without real or apparent crystalline form.
Glossary
A
Amorphous
Anti-caking
function of prevention of formation lumps or caking in powders.
Anti-settling
function of prevention of settling of pigments or fillers in liquid systems.
B
Bulk density
bulk density is a measure of weight of fumed silica per unit volume (g/L).
C
Carrier
function of carrying other active ingredients.
D
Densed
description of fumed silica with density that is approximately 2 times the standard density.
Dielectric properties
description of material properties usually associated with its performanceas an insulator.
F
Flexography
a system of printing on a rotary press employing water-based ink, used especially for printing on plastic, paper, or cardboard.
Flowability
is thought as a onedimentional characteristic of the material, whereby powders can be ranked on sliding scale from free-flowing to nonflowing.
Fumed silica
special amorphous form of silica produced by method of vapor phase hydrolysis that results in pure, x-ray amorphous, silicon dioxide.
H
Hydrolysis
chemical process in which a molecule is cleaved into two parts by the addition of a molecule of water.
Hydrophilic
a hydrophilic fumed silica is one that exhibits an affinity to water.
Hydrophobic
a hydrophobic fumed silica is one that does not exhibit affinity to water.
M
Morphology
shape and structure of particles and aggregate of particles.
P
Pyrogenic
produced under conditions involving intense heat.
R
Rheology
characteristics of the materials during deformation and flow.
Rigidity
the physical property of being stiff and bending resistant.
S
Sieve residue
larger agglomerate formations of fumed silica given as % of total weight.
Silicon dioxide
a white or colorless vitreous insoluble solid (SiO2); various forms occur widely in the earth's crust as quartz or cristobalite as well as in amorphous form.
Silicon tetrachloride
(SiCl4) is a colourless volatile liquid. It's most commonly prepared by reacting chlorine with hot silicon: Si + 2 Cl2 →SiCl4
Surface area
total specific area of aggregate and agglomerate surfaces of fumed silica structure (measured by BET method).
Suspension
state of a substance when its particles are mixed but not dissolved in a fluid or solid.
T
Thixotropy
reversible behaviour in a system that exhibits decrease in viscosity when shear force is applied. System regains viscosity in time-dependent way as shear force application stops.
U
Undensed
description of fumed silica with standard density.
V
Viscosity
resistance of a liquid to sheer forces and hence to flow.