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Plastics and Composites

Plastics and Composites. H H. H H. C=C. H H -C-C- H H. ···. ···. Welding of Plastics. Polymers. Polymer - a single building block (mer) is repeated to form a long chain molecule Thermoplastic polymers soften when heated, harden when cooled 2-liter bottles

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Plastics and Composites

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  1. Plastics and Composites

  2. H H H H C=C H H -C-C- H H ··· ··· Welding of Plastics Polymers • Polymer - a single building block (mer) is repeated to form a long chain molecule • Thermoplastic polymers soften when heated, harden when cooled • 2-liter bottles • Thermosetting polymers don’t soften when heated • Car tires, caulking compound (Poly)ethylene add H2O2

  3. Curing of Polymers • Types of Thermoset Polymers • Anaerobic Cyanoacrylates • Epoxies Urethanes • Silicones • Thermosets form long polymer chains by chemical reaction (curing) • Heat is the most common means of curing • Ultraviolet light, oxygen - acrylics • Moisture – Cyanoacrylates (superglue) 0.1.1.2.6.T26.95.12

  4. Moffatt, Pearsall, & Wulff, “The Structure and Properties of Materials”, John Wiley & Sons.

  5. Curing of Polymers • Thermoplastics (hotmelts) • Adhesive is heated until it softens, then hardens on cooling -Polyethylene, PVC 0.1.1.2.6.T26.95.12

  6. Materials, Scientific American Book, W.H. Freeman & Company

  7. 1 B D A 2 C 3 Materials, Scientific American Book, W.H. Freeman & Company

  8. Cautions • Some older tests for plastic recognition suggested burning of the polymer and noting its flame and smell. Some materials can emit harmful vapors so this is not recommended for a class exercise, and should be done only under controlled conditions. • Any heat applied to a plastic should be done in a ventilating hood.

  9. Composite Materials Wood Cross Section Materials, Scientific American Book, W.H. Freeman & Company

  10. Composite Fiber Properties Stiffness Strength Materials, Scientific American Book, W.H. Freeman & Company

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