Super Absorbent Polymer.
Updated: Feb 9, 2021
Super Absorbent Polymer? What is that? Sounds Super!
Also known as SAP, super absorbent polymers have great affinity for water. Discovered in the late 1930s to early 40s, this magical molecular structure has properly been applied to so many products and has proven to be life changing. What is SAP, where did it come from, what is it used for? Together we will tap the surface of this incredible science project that ended in great success and innovation.
For starters, water absorbing materials in the 20s only held 11x their weight and most of the absorbed contents were lost under moderate pressure. Today SAPs hold up to 300x their weight. When combined with liquid, a chemical bond turns SAPs into a gel that never turns back into liquid! Decades of science led us to sodium polyacrylate, in which the absorption mechanism is caused by osmosis. This feature allows SAPs to be the backbone of various applications such as, personal care products, agriculture, electrical cables and construction.
In scientific terms:
SAP is sodium polyacrylate, sodium salt of polyacrylic acidwith the chemical formula [−CH2−CH(CO2Na)−]n. Sodium gives it the ability to absorb liquid. When water dissolves, it creates a thick and transparent solution (hydrogel) due to the ionic interactions of the molecules. The osmotic pressure causes the sodium polyacrylate to absorb water to balance the concentration of sodium ions inside and outside the polymer.
SAP is a powder-like polymer that immediately absorbs the liquid it comes in contact with. A chemical reaction takes place and the SAPs immediately form into a gel. This gel substance maintains integrity, never dividing back into liquid and powder.
SAP was introduced to diapers in the 80’s. Researchers at Oregon State University noticed from 94’-04’ that more and more babies and toddlers were prolonging the potty-training process. Their discussions after their experiments led them to believe why kids want to stay in diapers longer. However, the SAP makes it a pleasant experience.
· After urination they’re immediately dry!
· Diaper can hold up to 10 pees!
· Their clothes stay dry!
· When they pee, the gel pad that’s formed adds a cushion for their falls!
From diapers to spacesuits, sodium polyacrylate assists in the safety and comfort for the user. Since sodium polyacrylate can absorb and retain water molecules, it is considered a thickening agent because it increases the viscosity of water-based compounds. In diapers, sodium polyacrylate absorbs water found in urine in order to increase the capacity to store liquid and to reduce rashes. In spacesuits, sodium polyacrylate prevent rashes from developing during flight by absorbing various liquids. NASA’s Maximum Absorbency Garment (MAG) absorbs liquid from urine and feces and can hold approximately 2L of liquid. If NASA uses it, you know it is top notch!
We might be bias, but the greatest use of SAP is found in Nateen’s disposable personal care products; baby diapers, adult diapers, under pads and sanitary napkins. We hope you’ve enjoyed this window into the innovation that helps manufacturers around the world improve the lives of their users every day.