Objectives
After participating in the program Materials and the Environment, Part 3, students will be able to:

· describe the codes use to classify recyclable polymers

· explain density

· sort objects based on their relative densities

· demonstrate that physical properties can be used to sort different materials

Vocabulary

*recycling	to use again and again
*polymers	giant molecules built from thousands of smaller molecular units that are repeated in a pattern
*density	the ratio of the mass of an object to its volume
*surface tension	an energy associated with a surface or interface between two different materials (such as liquid and air)

Materials
(For each group)
        · plastic cups or beakers (size is unimportant as long as the plastic samples fit easily) for each solution used
        · polymer samples
                - PETE
                - HDPE
                - V
                - LDPE
                - PP
                - PS
        · craft stick
        · liquids
                - distilled water
                - vegetable oil
                - glycerin
                - alcohol/water mixture
                - 7.8% "Mono Lake" salt water5 (2000 value)
                - 3.6% "sea" salt water4
        · markers

Total  Activity Time: 1 Hour 30 Minutes

~~

Disclaimer: Most of the procedures for the activities contained in the lessons have been adapted from various resources listed throughout the module.

This work was supported by the Center on Polymer Interfaces and Macromolecular Assemblies (CPIMA)
as part of the NSF Materials Science and Engineering Center program under Grant DMR 9808677

Copyright 1996 - 2003, Leland Stanford Junior University. All rights reserved.

 

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