• To become more familiar with polymers and their uses.
• To prepare four polymer elastomers in the laboratory
• To compare physical properties of the four elastomers prepared in the laboratory.

Applicable Science Concepts:

• Definition of a polymer
• Definition of an elastomer
• Definition of crosslinking
• National Standards for 5-8
• National Standards for 9-12

Materials:

• Elmer's® White Glue-All
    (30 mL per ball)
• Elmer's® Blue Glue Gel
    (30 mL per ball)
• Borax powder, Na₂B₄O₇•10H₂O
    (1 g per ball)
• Liquid latex rubber, from local craft or hobby store
    (15 mL per ball)
• 5% acetic acid solution, CH₃COOH(aq), (household vinegar)
    (15 mL per ball)
• Saturated sodium silicate solution, Na₂SiO₃(aq)
    (12 mL per ball)
• 50% ethanol solution, C₂H₅OH(aq)
    (3 mL per ball)
• Small disposable plastic cups
• Plastic stirring rod or wooden stick
• Tap water
• Small sealable plastic bags
• Paper Towels

Equipment:

• Balance
• Weighing boats or weighing paper
• Meterstick and/or metric ruler
• Small length of string
• Graduated cylinder

Safety:

• Safety goggles and lab aprons should be worn to protect eyes and clothing.  This is especially important when working with the latex and sodium silicate polymer experiments.
• If a chemical gets into eyes, immediately flush eyes with water.
• Elmer's® White Glue-All and Blue Glue Gel are nontoxic, but should not be ingested.
• Borax is sodium tetraborate decahydrate, Na₂B₄O₇ •10H₂O.  It is an eye irritant.
• Liquid Latex is preserved in ammonia and has a very strong odor.  Do not inhale.  It may also irritate skin, so handle with gloves.  If it comes in contact with skin, wash thoroughly with soap and water.
• 5% acetic acid solution, HC₂H₃O₂(aq), is the same as household vinegar.
• Sodium silicate solution is irritating to skin.  Handle with gloves.
• Ethanol is flammable.  Keep away from flames.
• For Material Safety Data Sheets (MSDS) on these chemicals, click here.

Experiment:

• Preparation:  Construct polymer balls according to procedures in the table below.

Polymer Balls
Ball #1 Elmer's® White Glue-All and Borax Powder	Ball #2 Elmer's® Blue Glue Gel and Borax Solution	Ball #3 Liquid Latex and Acetic Acid Solution	Ball #4 Sodium Silicate Solution and Ethanol Solution
Procedure for Ball #1	Procedure for Ball #2	Procedure for Ball #3	Procedure for Ball #4

• Investigations:  Conduct the following tests on polymer balls.


Physical Appearance:  Describe the texture, color, and other observable characteristics.
Volume:  Determine volume without using water displacement method.  (Water will break down some of the polymers.)
Density:  Find the density of each polymer ball.
Bounce Height:  Drop each ball from the same height and record how high it bounces.  Repeat the procedure until you have consistent data.
Temperature Changes: Describe the changes in properties after the polymer balls have been heated and cooled.
Day 2 Observations:  Leave balls out at least 24 hours.  Repeat all tests.  Compare data from previous trials.  (Additional experiment:  Create two sets of balls.  Seal one set in plastic bags and leave the other set out.  Compare the data from the two sets of balls as well as the data from original tests.)
• Photo Documentation:  Click here for photographs from this experiment.