Study On Modification Method And Dielectric Properties Of Polypropylenebased Cable Insulation Material

Cross-linked polyethylene cable insulation material is to form a three-dimensional network structure of macromolecular chains through cross-linking to improve its dielectric properties at high temperatures.However,cross-linking also changes polyethylene from a thermoplastic material to a thermosetting material,which cannot be recycled and reused,contrary to the concept of green environmental protection.The research and development of thermoplastic cable insulation materials has become a hot spot recently.Thermoplastic polypropylene has a higher melting temperature and excellent electrical properties,but it is prone to brittle fracture,which is not conducive to the production,laying and installation of power cables.The blending of elastomers can significantly improve the toughness of polypropylene materials,but the dielectric properties of the materials have dropped significantly.The technical difficulty is that it is difficult to improve the mechanical and electrical properties in the same direction.The key to breaking through this bottleneck is to clarify the mechanical and electrical properties inner mechanism.Polypropylene matrix composite crystal structure is susceptible to processing and many factors affecting dielectric properties.In the process flow and formulation system,the processing time and temperature of the material,the use of antioxidant additives,the type and amount of elastomer,and the filling of electrical performance enhancement fillers are involved.Factors such as quantity and dispersibility,their effects on the crystallization and trap characteristics of the material are unknown,resulting in an unknown method for the effective improvement of the dielectric properties and control methods.In this paper,polypropylene is used as the matrix resin,the elastomer is used as the toughening filler,and the nanoparticles are used as the dielectric property improvement filler,and a cable insulation material with excellent mechanical physical properties and dielectric properties is prepared.Many factors involved in the production process of the material are separated layer by layer,and the influence rules and related mechanisms between the crystal morphology,trap distribution and macroscopic electrical properties are explored.In order to meet the dispersion effect of the elastomer and nanofiller in the polypropylene composite material,it is necessary to ensure that the material can withstand the processing for a long time.By changing the blending time and adding antioxidants to explore the properties of polypropylene,the study found that polypropylene blending process will not only reduce its mechanical and physical properties,but also significantly reduce its electrical properties,by adding antioxidants can be effective It can alleviate the thermal oxygen degradation of polypropylene during the blending process,and significantly slow down the mechanical and electrical properties of polypropylene.Through the preparation of PP/SEBS blend materials,it was found that the elastomer SEBS was evenly dispersed in the PP phase of the�sea�shape in the form of�islands�.The dynamic thermomechanical test results showed that the storage modulus of the PP/SEBS blend material was significantly reduced.The storage modulus of SEBS 25%of the blended material at 25?is reduced to 55%of the polypropylene material,indicating that SEBS can achieve the effect of toughening polypropylene.The study found that the PP/SEBS blend material has better water tree resistance than LDPE,because the PP/SEBS blend material has higher crystallinity and stronger anti-slip capability between platelets.At the same time,it was found that the AC and DC breakdown strength of the PP/SEBS blend material was reduced,and the space charge was more than the polypropylene material.By changing the preparation process and regulating the dispersion state of nanoparticles in PP phase and SEBS phase,the study found that nanocomposites can improve the AC and DC resistance of PP/SEBS blend materials on the basis of maintaining toughness and higher melting temperature.Intensity and reduce its space charge accumulation.When most of the nano-Si O₂particles are evenly dispersed in the PP phase region,they show higher AC and DC breakdown field strength and less space charge accumulation,indicating that this preparation method can achieve the same direction to improve the mechanical and physical properties of polypropylene And dielectric properties.Different processing time and the addition of antioxidants increase the space charge accumulation inside the PP sample.After blending SEBS and PP,the current release peak of the TSDC curve increases and moves to the low temperature direction,increasing the trap density of the blended material.After the introduction of nano-Si O₂particles,the inherent charge release peak of polypropylene was completely suppressed.During the linear heating to the melting temperature of PP,there was no charge release peak in the nanocomposite system,indicating that the deep trap level introduced by the nanoparticles is deep enough to ensure The composite system still has space charge suppression capability under high temperature environment.When more nano-Si O₂particles are uniformly dispersed in the PP phase region,the more space charge accumulation can be suppressed.