“Extrasorb – Super Absorbent is capable of absorbing water to a level of about 300 times its own weight and its huge water holding and absorbing capacity can be used to retain, block, and absorb liquid and hence turn water to gel. It is capable of absorbing water to a level of about 300 times its own weight and its huge water holding and absorbing capacity can be used to retain, block, and absorb liquid and hence turn water to gel. The ability to absorb depends on the ionic concentration of the aqueous solution and can be as much as 300-500 times the weight of SAP.

Talking in chemical terms, these are the high molecular cross-linked polymers. These cross-linked polymers are the main reason for its highly absorbing nature as these absorb the aqueous solution due to the strong hydrogen bonding with the water molecules. These are made in the presence of an initiator, from the process of polymerization of acrylic acid which is blended with potassium hydroxide or sodium hydroxide to create the respective polyacrylic acid salt.

A diffusion gradient is formed due to the neutralization of the backbone of the polymer by potassium or sodium. Water molecules are attracted to the network because of this diffusion gradient. The cross-linking which exists in the network doesn’t allow the chain to straighten even when it wants to thereby result in the expansion of the particles as the water molecules move through the network.

The water-loving Carboxylic acid group (-CO OH) forms its backbone which makes it hydrophilic. There takes place the interaction of polymer/solvent as and when water is added to the SAP and result in the hydration and formation of hydrogen bonds which is responsible to hold the water tightly.

Super absorbent polymer has basically 2 functional properties which are due to the two modules of elasticity and swelling as discussed below:

It is a very important module for the swollen superabsorbent polymer. The polymer in the powdered form is blended with fibers such as cellulose and thermoplastic. To ensure that very less number of cross-links are there to link the chains together, the polymers chains must have high molecular mass so that it remains hugely insoluble but at the same time highly expandable too.

Osmotic pressure is responsible for the swelling of the cross-linked and ionized network of the polymer. To increase the absorbing capacity there should be as less cross-linking in the polymer as possible to enable the polymer chain to adopt the configuration which is widely spaced.

The degree and the type of cross-linking done to make the gel determine the absorbing and the swelling capacity of the superabsorbent polymer. The density of cross-linking is inversely proportional to the swelling and absorption as explained below:

• If the SAP’s are cross-linked with low density
  then they generally have a tendency to swell to a greater degree and have a more absorbing capacity. It also results in these gels being softer and sticky in nature.Alternatively,
• if the SAP has highly dense cross-linked.
  it results in a low level of absorbing and swelling capacity.