Cross Linking Polymers：交联聚合物

Cross Linking Polymers：交联聚合物 Name ______________________ Date ____________ Inquiry Activity 5 – Synthesizing A Polymer Background: A polymer is a large molecule composed of repeating structural units. These sub-units are usually connected by covalent chemical bonds (sharing electrons). Polymerization is the process of combining smaller molecules (monomers) into longer chains or networks. In this activity you will create a cross-linked polymer from Elmer’s Glue and Borax. Elmer’s glue is also known as polyvinyl acetate (PVA) It is an organic compound with the chemical formula (CHO). Borax is a common 462n household cleaning agent. It is also known as sodium borate, a boron compound with chemical formula NaBO?10HO. 2472 Adding Elmer’s Glue to a water/borax solution causes a chemical reaction between the glue molecules and the borax molecules to produce a highly flexible, cross-linked polymer. This polymer is similar to silly putty (real silly putty will not dry out like this material). Instructions: Gather the materials at your lab table. These include: , Borax and water solution in plastic bowl , Elmer’s glue (about 8 ounces) , Paper Towels , Food Coloring , Zip Lock Bag 1. Add 1-2 drops of food coloring to the glue, and mix it until the glue has a uniform color. This will take some time. (optional). 2. Add the Elmer’s Glue to the Borax and water solution. 3. Vigorously mix together the glue and borax water mixture with your fingers while keeping the polymerizing glue “silly putty” in the borax water solution. Every now and then, pull the blob of glue/silly putty out of the borax water and kneed it up and see if any pockets of liquid glue still exist. If you see liquid glue squirting out of the “silly putty”, then it has not yet fully reacted with the borax water. Put it back into the solution and kneed it up some more. 5. Once it has fully reacted, pull it out of the solution and gently pat it dry with a paper towel. 6. Store it in a zip-lock plastic storage bag to keep it from drying out. If it gets into clothes or hair, it can be easily washed out with warm water. The starting glue and “silly putty” are environmentally safe and biodegradable. Name ______________________ Date ____________ Analysis: Create a brief lab report using Comic Life to document your work. Your analysis should be no more than one page, and should include the following. 1. List your group members 2. Include a photograph of your polymer 3. List the chemical elements in borax and glue by name and by element symbol. (Example: Carbon C ) 4. Describe the physical properties of the glue and the borax solution before you mixed them together. 5. Describe the physical properties of the polymer after the glue and borax were added together? 6. Did you observe a chemical reaction? If so, what chemical changes do you think occurred in this experiment? Once you have completed your analysis, choose “File”, “Export”, “Export to Image” and save your analysis as a jpeg image file. Submit your image through the hand in robot – one per group. Some Examples of Polymers: polypropylene, polystyrene, polyvinylchloride, Kevlar, Mylar, Neoprene, Nylon, Orlon, Teflon, …