Polymer Absorbance: A Swell Project

yash — Sun, 05 Apr 2009 20:57:40 +0000

* Note: This is an abbreviated project idea, without notes to start your background research or a procedure for how to do the experiment. You can identify abbreviated project ideas by the asterisk at the end of the title. If you want a project idea with full instructions, please pick one without an asterisk.

Abstract

Disposable diapers contain a polymer, called sodium acrylate, which is useful for absorbing water. Do background research to learn about sodium acrylate, and how it reacts with water. Make sure that you understand the terms hydrophilic, polarity and hydrogen bonding. Cut out the middle, padded section of a disposable diaper. Cut this into equally-sized square pieces, approximately 10–12 cm on a side. Remove some of the stuffing material so that you can staple the open ends closed. Measure water into a quart jar to fill it half-way. Immerse a diaper pad square in the jar and leave it for at least twenty minutes. Take out the diaper pad square, and allow any dripping water to go back into the jar. Measure how much water is left in the jar, and subtract from the original amount to see how much water the diaper pad square absorbed. Here are some questions you can think about answering with this project. How much water can the diaper pad absorb? Ordinary table salt makes a strongly ionic solution, dissociating into positively-charged sodium ions and negatively-charged chloride ions. What effect will the presence of dissolved salt have on the ability of sodium acrylate to absorb water? How much salt water solution can the diaper pad absorb? (Note: a solution of 10 g salt in 110 ml of water will have about the same concentration of dissolved salt as baby urine.) Sugar makes a non-ionic solution. How much sugar water solution can the diaper pad absorb? How does temperature affect absorption? (Goodstein, 2004, 49–55)

Bibliography

Goodstein, M., 2004. Plastics and Polymers Science Fair Projects: Using Hair Gel, Soda Bottles, and Slimy Stuff. Berkeley Heights, NJ: Enslow Publishers.

Plastic Deformation: Glass Transition of Some Plastics*

yash — Sun, 05 Apr 2009 19:27:48 +0000

Abstract

Some plastics undergo an unusual transition, from a hard, glassy state to a soft, rubbery state, with increased temperature. For this project, you should do background research on the effects of temperature on different types of plastics. Make sure that you understand the difference between thermosetting and thermoplastic polymers. You should also look for information on the glass transition temperature (T_g) for different plastics. Pure polyvinyl acetate has a T_g of 28°C (about 82°F). You can make a sample of this polymer by pouring some Elmer’s Glue-All into a plastic bowl or plate and allowing it to evaporate for several days. Cut strips of the resulting material for your experiments. Try dipping the strip into warm water and immediately wrap it around a pen or pencil to make a spiral. Dip it in ice water. Describe the properties of the polymer at the two temperatures. What happens if the spiral is reheated? Additives in the glue may shift the T_g away from that of pure polyvinyl acetate. Use water heated to different temperatures to determine the T_g for your polymer. Other plastics, such as polystyrene (recycling code #6), have higher T_g’s. With an adult’s help, you can investigate these materials using boiling water. (To raise the temperature of boiling water slightly higher, add a few tablespoons of salt. Search on “colligative properties” to find out how this works.) (Goodstein, 2004, 105–109)

Bibliography

Goodstein, M., 2004. Plastics and Polymers Science Fair Projects: Using Hair Gel, Soda Bottles, and Slimy Stuff. Berkeley Heights, NJ: Enslow Publishers.

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Polymer Absorbance: A Swell Project

Abstract

Bibliography

Plastic Deformation: Glass Transition of Some Plastics*

Abstract

Bibliography