Preparation Of UV-Grafted Polyethylene Grafted Maleic Anhydride And The Research On Its Photochemical Principle

When the polyethylene molecular chain is grafted with maleic anhydride molecules,the adhesion of the surface of the polyethylene molecule can be significantly improved,and at the same time,since the maleic anhydride molecular group introduced in the polyethylene molecular chain belongs to a polar group,The affinity of the polyethylene molecule with other materials can be improved.In addition,polyethylene grafted with maleic anhydride greatly improved the space charge inhibition characteristics of pure polyethylene.The grafting reaction by ultraviolet light irradiation can effectively avoid cross-linking of polyethylene molecules and achieve low gel grafting reaction.In this paper,three sets of experiments were designed with UV irradiation time,maleic anhydride monomer concentration and photoinitiator benzophenone concentration as variables to prepare and purify the graft.The grafting rate and gel content of the grafts were determined.The results showed that the grafting ratio could reach the expected value at the current research level,and the gel content of the grafted sheet was very low,close to zero gel.The infrared spectrum was measured after secondary compression of the material without ultraviolet irradiation,and the infrared spectrum showed that only a small amount of maleic anhydride remained,and the ultraviolet-ray irradiated sheet was purified and subjected to infrared spectroscopy.Measurement,the spectrum shows that the absorption peak is very strong,and the position of the absorption peak coincides with the rotation and vibration peak of the acid anhydride molecule,indicating that the grafting is successful.The grafts were tested for dielectric constant and dielectric loss and compared with LDPE.The results show that the dielectric constant of the graft increases,and the dielectric loss of the graft at low frequency is higher than that of LDPE.However,when the frequency is lower than 10^-1Hz,the dielectric loss of the graft begins to stop increasing and decreasing.The dielectric loss of the lower graft increases slowly and is lower than that of LDPE.Then,the electrical conductivity characteristics of the graft and LDPE at room temperature and 50°C were measured.The results show that the trend of the electrical conductivity characteristics of the graft and LDPE is basically the same,but the overall electrical conductivity is smaller than that of LDPE.Secondly,the graft breakdown was tested by DC breakdown field strength and compared with LDPE.The results show that the breakdown field strength of the graft is significantly improved compared with LDPE,and the introduction of maleic anhydride molecules can significantly improve the breakdown performance of LDPE.Finally,the space charge distribution of the graft was determined and compared with LDPE.The results show that the peak charge of the space charge is significantly reduced and the space charge distribution is significantly improved.