The Preparation Of Modified Magnesium Hydroxide Via In-situ Copolymerization From Phosphate Tailing And Its Study On Flame Retardation Filled Polypropylene

Based on the thorny problem of severe accumulation and environmental hazard of phosphorus tailings,phosphorus tailings was used as materials to prepare nano-magnesium hydroxide(MH)and surface modified MH by in-situ polymerization in this subject.The MH and polypropylene(PP)was physically blended to gain PP/MH composites in different sizes.Then,the products of MH and the composites was systematically characterized and measured by infrared spectrum analysis(FTIR),scanning electron microscope(SEM),transmission electron microscope(TEM),mechanics performance testing,thermo gravimetric analysis(TGA),differential scanning calorimeter(DSC)and melt flow rate(MFR).The conclusions were drawn as following.(1)Used phosphorus tailings as raw materials,the MH products was prepared by acidolysis with sulfuric acid,edulcorating with ammonia and hydrothermal precipitating.The product quality of MH was measured and the microstructure of MH particles was observed by SEM and TEM.The results showed that the MH particles was a flower-like particles.And the MH particles lamella was with a diameter size of 200 nm and a thickness size of 20 nm.The MH was in line with industry standards.(2)Firstly,the purified magnesium sulfate solution was transformed into vinylated magnesium hydroxide in the presence of silane coupling agent KH570 and ammonia.Then,the styrene(St),methyl methacrylate(MMA)or butyl methacrylate(BA)was used as monomer and the polymer coated MH particles was produced via in-situ copolymerization.The results by FTIR and SEM showed,polymer was grafted on the surface of MH particles via in-situ copolymerization.(3)The modified magnesium hydroxide(MMH)nano-particles and polypropylene(PP)was physically blended to get the PP/MMH composites.The effects of mechanical property,microtopography,melt and crystallization behavior and processability on the PP/MMH composites in different loading level and modified by different monomer.Results of mechanical property indicated that the MMH particles was uniformly dispersed in the PP/MMH composites.The impact section of composites filled by MMH particles present a phenomenon that particles and matrix were peeled and become hollowed.As a result,the materials’ ductile was ductile fracture.Compared with the composites filled by untreated MH particles,the impact strength and tensile strength of the composite were improved.The TGA and DSC results showed that the residues and therm-oxidative stability of PP/MMH composites increased obviously.Especially,when the loading of PMMA-g-MH particles was 20%,the initial degradation temperature was improved 106.8℃.Besides,The MH particles induced higher crystallization temperature and higher crystallization rates and the higher relative crystallinity of the PP composites.The change of MFR make it clear that the loading level has effect on MFR of the composites.At the low loading level,the processability of MMH/PP composite was better than the pure PP material.However,With the increase of loading level,the processability declined gradually.In comparison with the composites filled by untreated MH particles,the MMH particles was dispersed excellently and its interactions with interface of the matrix was stronger.what’s more,the processability of the composite was significantly enhanced.