Organically Modified Silica Prepared By Mechanochemical And The Study Of Its Composite Materials

Organic-inorganic composite materials which have the advantages of organicand inorganic materials, with an excellent performance, are widely used. Inorganicparticles which are added in the organic polymer matrix to prepare organic-inorganiccomposite materials with two-phase uniformly dispersed have been a hot. Issues ofinorganic particles uniformly dispersed in the polymer matrix and the two-phaseinterfacial bond restrict the development of organic-inorganic composite materials.In this paper, method of mechanochemical was employed to modify silica’ssurface, the reactive monomer, two kinds of styrene and methyl methacrylate, wasselected as modifying agents. The structure and properties of modified silica powderwas characterized by particle size analysis, infrared spectroscopy, activity index,thermal gravimetric analysis, surface wettability analysis, transmission electronmicroscopy analysis, and so on. The structure and properties of silica before and aftermodification, and the modifying effect of two modifiers were compared each other.Two kinds of silica, modified and unmodified silica, were added to unsaturatedpolyester resin, the composite material were analyzed by sedimentation, waterabsorption, flexural strength, the scanning section, the performance of the thermalanalysis.After a high-energy ball milling modified by styrene and methyl methacrylate,the average median particle size of styrene-modified inorganic particles1.849μm,methyl methacrylate-modified silica is1.767μm, with wide particle size distribution;the activity index of styrene modified silica particles can be up to93.5%, while themethyl methacrylate-modified silica’s activity index is only60.5%; the modifiedpowder slurry have a sedimentation stability and the deposition is flocculent, noagglomerate, yet methyl methacrylate-modified powders are combined into densesediment binding lumps; the surface contact angle of Styrene-modified powder can beup to128.8°, which have excellent surface hydrophobicity, the contact angle ofmethyl methacrylate-modified silica is only41.7°, with a certain hydrophilic,unmodified of the powder material is extremely hydrophilic; After ball millingmodification, shape of the particle is irregular, the size is uniform, and the surface of styrene-modified powders have the transparent organic coating layer; IR analysisindicates that there is the presence of chemical bond between the inorganic particlesand organic surfaces; thermal analysis showed that the grafting rate of styrenemodified particles is about4.39percent, but the grafting rate of methyl methacrylatepowder is only1.8%; the influence of process conditions on the modification effectwas analysis by orthogonal experiments, the result showed that the ball ratio have themost important influence on the effect of modification, which followed by is millingtime, the effect of ball milling speed is min.From the analysis of the prepared composites, we know that: the silica aftermodification/unsaturated polyester composite slurry has excellent sedimentationstability, with low absorption rate, the bending strength of the composite which wasadded unmodified silica decreased4.89MPa, then addition of modified silica canmake the bending strength of the composite material increase by about5~9MPa, andthe silica uniformly disperse in a resin matrix, with good compatibility, the thermalstability of the composites were improved, at the same weight loss rate, the modifiedsilica composite’s heat resistant temperature can be increased by5~10℃.Inorganic particles which have good compatibility with the organic polymer canbe prepared by mechanical, during the high-energy ball milling, surface of inorganicparticles can achieve the change from hydrophilic to hydrophobic, the compatibilityof the inorganic and organic polymer is significantly improved, organic-inorganiccomposite material with excellent performance can be prepared.