Gel
From Wikipedia, the free encyclopedia
- In optical filters and theatrical lighting a color gel is a transparent or translucent colored panel used to change the color of transmitted light.
A gel (from the lat. gelu—freezing, cold, ice or gelatus—frozen, immobile) is a colloidal system in which a porous network of interconnected nanoparticles spans the volume of a liquid medium. In general, gels are apparently solid, jelly-like materials. Both by weight and volume, gels are mostly liquid in composition and thus exhibit densities similar to liquids, however have the structural coherence of a solid. An example of a common gel is edible gelatin.
Many gels display thixotropy - they become fluid when agitated, but resolidify when resting.
By replacing the liquid with gas it is possible to prepare aerogels, materials with exceptional properties including very low density, high specific surface areas, and excellent thermal insulation properties.
In 2005 a sound induced gelation effect was demonstrated.
[edit] Applications
Many substances can form gels when a suitable or is added to their formula. This approach is common in manufacture of wide range of products, from foods to paints, adhesives.
In fiber optics communications, a gel resembling in viscosity is used to surround a fiber, or multiple fibers, enclosed in a loose tube. This gel serves to lubricate and support the fibers in the buffer tube. It also prevents water intrusion if the buffer tube is breached.
Gels are an important part of chemistry, and can be used to form solids.
The classification of gels and jellies: Gels can be loosely classified along the following lines:
1 - Either inorganic or organic in nature
2 - Having water (hydrogels), or an organic solvent (organogels) as the liquid component
3 - Being either colloidal or coarse in nature (size of the particles which form the framework)
4 - As a rigid gels, elastic jellies, and gels
