If you like us, please share us on social media.
The latest UCD Hyperlibrary newsletter is now complete, check it out.

ChemWiki: The Dynamic Chemistry E-textbook > Development Details > Approaches > Demos > Additional Demos > Smart Balls/ Stupid Balls

Copyright (c) 2006-2014 MindTouch Inc.

This file and accompanying files are licensed under the MindTouch Master Subscription Agreement (MSA).

At any time, you shall not, directly or indirectly: (i) sublicense, resell, rent, lease, distribute, market, commercialize or otherwise transfer rights or usage to: (a) the Software, (b) any modified version or derivative work of the Software created by you or for you, or (c) MindTouch Open Source (which includes all non-supported versions of MindTouch-developed software), for any purpose including timesharing or service bureau purposes; (ii) remove or alter any copyright, trademark or proprietary notice in the Software; (iii) transfer, use or export the Software in violation of any applicable laws or regulations of any government or governmental agency; (iv) use or run on any of your hardware, or have deployed for use, any production version of MindTouch Open Source; (v) use any of the Support Services, Error corrections, Updates or Upgrades, for the MindTouch Open Source software or for any Server for which Support Services are not then purchased as provided hereunder; or (vi) reverse engineer, decompile or modify any encrypted or encoded portion of the Software.

A complete copy of the MSA is available at http://www.mindtouch.com/msa

Smart Balls/ Stupid Balls

Chemical Concepts Demonstrated

  • Copolymerization
  • Cross-linking


These two (apparently) similar balls are bounced. balls.gif


One ball bounces significantly higher than the other.


The "hard" (smart) ball is made up of polybutadiene to which an unusually large amount of sulfer has been added (up to 15 parts of sulfur per 100 parts of polybutadiene).  There is extensive cross-linking involved in this polymer, so it dissipates very little energy in the form of heat when it bounces.

The "soft" (stupid) ball is a block co-polymer, such as poly(styrene-butadiene) or poly(vinyl-butadiene).  It has very little significant resiliance.   It should be noted that poly(styrene-butadiene) is used for automobile tires, which absorb some of the energy associated with the bumps along the highway.



Last modified
10:29, 2 Oct 2013



(not set)
(not set)

Creative Commons License Unless otherwise noted, content in the UC Davis ChemWiki is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License. Permissions beyond the scope of this license may be available at copyright@ucdavis.edu. Questions and concerns can be directed toward Prof. Delmar Larsen (dlarsen@ucdavis.edu), Founder and Director. Terms of Use