Study On Properties Of PET/PBE Blends Prepared Under Elongational Flow

Polyethylene terephthalate(PET),has a large annual output volume and low price,with excellent chemical resistance,heat resistance,air tightness,abrasion resistance and electrical properties,and it can maintain higher mechanical strength and dimensional stability over a wide temperature range.Therefore,it is widely used in film,hollow container and fiber.However,poor toughness,insufficient rigidity and slower crystallization rate at normal temperature restrict the application of PET in engineering materials.In order to broaden the application field of PET,modified on PET must be carried out.In order to obtain a PET-based blends with rigid-to-toughness characteristics,a propylene-based elastomer(PBE)was blended with PET,and the PET/PBE blends were prepared via elongational flow extruder and twin-screw extruder.The effects of matrix ratio,compatibilizer type,compatibilizer content and processing flow field on the structure and properties of the blends were investigated.Firstly,the effects of ternary copolymerization reactive elastomer(EGMA)on the structure and properties of PET/PBE blends with different matrix ratio were investigated.The results of contact angle test and spreading coefficient analysis indicated that EGMA was distributed at the PET/PBE interface;The compatibilization reaction between the functional group of the blends was confirmed by infrared spectroscopy;The results of SEM micromorphology showed that adding EGMA can improve the interface adhension effectively within a certain range;DSC thermodynamic behavior analysis results show that EGMA can not only limit the movement of PET molecular chain segments,but also play a plasticizing role in the blend.The formed crystalwith different perfection degree,and the crystallinity decreased.The dynamic rheological behavior analysis showed that the introduction of EGMA could form PET/EGMA copolymer in the system,which improved the complex viscosity and storage modulus at low frequency zone of the blends.The mechanical properties showed that When the PET/PBE ratio is 80/20,a PET/EGMA/PBE ternary blend material with a rigid toughness balance property can be obtained under a elongational flow field.And the impact strength,the tensile strength,tensile modulus and flexural modulus are 35.04 KJ/m~2,36.45Mpa,665.5Mpa and 1757.03Mpa,respectively.increased about 8 times or kept 90%,88%,and 98%in contrast with the PET/PBE binary blend.Next,in order to verify whether other types of compatibilizers in the elongational flow field can also have a good compatibilizing effect on PET/PBE blends,and obtain a blends with rigid and tough balance characteristics.The effects of ethylene acrylic acid copolymer grafted glycidyl methacrylate(EAA-g-GMA)and maleic anhydride grafted propylene-based elastomer(mPBE)on the structure and properties of PET/PBE blends were investigated.The experimental results show that the introduction of EAA-g-GMA and mPBE also can produces the corresponding copolymer at the interface through the compatibilization reaction,which improves the interface adhension of the blends.while limiting the molecular chain segment mobility;DSC crystallization behavior Analysis shows that melting bimodal show up and crystallization enthalpy decreased in the blends,indicating that the mobility of the PET chains of the blends was restricted,and crystals with different perfection degrees were formed.The mechanical properties test results showed that PET/EAA-g-GMA/PBE ternary blends and PET/mPBE/PBE ternary blends have a certain degree of rigid toughness balance property,but under the same ratio,the combined performance of their is not comparable to PET/EGMA/PBE ternary blending.Finally,the PET/EGMA/PBE ternary blends were prepared by twin-screw extruder and compared with the performance of PET/EGMA/PBE ternary blend prepared by elongational rheological extruder.The effect of processing flow fields on the structure and properties of PET/EGMA/PBE ternary blends were investigated.Through comparison of experimental results,it was found that the PET/EGMA/PBE ternary blends prepared under shear flow field have a relative lower rigid toughness balance property compared with the blends prepared under elogational flow field.Further analysis showed that the ternary blends prepared under the shear flow field have a higher debonding rate,dispersed phase particles and the reaction degree was not enough.Therefore,the results of the study indicate that the elongational flow field is more conducive to the dispersion mixing of the blend and promoting the compatibilization reaction.