Hydrophilic fumed silica is a nanomaterials with strong hygroscopicity(absorbing moisture). This fluffy white powder is based on high purity amorphous silica. It is can be wetted by water, and dispersed in water forming a suspension.
When it firstly produced from oxyhydrogen flame，the moisture content is very low. Take XYSIL200 for example, it is around 0.48 wt%. If exposed into air for about 30 seconds to 180 seconds, this number will be double or even tripled.
Hydrophilic fumed silica is mainly used to provide thixotropic properties in coating and adhesive; to provide reinforcement in silicone rubber. Besides, it acts as free flow and absorbing agent in pharmacy, food and cosmetic products.
Various grades can be divided mainly by hydrophilic fumed silica BET surface area. Take XYSIL fumed silica as example, the 200 in XYSIL 200 comes from the value of BET surface area.
Some manufacturer divides into more grades according to applications. The picture below is Aerosil hydrophilic grades, Aerosil A200 F is the grade for food and Aerosil 300 pharma is obviously for pharma.
Due to its strong tendency of absorbing moisture, the hydrophilic fumed silica requires strictly moisture proof. Three layer kraft paper bag and plastic layer around the pallet meet this need. However, this packing is fragile during transporting.
If the original package is open or broken, the product inside should be used as soon as possible.
Some tips on fumed silica provided in this post, along with advice on where/how to…
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