Function Of Eva In The Highly Filled Applications In The Halogen-free Flame Retardant Lldpe

Peroxide acted as the initiators, maleic anhydride(MAH) grafted ethylene vinylacetate copolymer(EVA) was prepared by melt extrusion process. The effects of differentkinds of initiators, dosages of monomer and processing technology on grafting degreeand melt flow ratio were discussed. Non-halogen flame-retarding materials was preparedfrom linear low density polyethylene(LLDPE) and inorganic flame retardant Mg(OH)2dilled with silane coupling agent and maleic anhydride grafted ethylene vinyl acetatecopolymer used as polymeric compatibilizer. The influence of Mg(OH)2,silane couplingagent and maleic anhydride grafted ethylene vinyl acetate addition level on the propertiesof the composites were studied. The mechanical properties and the oxygen index of thenon-halogen flame-retarding materials were determined. The dispersion andcompatibilization of the Mg(OH)2 in LLDPE were characterized using SEM. The resultsare as following:1. Initiator of A is more effective than initiators of DCP and BPO in the graftingreaction.2.The reaction of EVA copolymer and MAH were carried out at 190℃ to 205℃.Departing ratio of initiator become lower when the reaction temperature is too low, sothat the grafting degree of the product will be cut down. When the temperature is toohigh, the graft ratio will be cut down because of the loss of MAH and the increasing ofthe vice-reaction. Screw rotation at 240r/min in twin-screw extruder is perfect inaccording to grafting degree and product efficient.3. Initiator of A content is more appropriate between 0.06 percent to 0.12 percentwhen the MAH content is stationary. With the increasing of initiator content the degree ofgrafting becomes higher and the melt flow rate decreases. MAH content is moreappropriate between 0.8 to 1.4 percent. The experiment indicates that the more MAHcontent is, the higher graft ratio is. The tendency of graft ratio will be gentle when MAHcontent reaches a certain point. But the melt flow rate goes up with the increasing ofMAH content.4. The materials with good flame retardance could be made with plenty of Mg(OH)2.OI of the composites filled with Mg(OH)2 130 is up to 27 .Amount of Mg(OH)2destroyed the mechanical performances and processing properties of materialsdramatically.5. Silane coupling agent can improve the impact strength and elongation at break ofthe composites. The appropriate dosage of silane coupling agent is 1.2 shares.6. It was found that the EVA-g-MAH increased the interaction between the LLDPEand the flame retardant, and promoted the dispersion of the latter in the former. Theproperties and oxygen index of materials was also improved.7. Comparing EVA-g-MAH /LLDPE/ Mg(OH)2 composites with PE-g-MAH/LLDPE/ Mg(OH)2 composites shows that EVA-g-MAH is a kind of good compatibilizerfor the LLDPE/ Mg(OH)2 composites.