's intrinsic viscosity will come down. Meanwhile the crystallization behavior will not be enhanced anymore, but decrease.We also studied the relationship of crystallization behavior with intrinsic viscosity of PET/Sodium benzoate/chain extender RA20. Although sodium benzoate is one of the most effective nucleating agents, it will cause degradation of PET chain and deteriorate its performance. In order to restrain the negative function of sodium benzoate, we selected a chain extender of multi-functional groups - RA20 to enhance the molecular weight of PET and improve the material's mechanical properties. As a result, the intrinsic viscosity of PET/sodium benzoate/RA20 was enhanced with the increase of RA20. What's promising is that when the content of RA20 was kept below 2%, it will not do harm to the crystallization behavior of the composites, but will enhance its crystallization rate. When RA20's content exceeds 3%, the increasing of PET/sodium benzoate's intrinsic viscosity becomes slow. Meanwhile the nucleating ability of PET/sodium benzoate was declined and the crystallization peak was widened and crystallization rate was lowered. The present work also aims at improving the toughness of Poly (ethylene terephthalate)(PET)/glass fibers (GF) blends through the addition of ethylene-butylacrylate-glycidylmethacrylate copolymer (EBAGMA) and maleic anhydride grafted polyethylene-octene (POE-g-MAH) individually. The morphology and mechanical properties of the ternary blend were studied in detail. It was found that EBAGMA was more effective in toughening PET/GF blends than POE-g-MAH due to its better compatibility with PET and stronger fiber/matrix bonding, indicated from SEM images. As a result, PET/GF /EBAGMA ternary blend has improved impact strength and well balanced mechanical properties at a loading of 8wt% EBAGMA. The addition of POE-g-MAH weakened the fiber/matrix bonding due to more POE-g-MAH coated on the glass fiber, leading to lowered impact strength, tensile strength and flexural modulus. According to dynamic rheometer test, both EBAGMA and POE-g-MAH remarkably increased the melt storage modulus and dynamic viscosity. DSC analysis showed that the addition of EBAGMA lowered the crystallization rate of PET/GF blend, whereas POE-g-MAH promoted it.Poly(ethylene terephthalate) (PET) was also modified by glass fibers (GF) and EBAGMA. The dynamic rheologic behaviors of PET, PET-GF and PET-GF-EBAGMA blends were studied with an ARES Rheometer. The variations of storage modulus(G′), loss modulus (G″), loss factor (tanδ) and dynamic viscosity (h) with angular frequency (ω) were investigated. The results showed that G′of PET was lower than G″, which resulted from the slippage of molecular chain. The G′and G″were both increased when GF was introduced. Its contribution to G′was a little higher than to G″. Meanwhile tanδwas decreased and h was increased. Further introduction of EBAGMA can also improved the G′and G″of PET-GF simultaneously, but its effect on G′was far higher than on G″. A small content of EBAMGA can decrease PET-GF melt's tanδvery effectively, which indicated that percentage of elasticity distortion in melt distortion was increased. At the same time, h, especially at the lower frequency, increased remarkably.
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