Abstract: Halogen-free flame-retarded EVA composites were prepared in a melt process using hydromagnesite as inorganic flame retardant filler which was modified with the silane coupling agent SCA-1113 and alu minate coupling agent F-2 in this article .The effects of SCA-1113,F-2 and SCA-1113/F-2 on mechanical properties and flame retardant properties of the hydromagnestie/EVA composites had been studied ,while the mechanism of surface modification and micro-structure of the hydromagneste/EVA composites was investigated using the FTIR spectra and SEM image respectively as well .The results showed that three kinds of surface modifier formulations could improve the flame retardant properties of the composites ,the oxygen index was increased by 1.6%to 1.9%,UL-94 level was raised to V-0 level;1.5wt%SCA-1113/F-2( mass ratio of the two surface modifiers was 1∶2) made the tensile strength and elongation at break of composites increase to 9.50 MPa and 176.02% respectively; FTIR spectra showed that the surface modifier molecules of three kinds of surface modifier formulations had formed hydrogen bonding with the powder surface and reacted with the -OH of hydromagnesite;FTIR spectra of powders modified by SCA-1113/F-2 showed that SCA-1113 reacted with F-2 and formed a new type of chemical bond Si-O-Al;SEM image of composite material micro-fracture indicated that three kinds of surface modifier formulations could promote the dispersion of powder in the matrix , the effect of SCA-1113/F-2 was the best .

Key words: hydromagnesite;surface modification;EVA;inorganic flame retardant filler