Polymer+Activity-Teacher+notes

A polymer is a very, very long molecule made up of units linked together. These units are called monomers. Each unit in the chain usually has carbon and hydrogen atoms. Many times oxygen atoms are in the chain and on occasion chlorine, fluorine and nitrogen. Biological polymers are classified as polysaccarides (i.e. cellulose and starch), polypeptides (i.e. proteins), and polynucleotides (i.e. DNA, RNA).
 * Polymer Activity **
 * Teacher Notes **
 * What is a polymer? **

The carbon atoms in polymers are held together by covalent bonds. The bonding in a polymer is a large reason for its properties. Simple long chains will allow for more movement between adjacent chains than will chains that have been cross-linked, crystallized or stiffened. The degree of branching in polymer chains also changes its properties (HDPE vs LDPE).

1) cross-linking agents: these make bonds between the polymer chains 2) Inorganic fillers: Stiffeners – these will stiffen the polymer by filling in the spaces between chains preventing the carbon chains from rotating. These “fillers” are large molecules added to the chain (steric hinderance)
 * __ In this lab there will be two ways to strengthen the polymer: __**

1) reactants used 2) stretch ability (pull it and see how far it will stretch before breaking) 3) rigidity or stiffness (try putting sudden stress on it to see if it will break or bend) 4) bounce (try bouncing it on the counter or table) 5) viscosity (resistance to flow: how easily does it “ooze” and flatten on its own?) 6) texture (smooth, rough)
 * __ Data should be collected in the following areas: __**

5 paper cups 4 wooden craft sticks (for stirring the mixture) 4 plastic sandwich bags (for kneading the mixture) White glue Liquid laundry starch (Purex Sta-Flo) Powdered calcium carbonate (chalk) Calcium sulfate (Plaster of Paris) 4% sodium tetraborate decahydrate solution (borax)
 * Equipment/supplies per group: **

25 mL of white glue 25 mL of liquid laundry starch
 * 4 different mixtures are as follows: **
 * __Polymer mixture A__**: (this mixture contains a cross-linking agent but no filler)

Put both glue and starch together in a paper cup and mix for at least 5-6 minutes. Test product.

30 mL of white glue 20 mL of liquid laundry starch 10 g of powdered calcium carbonate, chalk
 * __Polymer mixture B:__** (this mixture contains a cross-linking agent and an inorganic filler)

Put the chalk on the bottom of a paper cup. Add the liquid laundry starch and stir until the chalk is completely dispersed. Stirring constantly, add the glue. After several minutes, transfer the mixture to a sandwich bag and knead for at least 5-6 minutes. Test your product.

30 mL of white glue 20 mL of liquid laundry starch 5 g of powdered calcium carbonate, chalk 20 g of calcium sulfate, Plaster of Paris
 * __Polymer mixture C:__** (this mixture contains a cross –linking agent and two inorganic fillers!)

Put the chalk and the Plaster of Paris on the bottom of a paper cup. Add the liquid laundry starch and stir until both fillers are completely dispersed. Stirring constantly, add the glue. After several minutes, transfer the mixture to a sandwich bag and knead for at least 5-6 minutes. Test your product.


 * __Polymer mixture D:__** (this mixture the amount of cross-linking is increased by using a higher concentration of that ion (borate ion). There is also a filler, in this experiment it will be talc which is a silicate mineral)

30 mL of white glue 20 mL of water 5 g of talc 6 mL of 4% borax

Completely mix 25 mL of glue with 20 mL of water in a paper cup. Place talc into a second cup. Slowly add the diluted glue to the talc powder in the second cup. Stir for several minutes. Stirring constantly, add the 4% borax very slowly and gradually. After several minutes, transfer the mixture to a sandwich bag and knead for about 5-6 minutes. Test your product.

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thanks and enjoy, AnnMarie