Cross-Linking+Polymers+To+Make+Super+Balls

Cross-Linking Polymers to Make a Super Ball. **John Hill and Carter Peterson.** The purpose of this lab was to experiment with and investigate cross-linking various polymers with the goal of producing a rubbery, homogeneous, spherical ball capable of bouncing off a hard surface. Trials 1 through 7 involved cross-linking polymers of aqueous sodium silicate together using molecules of ethanol. Trial 8 cross-linked the natural polymer cornstarch and the alternating co-polymer of polyvinyl alcohol and polyvinyl acetate with borate ions from a 0.22 molar solution of aqueous sodium borate. Trials 9 and 10 cross-linked polyvinyl alcohol and cornstarch with borate ions from a 0.22 molar solution of aqueous sodium borate. Trials 11-21 cross-linked polyvinyl alcohol and gelatin with borate ions from a 0.40 molar solution of aqueous sodium borate. Trials 1 through 7 produced a small amount of rubbery precipitate that dried into a crumbly powder. Trial 8 was quite sticky until it dried into an extremely hard ball. Trials 9 and 10 formed a silly putty like substance, 9 was slightly more moist than 10. Trials 11 through 21 formed various rubbery substances. Trial 20 was formed into a ball an exhibited all the characteristics of a super ball. Trial 21 was then used to support the results of Trial 20 and demonstrate a lack of any significant error in producing trial number 20. (Keywords: polymer, homo-polymer, co-polymer, molarity, precipitation, cross-linking)
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 * LAB SETUP:**


 * Our Recording:** media type="file" key="science project.mp3" width="97" height="43"

Crosslinking. []. (Accessed 2010 February 16).

Ophardt, C. (2003). //Silicone polymers//. Unpublished manuscript, Department of Chemistry, Elmhurst College, Virtual Chembook. Retrieved from http://www.elmhurst.edu/~chm/vchembook/404silicone.html