Plastics the Second Time Around

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In this activity, learners test and compare the physical properties of thermoplastic polymers. Learners compare different plastics based on their color, degree of transparency, texture, and density. Use this activity to discuss why some plastics can be recycled and others cannot. Safety note: Educators should read the "General Safety Guidelines."

Quick Guide

Preparation Time:
10 to 30 minutes

Learning Time:
30 to 45 minutes

Estimated Materials Cost:
$1 - $5 per group of students

Age Range:
Ages 14 - adult

Resource Type:
Experiment/Lab Activity


Materials List (per group of students)

  • Samples of plastics such as high density polyethylene, low density polyethylene, polyethylene terephthalate, polypropylene, polystyrene, or polyvinyl chloride
  • 52% ethanol (density = 0.911)
  • 38% ethanol (density = 0.9408)
  • 24% ethanol (density = 0.9549)
  • 6% CaCl2 (density = 1.0505)
  • 32% CaCl2 (density = 1.3059)
  • 40% CaCl2 (density = 1.3982)
  • 250 ml beaker


  • Engineering and Technology
    • Engineering
      • Chemical Engineering
      • Environmental Engineering
      • Metallurgy and Materials Engineering
  • Life Sciences
    • Ecology
      • Human Impact
  • Physical Sciences
    • Heat and Thermodynamics
      • Heat and Temperature
    • Chemistry
      • Chemical Reactions
    • Structure and Properties of Matter
      • Volume and Density
  • The Nature of Technology
    • Technology and Society
      • Technology and the Environment

Informal Categories

  • Nature and Environment


To use this activity, learners need to:

  • see
  • see color
  • touch

Learning styles supported:

  • Uses STEM to solve real-world problems
  • Involves hands-on or lab activities


Components that are part of this resource:

This resource is part of:

Access Rights:

  • Free access


Funding Sources:

  • National Science Foundation Education and Human Resource Directorate, ESI 92-53386
  • National Science Foundation Center for Advanced Cement Based Materials
  • Dow Chemical Foundation
  • Materials Research Society
  • Iron and Steel Society
  • Peoria Chapter of the American Society for Metals