Preparation Of Epoxy Functionalized Polyethylene And Study On Properties Of PBT

Polybutylene terephthalate(PBT)is one of the five major engineering plastics.It has good chemical resistance,thermal stability and excellent electrical properties.It is widely used in electronic and electrical,auto parts,spinning fibers and other fields.However,due to the low notched impact strength of pure PBT,its application and development in certain fields are limited.Therefore,the toughening modification of PBT materials has always been an important research direction.In this paper,polyethylene grafted glycidyl methacrylate(PE-g-GMA)was prepared by the melting method and used for the toughening modification of PBT and its blends.The mechanical properties,flow properties and microstructure of the blendings were systematically studied.The main research contents and results are as follows:In the experiment of preparing PE-g-GMA,the grafting materials were characterized by infrared spectroscopy,and the effects of the content of GMA and the content of initiator on the grafting rate were investigated,and the grafting rate was calculated by chemical titration.The results show that with the increase of GMA content,the grafting rate of grafts shows an upward trend,but when the GMA content is greater than 4%,the increase of the grafting rate decreases;with the increase of the initiator concentration,the grafting rate first increases and then gradually reduce.GMA and BIPB can achieve the optimal grafting efficiency under the proper proportion relationship.In this group of experiments,when the GMA content is 3%,the BIPB content is 0.2%,that is,when the mass ratio of GMA to BIPB is 15:1,the grafting rate reaches the highest value.In the experiment of toughening PBT,different grafting rates of PE-g-GMA were used to toughen PBT,and the influence of the amount of toughening agent on the properties of PBT was investigated.As the grafting rate of the toughening agent increases,the toughness of the material increases.When the addition amount of toughening agent 3#reaches 15%,the material undergoes a brittle-ductile transition,and the impact strength reaches 35.68 k J/m~2.The DSC test results show that as the content of toughening agent increases,the melting enthalpy and crystallinity of the composite material decrease,the rigidity of the composite material decreases,and the impact toughness increases.The SEM test observed that as the content of the toughening agent increased,the microstructure of PBT was significantly improved,and the toughness of the PBT material was effectively improved.The effects of different grafting ratios of PE-g-GMA,toughening agent content and system phase morphology on the performance of PBT/GF composite system were studied.The mechanical performance test results show that the three kinds of PE-g-GMA with different grafting ratios can effectively improve the impact toughness of PBT/GF composites.The DSC test shows that the crystallization temperature of the composite material has a small decrease,indicating that the self-made toughening agent can effectively maintain the strength of the PBT/GF composite material while improving the toughness of the PBT/GF composite material.SEM test can observe that the introduction of PE-g-GMA improves the adhesion between GF and PBT matrix,thereby improving the toughness of the composite material.The toughening modification of PC/PBT alloy by PE-g-GMA with different grafting rates was studied.The impact strength and elongation at break of PC/PBT alloy increased with the increase of PE-g-GMA grafting rate,and the increase significant,indicating that the increase in the grafting rate can effectively improve the compatibility between PBT and PC.When the grafting rate of the toughening agent is 2.18%,the impact strength of the PC/PBT alloy reaches 58.9k J/m~2,and the impact toughness of the composite material significantly increased.SEM can observe that with the increase of the grafting rate of PE-g-GMA,the fracture holes increase significantly,and the two-phase interface gradually disappears,indicating that the increase in GMA content makes the compatibility between PC and PBT significantly improved,which is beneficial to reduce the interfacial tension and improve the impact toughness of composite materials.