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PE 335: Polymer Science and Engineering I

Professor Abdelsamie Moet Fall 2013/14. PE 335: Polymer Science and Engineering I. Definitions and Classifications. Learning. Polymer Basis of Classifications Thermoplastics and thermosets Recycling Codes Natural Polymers Chain Microstructure. What are Polymers?.

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PE 335: Polymer Science and Engineering I

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  1. Professor Abdelsamie Moet Fall 2013/14 PE 335: Polymer Science and Engineering I Definitions and Classifications

  2. Learning • Polymer • Basis of Classifications • Thermoplastics and thermosets • Recycling Codes • Natural Polymers • Chain Microstructure

  3. What are Polymers? • Greek word Poly = many; Mer = unit  Polymer = many units • The term polymer denotes a molecule made up by the repetition of smaller molecules, the monomer. • The repeating structure is mostly based on a carbon backbone.

  4. monomer monomer Examples Polyethylene (PE) Poly(vinyl chloride) (PVC)

  5. Classifications • Origin • Natural • Man-made (synthetic) • Thermal • Thermoplastic • Thermosets • Synthetic Route • Addition • Condensation • Ring-opening • Chain Microstructure • Homopolymer • Copolymer • Applications • Commodity • Engineering • Aerospace • Medical • Automotive • Agricultural • etc

  6. Thermoplastics: - ‘Plastics’ - By far the greatest percentage of polymers are thermoplastics - PS, PE, PP, PVC… Linear Chains ‘recyclable plastics’… - Thermoplastics melt and flow upon heating - Can be injection molded, extruded, etc. into shapes and parts… …and re-melted and re-molded, and… recycled. Thermosets: Cross-linked Chains Do not melt and do not flow Upon heating - Melamine Formaldehyde ‘not readily recyclable plastics’…

  7. Recycling Codes for Common Thermoplastics

  8. Natural Polymers Silk Wool Cotton Wood Rubber

  9. Silk • Silk is made up of the amino acids GLY-SER-GLY-ALA-GLY and forms Beta pleated sheets. • Silk is produced by silkworms and spiders.

  10. Wool is keratin, a protein copolymer containing about 17 different amino-acid monomers. The rather strong disulphide bonds (-S-S-) are supplemented by weaker hydrogen bonds between -NH- and -CO- groups of adjacent keratin chains, ion-ion interactions between amino groups. Wool

  11. Cotton • The chemical composition of cotton, when picked, is about 94 percent cellulose; in finished fabrics is it 99 percent cellulose. • n is in the range of 10,000 glucose monomers per molecule. The molecular chains are arranged in long spiral linear chains within the fiber.

  12. Wood

  13. Natural rubber’s scientific name is polyisoprene. The most common source is the rubber tree (Hevea brasiliensis), grows in Brazil, East Asia and tropical Africa.  Natural Rubber

  14. How Large is a Polymer Molecule? EthyleneCH2=CH2 Polyethylene-(CH2-CH2)n Then because there are only 200 ethylene units in this chain (i.e., it is a 200-mer), its molecular weight is only 5,600 (=28 x 200).

  15. Distribution of Polymer Chains

  16. Molecular weight and dispersion Syntetic polymers always show a distribution in molecular weights. number average : weight average: (ni and wi are number and weight fractions, respectively, of molecules with molar mass Mi) The polydispersity index is given by Mw /Mn

  17. Molecular weight and dispersion -an example: Here are: 10 chains of 100 molecular weight 20 chains of 500 molecular weight 40 chains of 1000 molecular weight 5 chains of 10000 molecular weight

  18. Chain Microstructure Chain Microstructure Chemical Structure

  19. Chain Microstructure

  20. Morphology

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