Microwave-assisted Surface Modification Of Wollastonite Powder

Wollastonite is a kind of new industrial mineral. Comparing with other mineral, wollastonite shows lots of advantages, such as innocuous, resistance to chemical attack, low oil absorbency, low price and needle-like shape. It is widely used for frictional material industrial. The consistency between inorganic filler and polymer material is not good and the dispersion of inorganic filler in polymer material is very bad. So we need to modify the surface of wollastonite powder to increase the consistency and the dispersion of wollastonite powder in inorganicmaterial.The methods of powder surface modification in existence including wet modification and the dry modification processing. Assistant measures are needed especially in chemistry modification, such as heating and churning up the powder and modifier. The heating methods now are all the transmission"from outside to inside",also the heating rate cannot be too fast to avoid big temperature grads, and it cannot heat selectively. Therefore, it is a quest and a breakthrough task to research and exploit new surface modification methods of powder.Microwave has microwave chemistry with its"thermal effect"and"non-thermal effect"characteristics. Microwave is widely used in chemistry, analytical chemistry, ceramic sintering, rubber, plastic etc. It is a quite actively new embranchment subject.The paper has researched the physical chemistry mechanism between wollastonit powder and silane coupling agent at the point of wet surface modification and microwave chemistry, and supposed to provide modification technology and microwave chemistry, the theory and experiment warrant for microwave-assisted wet modification of wollastonit powder, and discussed themechanism.Specific work and the results are as follows:Wet Surface modification of wollastonite powder withγ-Aminopropyl triethoxy silane (KH-550) by microwave-assisted heating was studied in the present work. It was shown by FT-IR,XRD,and SEM that the wollastonite was modified by silane coupling agents (KH-550) compounded with the Si—OH of wollastonite powder. During the course of microwave heating assisted Surface modification of wollastonite powder, The Crystal Structure of wollastonite and the Molecular Structure of ultra-fine sericite with silane coupling agents neither change. Characterization of grafting ratio use Weighing-extraction method. The effects of mass fraction of silane coupling agents; coupling temperature; coupling time; drying time and drying temperature; on the surface modification of wollastonite powder were investigated. The optimum microwave-assisted heating coupling reaction conditions: mass fraction of silane coupling agents 9%; coupling temperature 80℃; coupling time 30min; drying time 30min and drying temperature 115℃.The optimum Water-bath heating assisted reaction conditions: mass fraction of silane coupling agents 10%; coupling temperature 80℃; coupling time 60min; drying time 60min and drying temperature 115℃(Other reaction conditions being the same). The results showed that of microwave-assisted heating coupling reaction is substantial increase in Chemical grafting ratio and Thermal efficiency.