Synthesis And Application Of Magnesium Hydroxide Composite Materials Modified By Organic Silicon Resin

In the process of application of polymer materials,it has a long history to add inorganic filler to the polymer matrix for reducing the cost and improving the performance of composite material. With the development of the research on inorganic nanoparticles,it is shown that polymeric nanocomposites consisting of inorganic nanoparticles and organic polymers exhibit improved performance compared to their microparticle counterparts.However, Whatever the filler is nanoparticles or microparticles to the polymeric composite, the main problem is the prevention of particle aggregation and the compatibility. This problem can be overcome by modification of the surface of the inorganic particles.Our research focus on the modification of micron magnesium hydroxide which commonly used in industry. We use a series of acrylic resin which modified by organic silicone as modifying agent to magnesium hydroxide. Our research is composed of the following three aspects:First of all, in order to explore the feasibility of the modifing magnesium hydroxide by resin.We use methacryloxy propyl trimethoxyl silane (KH—570) and acrylic monomers copolymerization into silicon acrylic resin.Then the resin under the condition of isopropyl alcohol to modified magnesium hydroxide.The results showed that the silicone modified acrylic resin success to the surface of magnesium hydroxide, and the modification efficiency is as high as 20%.After modification, the average particle size of magnesium hydroxide particles from 3 micron reduce to 1 micron with a better dispersion and narrower particle size distribution.We proved that the combination power of hydroxyl silicon and magnesium hydroxide is greater than the carboxyl.The more silicon hydroxyl on the resin chain segment, the more aggregation magnesium hydroxide made.The tensile strength of modified magnesium hydroxide composite combined with low density polyethylene enhanced to the unmodified one. When content of KH— 570 in silicone/acrylic resin is 20%, the mechanical properties of composite is optimum as the tensile strength of 8.80 MPa.For reasons of environmental protection and the feasibility of industrialization, we use water instead of isopropyl alcohol solvent. We synthesize silicon acrylic resin with long alkyl side chain to modify magnesium hydroxide.Under the condition of water-borne modification is successful.Such modification also made the size of magnesium hydroxide smaller.The sedimentation time of magnesium hydroxide modified by long alkyl side chain of silicon acrylic resin was longest in acetone.The mechanical properties of composite material increased with the increase of adding amount of acrylic resin.Resin content is 20%, the best material mechanics performance.In order to avoid the aggregation of magnesium hydroxide, we made silicon acrylic resin and diethoxydimethylsilane into emulsion, then modified magnesium hydroxide. When the emulsion addition amount is only 5%, the average particle size of magnesium hydroxide particle is extended to 360nm.The modified magnesium hydroxide particle presents a lamella hexagon structure.The thermal stability and mechanical properties of the composite material is the best. When emulsion adding amount was 5%, the thermal stability and mechanical performance is the best, as the tensile strength of 10.10 MPa.Close to the tensile strength of the pure low density polyethylene.