Pretreatment techniques milling

Clearly, the availability of the four-stepwise hierarchy in the structure of the nanosilica powder could cause some dependencies of the structural features and other characteristics of the colloidal dispersions on the pretreatment techniques and other conditions, which can influence the particles differently from different hierarchic levels. Therefore, several types of the sample preparation technique were applied. There were (a) ultrasonic (US) treatment of the freshly prepared suspensions of nanosilica (at different concentrations) at =1-12 h (Figures 1.89,1.90, and 1.95) (b) pretreatment of a dry silica powder in the ball mill for t cA = 1-24 h, then preparation of the aqueous suspensions sonicated for 1-9 h (c) MCA of the aqueous suspensions of silica in the ball mill for 0.1-24 h (d) MCA of the mixtures of the aqueous suspensions of silica and other compounds for 5-7 h and (e) addition of some compounds (polymers, biomacromolecules, surfactants, drugs) to the ball-milled suspensions of silica (vide infra). 

The undiluted silane is added directly to the polymer before or together with the filler. It is essential that the resin does not prematurely react with the silane as otherwise the coupling efficiency will be reduced. Typical compounding equipment consists of internal mixers, kneaders, Banbury mixers, two-roll mills, or extruders. The integral blend technique is widely used in resin/filler systems because of its great simplicity and possible cost advantages. This is mainly due to the one-step process and the lower raw material costs (untreated mineral plus silane compared to pretreated mineral) despite the fact that more silane is needed to achieve comparable performance in the finished composite. 

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