The fast emerging SAPs

Diapers, nappies…..applications of superabsorbent polymers (SAPs) are spreading fast and the scope is endless, which has opened a new avenue for researchers and manufacturers to develop better understanding of processing of fibres in order to achieve unique properties to specific end uses, say Prof SK Laga and Joshi Rashmi.

The world is now witnessing the dawn of polymer science and biotechnology. Due to technological advances and innovations, polymers are gate-crashing into any field of applications right from human life to high technology era. Intensive research works are being carried out to make tailor-made superabsorbent polymers. Medical textiles are major growth areas of technical textiles industry, in which superabsorbent polymers occupy an important place.

SAPs have caused a huge revolution in the personal health. This article deals with the manufacturing of superabsorbents with a focus on their potential properties. Superabsorbent polymers (SAPs) are materials that have the ability to absorb and retain large volumes of water and aqueous solutions. This makes them ideal for use in water absorbing applications such as baby nappies and adult incontinence pads to absorbent medical dressings and controlled release medium.

Early superabsorbents were made from chemically modified starch and cellulose and other polymers like poly (vinyl alcohol) PVA, poly (ethylene oxide) PEO all of which are hydrophilic and have a high affinity for water. When lightly cross-linked, chemically or physically, these polymers become water-swellable but not water soluble. Todays superabsorbent polymers are made from partially neutralised, lightly cross-linked poly (acrylic acid), which has been proven to give the best performance versus cost ratio.

The super-absorbent material has many applications; for example, it is used in the disposable diapers that can absorb a large amount of water, which helps the baby stay dry for more time. The chemical used in the diapers is mostly sodium polyacrylamide with potassium salt base, it is a safe, non-toxic polymer and can hold over 200 times its weight in water, release it slowly over time in horticultural applications. In the industry, superabsorbent polymers can be used in oil drilling and reducing soil erosion[1].

What are superabsorbents?

Superabsorbent polymers (SAPs) are hydrogels that absorb water at hundred times their own volume. Normally, a superabsorbent gel is a slightly cross-linked polymer network in which the polymer chain are often poly-electrolytes and contain carboxylate electrolytes and contain carboxylate anions and sodium cation. The concentration of ionic group inside the gel network results in an osmotic pressure difference. This is a driving force behind its superabsorbency.

The term superabsorbent polymer particle is intended to include any particulate form of superabsorbent polymer, including irregular granules, spherical particles (beads), powder, flakes, staple fibres and other elongated particle, which can absorb large amount of water compared with general water absorbing materials in which is hardly removable even under some pressure.

A superabsorbent is a water soluble compound which has been cross-linked to render it water insoluble but still swellable to at least 15 times its own weight in physiological saline solution. Thus superabsorbents are cross-linked network of hydrophilic polymers with a high capacity for water uptake[2].

Superabsorbent polymers (SAPs) are hydrogels that absorb water at hundred times their own volume. Normally, a superabsorbent gel is a slightly cross-linked polymer network in which the polymer chain are often poly-electrolytes and contain carboxylate electrolytes and contain carboxylate anions a