Studies On Compatible Modification Of R-PET/SEEPS、r-PET/PP Blends And The Crystallization Behavior Of PET

First of all, styrene-[ethylene-(ethylene-propylene)]-styrene block copolymer (SEEPS) was employed as a toughener to toughen recycled poly(ethylene terephthalate)(r-PET) by melt blending in this article. The rheological behavior and compatibility of the r-PET/SEEPS blends were investigated by dynamic rheometer and dynamic mechanical thermal analysis (DMA), etc. Besides, the mechanical properties of the blends were also tested. The results showed that the r-PET and SEEPS exhibited a poor compatibility. The complex viscosity and elastic modulus of the r-PET/SEEPS blends increased with the increment of SEEPS contents, indicating the entanglement between the r-PET and SEEPS. The blends exhibited a typical shear thinning behavior. However, raising SEEPS concentration decreased the internal friction peak of the blends. The results of mechanical properties testing showed that the notched impact strength of the r-PET/SEEPS blends with the addition of20wt%of SEEPS increased by107.04%in comparison with pure r-PET, and the flexibility increased obviously, whereas the flexural strength decreased slightly.Secondly, the SEBS-g-MAH was used as a compatibilizer to improve the compatibility of r-PET/SEEPS blends, and the r-PET/SEEPS/SEBS-g-MAH blends were prepared by melt blending. The compatibilizing effects of SEBS-g-MAH on the r-PET/SEEPS blends were investigated by dynamic rheometer, scanning electron microscope (SEM) and differential scanning calorimeter (DSC). The results showed that the addition of SEBS-g-MAH increased the interfacial interactions and improved the compatibility between the two phases, resulting in the decrement of the dispersed phase size for the blends. Compared with pure r-PET and the uncompatibilized r-PET/SEEPS blends, the notched impact strength of the r-PET/SEEPS blends with10%SEBS-g-MAH increased by209.51%and80.86%, respectively.Thirdly, the self-made glycidyl methacrylate/styrene multi-monomer melt grafting ethylene-octene block copolymer (OBC-g-(GMA-co-St)) and commercial maleic anhydride grafting ethylene-octene copolymer (POE-g-MAH) were used to compatibilize the r-PET/PP blends. The results showed that both the (OBC-g-(GMA-co-St)) and POE-g-MAH had compatibilizing effects on r-PET/PP blends. The addition of the two types of compatibilizer could decrease the size of the dispersed phases and significantly increase the notched impact strength, complex viscosity, storage modulus and loss modulus of the blends. In addition, the crystallization of the r-PET and PP in the blends was inhibited by the addition of OBC-g-(GMA-co-St).Finally, the PET/mica and PET/TiO2-coated mica composites were prepared by melt blending using mica and self-made TiO2-coated mica as nucleating agents. The comparison of the effect of two nucleating agents on the crystallization behaviors and non-isothermal crystallization kinetics of PET were investigated. The results showed that both mica and TiO2-coated mica could acte as the heterogeneous nucleating agent to improve the crystallization properties of PET and accelerate its crystallization rates. The Jeziorny equation and Ozawa equation failed to describe the non-isothermal crystallization process for PET, PET/mica and PET/TiO2-coated mica composites, while the Mo model provided a good fitting. In addition, both the mica and Ti02-coated mica could facilitate the crystallization of PET, and the existence of TiO2-coated mica was more favorable for the crystallization of PET.