Silane Cross-linking With Synergistic Flame Retardant Research On Polyolefin Cables

Silane cross-linked polyolefins are widely used in wire and cable because of their good mechanical properties,processability,heat resistance and electrical insulation properties.However,their low oxygen index and flammability limit the application range.Therefore,the research on the flame retardant of silane cross-linked polyolefins has become a trend of development.Based on this,a kind of high efficiency and low filling halogen-free flame-retardant was developed by compounding hydroxide flame retardants and co-efficient flame retardants in this article,it layed a good foundation for industrialization of silane cross-linked polyolefin cable material.In this paper,the preparation process and formulation of silane cross-linked polyolefins were confirmed by orthogonal test,and silane cross-linked flame retardant polyolefin composites were prepared by two-step method.Firstly,the optimal ratio of ATH and MH flame retardants was explored,and the influence of oxygenation index,mechanical and electrical properties and workability before and after the coupling treatment were investigated.The results showed that the coupling treatment improved the workability of the composites.Compared with the untreated composites,the tensile strength,elongation at break,volume resistivity and breakdown field strength were all improved.The weight ratio of ATH to MH was determined to be ATH:MH=20:40.Secondly,the cross-linking time and the cross-linking temperature of the composites were determined.The results showed that the best properties of the composites were obtained when the cross-linking temperature was 80 ? and the cross-linking time was 8 h.The effects of OMMT,ADP and ZB on the cross-linking degree,flame retardancy,thermal stability,mechanical properties and electrical properties and processability were studied.The results showed that: 1)adding proper amount of OMMT could improve the processability of the composite material andenhance the thermal stability of the material.When the content of OMMT was 5wt%,the surface of the composites was smooth,the elongation reached 15 %,the permanent deformation rate reached 6.6 %,the oxygen index reached 34 %,the thermal carbon residue rate was 38.3 %,the tensile strength reached 14.86 MPa,The elongation at break reached 378.9 %,the breakdown field strength was 22 MV/m and the volume resistivity was 2.96×1013 ?·m.2)The appropriate amount of co-efficient flame retardant ADP added to help improve the workability of the composite material.When the content of ADP was 3 wt%,the properties of the material reached the best.The hot-stretch elongation was 17 %,the permanent deformation was 13.3 %,the oxygen index was 33 %,the elongation at break was 364.79 % and the tensile strength was 14.6 MPa.The volume resistivity was 1.98×1013 ?·m and the breakdown field strength was21.6 MV/m.3)ZB as a synergistic flame retardant could improve the workability of the composites and improve the thermal stability of the composites.When the content of ZB is 6 wt%,the properties of the material were balanced.The elongation were 17 %,the permanent deformation rate was13.3 %,the oxygen index was 33 %,the residual carbon rate was 39.8 %,the tensile strength was 13.6 MPa,the elongation at break The rate was 341.68 %,the volume resistivity reached 2.05×1013 ?·m,and the breakdown field reached21.4 MV/m.Finally,the effect of co-efficient flame retardants on the amount of hydroxide flame retardants was also discussed and the amount of flame retardant masterbatches was determined.The results showed that the use of coefficient flame retardants can effectively help the performance of ATH and MH reduced from 51 wt% to 36 wt%,the optimal amount of flame retardant masterbatch should be 60 wt%.