The Modification Of R-PET By Hydrophilic And Studies On The Preparation And Properties Of Toughened R-PET/PBT Alloy

Poly(ethylene terephthalate) (PET) usually undergoes hydrolysis and thermal degradation during the recycling process and reprocess. These degradation reactions result in rupture of molecular chain, decrease in intrinsic viscosity and mechanical property of PET. Thus, recycle poly(ethylene terephthalate) (R-PET) without modification can only be used in the production of polyester short fiber with low added value. In our previous work, a series of high-performance R-PET blends were obtained by the modification of ADR4370S chain extension, nucleating agents and toughening of ABS using the torque rheometer, which is expected to use in the applications of long fiber-spinning and engineering plastics. On the basis of these work, in this paper, the hydrophilic property of R-PET was improved to broaden its application in long fiber. Secondly, the R-PET was modified by chain extension and reinforcement and toughening for the preparation of high toughness and rigidity R-PET engineering plastics to make high-value use of of the R-PET. The main research contents and results of this paper are as follows:First of all, the HY-3525G, which was a kind of epoxide agent, was employed as a hydrophilic modifier to prepare R-PET/HY-3525G blends by melt banburying reaction. The effects of HY-3525G content on the rheological properties, crystallization properties and hydrophilic properties of the melt blends were investigated. Besides, the R-PET/HY-3525G blends were spined for fiber using fiber production technology. The results showed that the balancing torque of the modified R-PET was decreased with with the increment of HY-3525G contents. However, no significant change in the crystallization temperature and melting temperature was found; compare with the pure R-PET, the contact Angle of the blend was decreased from 95.12° to 63.65° with the addition of 2 wt% of HY-3525G, showing the improvement of hydrophilic of modified polyester fiber.Secondly, the R-PET/ADR4370S blends with various ADR4370S contents were prepared by twin-screw extruder and triple screw extruder. Then, The mechanical properties, microstructure, intrinsic viscosity, flow properties, thermal stability and crystallization property of the blends prepared by these two kinds of process were investigated. The results showed that two kinds of preparation methods can effectively improve the intrinsic viscosity of R-PET through the chain extension modification, and then reduce the crystallization temperature and melting point of R-PET. However, the blends prepared by twin-screw extruder showed better performances in the same case of ADR4370S content. Compared with pure R-PET, the intrinsic viscosity was increased from 0.61 dL/g to 0.85 dL/g with raising the concentration of ADR4370S from 0 to 1 wt%. Besides, the tensile strength and notched impact strength of the R-PET/ADR4370S blends with 1 wt% ADR4370S increased by 207.01% and 72.61%, respectively.Thirdly, The PBT was used as a reinforcing agent to investigate the effects of PBT content on the performance of R-PET/PBT/ADR4370S alloy. The results showed that the addition of PBT significantly affected the melting and crystallization behavior of R-PET/PBT/ADR4370S alloy and improved the compatibility between the two phases, resulting in the decrement of the molecular movement ability for the blends. Compared with pure r-PET, the crystallization properties and mechanical performance of the alloy were enhanced with the addition of 40 wt% of PBT. And the slightly decrease in the crystallization temperature and crystallinity of the alloy was responding to the presence of chain branching.Finally, the nuclear shell structure of MBS was used as a toughening agent to improve the toughness of R-PET/PBT/ADR4370S blends, and the R-PET/PBT/MBS /ADR4370S blends were prepared by melt blending. The effects of MBS contents on the mechanical properties, crystallization behavior and micromorphology of melt blending were investigated. The results illuminated that the storage modulus of the blends decreased with the increment of MBS content. And the MBS had obvious toughening effect on the R-PET/PBT/ADR4370S blends, the notched impact strength of the blends increased from 4.3 to 16.6 kJ/m~2 when the content of MBS was 15 phr.