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Synthetic condensation polymers - Urea- methanal & Kev l ar

Synthetic condensation polymers - Urea- methanal & Kev l ar. Group members: Vincci Lau (17) Jojo Lau (18) Kelly Ma (25) Hilton Tai (29) Polly Wong (35). Urea-methanal. Introduction Urea formaldehyde white thermosetting plastic condensation polymer Functional group:

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Synthetic condensation polymers - Urea- methanal & Kev l ar

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  1. Synthetic condensation polymers - Urea-methanal & Kevlar Group members: Vincci Lau (17) Jojo Lau (18) Kelly Ma (25) Hilton Tai (29) Polly Wong (35)

  2. Urea-methanal • Introduction • Urea formaldehyde • white thermosetting plastic • condensation polymer • Functional group: • aldehyde (-CHO) • amine (-NH2) • amide

  3. Urea-methanal • Properties • high tensile strength • flexural modulus • heat distortion temperature • low water absorption • high surface • volume resistance

  4. Formation of urea-methanal • heating urea and methanal with a catalyst (e.g. ammonia or pyridine )

  5. Uses of urea-methanal • electrical switches • electrical appliance casing (e.g. desk lamp) • plugs, sockets

  6. heat-resistance kitchen ware • laminated sheet for furniture • preservative for the biological and anatomical specimens

  7. Kevlar • Introduction • similar in structure to nylon-6,6 • except that instead of the amide links joining chains of carbon atoms together, they join benzene rings • thermoplastic polyamide • very crystalline polymer • high melting point • nearly insoluble in most solvents object:

  8. Kevlar • Two polymers • benzene-1,4-dicarboxylic acid • 1,4-diaminobenzene Structure: -NH-C6H4-NHCO-C6H4-CO-

  9. Kevlar line these up and remove water between the -COOH and -NH2 groups in the same way as we did with nylon-6,6, you get the structure of Kevlar

  10. Formation of Kevlar • Synthesized from solution of monomers 1,4-phenylene-diamine (para-phenylenediamine) and terephthaloyl chloride • This is a condensation reaction • HCl is released as a byproduct

  11. The result of the reaction has liquid-crystalline behavior, and mechanical drawing orients the polymer chains in the fiber's direction.

  12. Applications of Kevlar • gloves, sleeves, jackets, chaps • sports equipment like as an inner lining

  13. marching snare drums • The fiber made from Kevlar is used in woven rope and in cable. • protective • outer sheath for optical fiber cable.

  14. combat helmets, Ballistic face masks and Ballistic vests.

  15. Properties of Kevlar • High mechanical strength and hardness • long polymeric chains with a parallel orientation (high density) • intra-molecular hydrogen bonds (between the carbonyl groups and NHcenters) • Dashed: hydrogen bonds

  16. Properties of Kevlar • High mechanical strength and hardness • phenyl stacking interactions (between adjacent strands) • (see fig. below) • stronger than the van der Waals interaction • consists of relatively rigid molecules • form a planar sheet-like structure similar to silk protein.

  17. Properties of Kevlar • High mechanical strength and hardness • Crystallinity • manufacturing process known as spinning • involves extruding the molten polymer solution through small

  18. Properties of Kevlar • High mechanical strength and hardness • Polyaromatic amide • contains aromatic and amide groups • high degree of symmetry and regularity to the internal structure of the fibers

  19. Properties of Kevlar • Good wetting properties • polar groups hydrogen bonding • when water enters the interior of the fiber • take the place of bonding between molecules • reduce the material's strength • available groups at the surface lead to good wetting properties • feel more nature and “sticky” • Heat resistance (decomposes above 400 °C without melting) • highly unsaturated (high density)

  20. Impacts of the development of polymers on our society • Benefits • most used material in the world since 1976 • provide improved packaging • giving us new textiles • permit the production of new products and technologies e.g. televisions, cars and computers.

  21. Harm • abuse of plastic • commercial plastic wrappings, plastic liquid containers, plastic agricultural membranes •  use-and-dump material • Since the 1950s, one billion tons of plastic have been discarded

  22.  toxicity of plastic • plastics often contain a variety of toxic additives, e.g. plasticizers • compounds leaching from polystyrene food containers interfere with hormone functions and are suspected human carcinogens. • monomers used, e.g. chloride vinyl, may be toxic; and may remain trapped in the product.

  23. Environmental issues • Plastics are durable and degrade very slowly • burning plastic can release toxic fumes • manufacturing of plastics creates chemical pollutants. • Plastic waste constitues about 7% of household waste. Landfill sites are used up • Low possibility of recycling because of the high cost

  24. END

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