The Preparation And Mechanism Research Of Sericite/EPDM Composites

The compatibilization and reinforcement effects of inorganic mineral fillers which were abundant resources and low prices had prompted the application research of inorganic mineral fillers in the field of rubber industry increasingly become a hot topic.For the excellent reinforcing property and high insulation resistance of sericite,this paper modified sericite and filled in EPDM rubber,which was aimed to prepare a kind of composites which had low cost,good performance and could be used in the field of wire and cable.This paper,used sericite in Chuzhou,Anhui Province as the object,systematically researched the surface modification of sericite and the preparation of sericite/EPDM composites,determined the reagent system and modification conditions of sericite and the formulations and vulcanization conditions of ericite/EPDM composites,and analyzed the surface modification mechanism and reinforcing mechanism of sericite by the methods of molecular structure theory,FTIR,SEM,XRD,TG-DSC,etc.The results showed that:（1）The suitable mocification conditions were as following:modifier WD501.5%,modifier WD40 0.5%,diluent ethanol 1.5%,modification temperature 100℃,modification time 20min.The suitable formulations of vulcanization were as following:EPDM 100phr,zinc oxide 4.0phr,stearic acid 1.5phr,coumarone resin9.0phr,antioxidant BHT 1.0phr,accelerant TMTD 0.1phr,accelerant DM 0.3phr,accelerant TRA 0.1phr,modified sericite 40phr,sulfur 1.5phr.The suitable vulcanization conditions were 165℃×12min（2）The tensile strength of sericite/EPDM composites was 10.45MPa,the tensile stress at a definite elongation was 4.04MPa,elongation at break was 989.38%,elongation at a given stress was 31.31%,tear strength was 31.28kN·cm^-1,shore A hardness was 70HA,volume resistivity was 7.87×10⁴M?·km,which had reached the national standards of railway vehicles and cable（wire）that AC rated voltage was 3kV and below,marine electric wire and cable（EPR insulated）that rated voltage was0.6/1kV and below,and the rubber insulated cable that rated voltage was 450/750V and below.（3）The molecular structure theory showed that the modifier hydrolyzed firstly,then condensated and finally adsorbed on the surface of sericite by chemically bonded manner.FTIR analysis showed that chemically bonding formed between modifier and sericite in the modification process and the crosslink bond C-S_X-C formed during vulcanization.The modifier played a“bridge”role in sericite/EPDM composites.SEM analysis showed that the dispersibility and compatibility of sericite in EPDM became better after modification,which increased the internal force of composites.XRD analysis showed that modifier worked on the surface of sericite during modification,while the molecular chains of rubber partially entered the inter-layer structure of sericite when the composites were prepared.TG-DSC analysis showed that the thermal barrier units formed in the rubber matrix after the addtion of sericite,delayed the transfer of heat and improved the thermal stability of composites.And modified sericite had a better thermal barrier effect.