Research Of Superfine Magnesium Hydroxide Surface Modification And Its Flame Retardancy In Eva Composite

Halogen-type flame retardants were popular for the excellent flame-retardingefficiency before. Because of their flame toxicity and the release of toxic gas andsmoke of flame-retarded composites once they are heated and fired, they are bannedin some situation. Therefore, alternative halogen-free flame retardants especiallymagnesium hydroxide (MH) have attracted great attention of researchers. However,to be efficacious, higher loading of MH is significantly necessary. To endowMH/Polymer composites with excellent flame retardancy, the filling level of MH isusually required reach up to over50wt.%in total, which easily results in processingdifficulties and marked deterioration in mechanical performances due to poorinterfacial adhesion between MH and polymer. It is essential to render the surface ofMH filler and polymer compatible, and this aim can be achieved via surfacemodification of MH powders. Nowadays the surface modification of MH powdersmainly depends on experience in industry, and the research of how the surfacemodifier reacts on the MH surface is unsystematic. However, the mechanismconsiderably affects the result and cost of modification. Meanwhile, various surfacemodifiers make it difficult to do sufficient research on the surface modification ofMH powders.In this work, we broaden and deepen the research on the modificationmechanism of stearic acid and silane coupling agent, the most frequently usedsurface modifiers for MH. Firstly, choosing stearic acid to modify MH thoughultrasonic-assisted wet method, the FT-IR, TGA, XRD and SEM have beencombined to analyze the modification mechanism, and the result shows that surfacesaturation exists during the modification process. Moreover, the surface of MH ismodified with Trimethoxy[3-(phenylamino)propyl]silane(Y-9669). The modificationmechanism is analyzed by SEM, TGA-DSC and FT-IR. The results show thatsiloxane structure grafts onto the surface of MH, and the optimal dosage of silane is1.5wt.%. In addition, MH/ethylene-vinyl acetate copolymer(EVA)(1:1) composites are also prepared. The tensile strength of silane modified MH/EVAcomposite(10.48Mpa) is about200%to that of MH/EVA composite, and theelongation at break of silane modified MH/EVA composite(267.31%) is about370%to that of MH/EVA composite, while the flame retardancy of both composites arealmost the same.In conclusion, this work not only brings some useful information for the surfacemodification research, but also gives some suggestions for the surface modificationof MH powders in industry.