Science project research help- sodium polyacrylate (plant watering beads)

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chrisnickhow
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Science project research help- sodium polyacrylate (plant watering beads)

Post by chrisnickhow »

Science project question is- Do plant watering beads absorb water faster if it is hot or cold.
The plant polymers purchased say to put dry beads in 400 g of distilled water and they will reach full expansion/absorption in 4-6 hours, but that "warm water can be used to speed up this process". Need research sources (scientific books or journals that an elementary school can reasonably understand) to back up the hypothesis that warm water will cause the polymers to absorb more water than cold water in the same amount of time. Please help!
324B21
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Re: Science project research help- sodium polyacrylate (plant watering beads)

Post by 324B21 »

Good Afternoon!!

First, the disclaimer about Sodium Polyacrylate. It is toxic when inhaled or ingested so please take caution. Fortunately, it is mostly an irritant, but it bears worth putting out there for safety sake.

This question is something I have been mulling over, and really haven't found a lot of success online--even in my college online database in finding answers. I have found a few articles that talk about the properties of SP (what I will be using for shorthand in this response). A lot of those articles though are really advanced stuff that go into structure along with information like how we use it for things like fake snow and laundry detergent (as a chelating agent). *Fun fact: NASA uses SP in space suits and space clothing since it can absorb so much liquid. *Second fun fact: Salt is the easiest way to break down SP.

So: The warmer water gets, the more the molecules are agitated, and the more bonds break. This is easy to see when you boil water.

It follows that the warmer the water you use, the more this is agitation is occurring at the time you add the SP (or vice versa..when the warm water is added to the SP). A great example of this are diapers which utilize SP as the absorbing agent for warm urine.

I am putting out the call right now for others to jump in here with more information and perhaps some articles. I will try to have someone else reach out with any pertinent info in this thread! I know I haven't been super helpful here, but I also want to ensure you get a response of some sort acknowledging your inquiry.

I had a lot more success when I keyed out just a tad and looked into polymers and heat in general versus the very specific (but intriguing) question posed here.

Elizabeth
chrisnickhow
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Joined: Fri Nov 20, 2015 1:56 pm
Occupation: Parent

Re: Science project research help- sodium polyacrylate (plant watering beads)

Post by chrisnickhow »

Thank you Elizabeth! I also did the same thing- expanded the research to more generalized information with heat and polymers- however that seemed to generate more information about how warmer temperatures in the environment cause the SP to "shrink" faster, rather than the water temperature used to "expand" the polymers. I emailed my sons teacher to see about changing the question a bit but would still like to hear information from others. Thanks again!
dfcoll
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Re: Science project research help- sodium polyacrylate (plant watering beads)

Post by dfcoll »

Hi chrisnickhow,

Hopefully I can help by adding a little bit to the conversation...

I think it would be useful to look at how the sodium polyacrylate beads are absorbing the water, then determine what effect a higher temperature would have on that process.

I believe the polymer is absorbing water through the process of osmosis - when water molecules move from an area of low solute concentration (pure water), across a permeable barrier, to an area of higher solute concentration (interior of a sodium polyacrylate bead) until equilibrium is reached. Osmosis is described in most basic chemistry texts and science reference books, so hopefully you can find some that are suitable for the elementary level. Increasing the temperature (or kinetic energy) of the water molecules should make the water movement into the beads happen faster.

Some good search terms might be:
osmosis
osmotic pressure
temperature
kinetic energy
polymer gel structure

If you still have trouble finding references, please let us know.

Good luck!
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