Why is polymer gel used in nappies

The layer below the top-sheet is the acquisition layer. Cotton absorbs up to 27 times its weight in water. Salts and other compounds in urine reduce the amount that it absorbs relative to this figure, but it still does a pretty good job of soaking it up.

The absorbent layer underneath the acquisition layer contains some cotton too but also contains another polymer: sodium polyacrylate. This is a superabsorbent polymer which is able to absorb a whopping times its own weight in distilled water. As with cotton, the amount of urine it can absorb is reduced by other compounds found within urine.

Even so, it still manages a pretty impressive 30 times its own weight. As it absorbs the urine, it forms a gel, preventing wetness inside the nappy. The average six-month-old produces approximately 15 grams of urine per hour. The final disposable nappy layer is the water-resistant back-sheet. This is commonly in the form of a coloured line, which changes colour when the interior of the nappy is wet, letting parents know when the nappy needs to be changed. If tubs are in short supply, large zip-lock bags can be used.

Students put the nappy in the bag, zip it up and manipulate it until all the hydrogel is extracted and then proceed as per the directions. Procedure Hair gel Put a blob of hair gel onto the petri dish lid. A large teaspoonful is fine. Gently sprinkle salt from a spatula over the hair gel. Disposable nappies Cut the middle section out of the nappy — the thicker piece that is designed to absorb the urine.

Discard the other piece. Make sure the ice cream container is completely dry - wipe it with a paper towel if necessary. Any moisture in the tub stops the experiment from working properly. Wear eye protection for the next step. Put the centre piece of the nappy into the ice cream container and gently take it apart.

Small white grains should start coming away and this is what you are trying to collect. Keep gently pulling the nappy apart until you have collected as many of the grains as you can. Do not do this roughly or you will lose your product and put a lot of dust and fluff into the air.

Avoid breathing in any of the dust. Remove and dispose of all the fluff and other parts of the nappy, keeping the grains in the bottom of the tub. They are heavier and fall to the bottom, which makes it easier to separate them out. Estimate the volume of the grains. Pour them into the large beaker and add about cm 3 of distilled water. Keep adding distilled water until no more can be absorbed and stir between each addition.

Estimate the final volume of the hydrogel. Add a dessertspoonful of salt and stir. Teaching notes This activity can be used to enhance the teaching of ionic and covalent bonding, or hydrogels can be considered as an interesting polymer as well as an example of a smart material.

Show Fullscreen Source: Royal Society of Chemistry The polymer chain of a hydrogel, from which hydrogen atoms are removed in water to leave negative charges along the length of the structure.

Download all. Additional information This is a resource from the Practical Chemistry project , developed by the Nuffield Foundation and the Royal Society of Chemistry. Level years years years. Use Practical experiments Handout Download. Category Structure and bonding Materials Applications of chemistry Polymers. Related articles. Feature Brilliant buffers TZ Use this infographic with your 16—18 students to develop their understanding of pH and buffers.

News Cooling homes with an endothermic reaction TZ Looking at the use of ammonium nitrate in a new and renewable cooling process. Sodium Polyacrylate Diaper Polymer 24 reviews. Read Reviews Write a Review.

Description This is the super-absorbent polymer found in disposable baby diapers. Also used in many "disappearing water" magic tricks, this fine white powder instantly turns liquid water into a slush-like solid substance.

Technically speaking, the polymer absorbs from to 1, times its own weight in water. Simply add table salt to reverse the reaction. Safe and amazing -- your students will love it! Download the SDS of this product. Video Your browser does not support the video tag. Lesson Ideas Download the pdf of this lesson!

Write a Review Reviews 24 reviews. Mar 14, This works better than powder I've purchased elsewhere. Super fast acting and absolutely absorbs more than what I had. Shipping was fast too. May 14, From reading the reviews, it appears that everyone is happy with the product one did not like the cost and have used it in a number of ways. At outreach events that are "stage show" type of presentations, we use it as the disappearing water cup trick.

We have three cups, one with the sodium polyacrylate in it. We add water to that cup and them tell the audience that we are going to shuffle the cups and they are to keep their eyes on the one with water.

Of course, when we show that all the cups are "empty" we add more water to that cup and shuffle them again. We repeat one more time and then by shaking hard, we empty the "empty" cup into a glass dish so all can see. Many have seen this trick but we do it anyway. We do talk about what's happening and its use in diapers. If time allows, we even remove some from a diaper and show how it to absorbs water. Finally, we show the effect of adding salt to the mixture releases the water, salt being more attractive than the water.

For higher grades and adults we are also able to explain the chemistry and uses other than just diapers. Good product that goes along nicely with the Instant Snow Polymer. Apr 30, This chemical was required for the lab portion of the U. Chemistry Olympiad National Exam. Our stockroom did not have it so I ordered it from Educational Innovations. The order arrived in two days and was exactly what we needed.

Mar 11, Through investigations, they discover how matter is used to keep babies dry. Great for reinforcing NGSS matter concepts in 2nd and 5th grade. Feb 16, I have used this product in a number of ways. The way that the kids seemed to like the bast was when we used it to predict the amount of water that one gram of the stuff would hold before puddling.

Was a great intro to science methodology. Feb 11, Apr 6, I use this at the beginning of the year for the scientific method. It really gets kids thinking. I also use it in an inquiry lab where they have to modify hand warmers to make them hotter. There are tons of ways to use it. Highly recommended. Nov 3, Aug 12, Fun product to use while learning about the scientific method. Look up lesson ideas online. Feb 24, Dec 4, Aug 28, What a great way for kids excited about science at the beginning of the year!

So easy to use! Jul 27, Apr 22, What an amazing product for children. I used this to visualize the scripture Hebrews