Research On Preparation And Properties Of Ceramicized Polyolefin Composites

With a large number of underground cables being put into use in cities in China,the situation of laying multiple voltage grade cables in the same cable channel is increasing day by day,and the incidence of fire accidents in China is rising sharply.Once the fire occurs,it will cause huge economic losses.New fire prevention materials are mainly ceramic polymer materials,ceramic silicone rubber is widely used at present,but its cost is high and easy to cause secondary damage and other shortcomings,which forces people to tend to the development of ceramic polyolefin.This study adopts the method of melt blending was prepared by the polyolefin composite ceramic material of ceramics was determined by the control of the single variable method of polyolefin formula system,further research into ceramic packing,flux and the dosage of the flame retardant mechanical properties,electrical properties of the composites and the influence of combustion performance,and analyzed the sintering ceramic vitrified effect,The fire retardant mechanism of ceramicized polyolefin was studied from various angles.The mechanical properties of ceramic polyolefin were tested and the effects of ceramic filler and flux on the mechanical properties of composites were studied.The results show that the mechanical properties of composites are closely related to the amount of porcelain forming additives.A small amount of ceramic powder and glass powder can be evenly dispersed in the matrix to compensate for the gap between fillers,enhancing the intermolecular interaction force and increasing the tensile strength of the composite,but too much filler will appear agglomeration phenomenon,increase the internal defects of the material,causing the decline of tensile strength.The decrease of elongation at break and fracture energy is because the addition of ceramic powder and glass powder restricts the molecular chain movement of matrix.The electrical properties of ceramized polyolefin were characterized by volume resistivity and breakdown field strength.The results show that the addition of inorganic filler has little effect on the volume resistivity of the composites.The addition of a small amount of glass powder improves the volume resistivity and breakdown field strength of the material,but the glass powder itself contains metal oxide,a large number of use will increase the number of carriers and reduce the electrical properties of the material.A small amount of ceramic powder can be evenly dispersed in the matrix to make up for some defects,which makes it difficult to move the carriers inside the material and improve the electrical properties of the material.However,excessive ceramic powder will act as impurities and reduce the breakdown field strength of the material.The compatibility between Mg（OH）₂ and matrix resin is poor.When Mg（OH）₂ is used too much,the interface defects between Mg（OH）₂ and matrix resin will be increased,which will increase the number of conductive particles and cause the decrease of electrical properties of materials.Zinc borate itself contains water of crystal,under the action of electric field will ionize H⁺and OH^-to increase the carrier concentration,reduce the volume resistivity of composite and breakdown field strength.The thermogravimetric analysis,conical calorimetric analysis and macroscopic morphology analysis of ceramic polyolefin show that the addition of ceramic filler,flux and flame retardant is beneficial to improve the combustion performance of the composites.The addition of ceramic powder and glass powder reduces the total amount of heat release and smoke generation,improves the mass retention rate of combustion residues,and reduces the risk of fire.The ceramic body sintered at high temperature has a certain self-supporting ability.With the increase of the amount of ceramic powder and glass powder,the density of ceramic body increases.The addition of zinc borate and Mg（OH）₂can improve the ceramic forming effect,reduce surface cracks and improve the integrity of ceramic body.