![]() It is, however, irritating to the eye and nasal membranes. Water is no longer needed inside the polymer to balance the salt concentration, so the structure collapses or deflates. An extension of this experiment involves taking a baby diaper apart to determine which part of the diaper "keeps baby dry".Īddition of salts of sodium or calcium reverses the swelling process. It can absorb about 30 times its own weight in urine. Sodium polyacrylate is the main ingredient in baby diapers used to "keep baby dry". PolySnow™ gets its name from the fact that, within a certain concentration range, it absorbs water to form not the usual gel, but white particles that resemble snowflakes. Sodium polyacrylate has fewer cross-links, and therefore can absorb more water than the PolySnow™. Sodium polyacrylate and PolySnow™ differ in the amount of cross-linking. The amount of cross-linking, called the crosslink density, determines the properties of the super absorber. Sodium polyacrylate and PolySnow™ are both forms of the same material and are both examples of super-absorbing polymers. How many times its own weight in water did the polymer absorb? Answer: 120g/0.35g=342.86 or approximately 343 times its weight! In the case of the sodium polyacrylate, 1/8 teaspoon of the powdered polymer weighs 0.35 grams 4 oz. Did the addition of salt have the same effect on the PolySnow™ as with the sodium polyacrylate?.Add a teaspoon of table salt (NaCl) or calcium chloride to both the swollen polymers.Does PolySnow™ absorb as much water as the sodium polyacrylate?.How does PolySnow™ differ in appearance from the sodium polyacrylate?.Gently touch the polymers in the cups.Continue adding water to both cups until absorption seems to stop. squeeze bottle, slowly add distilled water to each of the powders, stirring gently letting each powder absorb the water before adding more.Ĥ. Place 1/4 teaspoon of PolySnow™ in another cup.ģ. Place 1/8 teaspoon of sodium polyacrylate powder in a plastic cupĢ. Squeeze bottles or containers of known volumeġ.PolySnow™ powder (available from Flinn Scientific Inc.).Sodium Polyacrylate powder (available from Flinn Scientific Inc.).The experiment below will illustrate this phenomenon. Sodium polyacrylate can absorb 800 times its weight in distilled water, but only 300 times its weight in tap water, since tap water contains some sodium, calcium and other mineral salts. The cross-links that connect the chains together prevent them from dissolving/breaking apart in the water. Water swells the polymer network to try to keep the sodium concentration balanced between the polymer and the water. When these sodium atoms leave, they are replaced with water molecules. That means, some of the sodium atoms want to leave the network and move to the water. When the (sodium-containing) polymer is placed in contact with water, there is a tendency for the sodium to distribute equally between the network and the water. It absorbs water by a process called osmosis. It is a cross-linked (network) polymer that contains sodium atoms. Sodium polyacrylate is an example of a super-absorbing polymer.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |