- Physical State: Powder
- Usage: Industrial
Super absorbents are synthetic polymers with water retention properties for a variety of uses. WATERLOCK is supplied as white powder. In contact with water the polymer hydrates and becomes a transparent gel. Each particle however remains separate and can absorb up to 500 times its weight of water resulting in a five hundred fold increase in particle size. Unlike most substances, which hydrate, the hydration are fully reversible and the particle can return to its original size. The water can be removed by a variety of methods such as heating or high pressure. The polymer can thus act as water reservoir, that can be filled and emptied many times. WATERLOCK
will absorb upto 800 times its own weight of distilled water. In water containing salts and minerals the absorption potential will vary. WATERLOCK
is crosslinked polyacrylamide copolymer, that absorbs water. Its action can be compared to a sponge except that while a sponge retains its size with or without water, WATERLOCK
swells and shrinks as it hydrates and dehydrates. It thus functions as a water reservoir. The absorption capacity is variable depending on the quality of the water.
|Distilled water||About 800 times its weight.|
|Water with 1000 ppm of NaCl||About 400 times its weight.|
The pH of the water will have little effect on the absorption potential within the range of 5 to 10. It must be remembered that the pH is not a measure of the salt concentration and a neutral pH does not necessarily mean that the water is not high in salts. In an eight per cent calcium chloride solution swelling is reduced by a factor of ten. In the presence of high levels of iron and aluminium an external skin can be formed on the polymer, which greatly reduces the water retention capacity.
WATERLOCK is virtually unaffected by short exposure to boiling water. After prolonged exposure a certain amount of hydrolysis of the polymer may occur, especially at high pH. This hydrolysis will have a limited effect on the water absorbing capacity of the polymer. Water held by the polymer is fixed and not sensitive to removal by pressure or centrifugal forces until above 5 bars is exerted.
The stability of the polymer to bacterial degradation is variable depending on number of factors. In aerobic condition little degradation is observed and the polymer may be expected to function well for at least five years. In anaerobic conditions the polymer can be broken down by the ferrous ions created by the action of sulphate reducing bacteria.Mechanism
To understand how this polymer functions to absorb water, we can consider a simplified model of a single molecule. Each molecule can be represented by parallel rows of the principal atoms with periodical bridging links between them. When water comes into contact with these rows an electrical repulsion between rows is generated, rather as in the poles of magnet, and the rows move apart. This draws more water into the molecule and the rows move further apart. This results in a rapid swelling of each particle. The water can be removed from the polymer either by evaporation or by exerting pressure beyond 5 bars. The molecule on losing water contracts to its original size. This swell and shrink cycle can be repeated indefinitely.Technical DataSodium polyacrylate
|FORM - dry||Crystalline white powder / granules|
|FORM - wet||Transparent gel|