oxidation (thermal and light-catalyzed) hydrolysis (ester backbone polymers) loss of polymer...

Download Oxidation (thermal and light-catalyzed) Hydrolysis (ester backbone polymers) Loss of polymer components (e.g. plasticizer) Stable (incl. outdoor) Poly(methyl

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  • Slide 1
  • Slide 2
  • Oxidation (thermal and light-catalyzed) Hydrolysis (ester backbone polymers) Loss of polymer components (e.g. plasticizer) Stable (incl. outdoor) Poly(methyl methacrylate) Bisphenol polycarbonate Poly (vinyl fluoride) Scratch-resistant coating Sensitive to UV Aromatic polyurethanes (aliphatic more stable) Sensitive to Oxidation Polyolefins Stabilizers
  • Slide 3
  • General Mechanism of Oxidation Chain Reaction Backbiting in Polymers
  • Slide 4
  • General mode of action formation of weak radicals Examples 1. Aromatic amines (most active) R aliphatic/aromatic Electron delocalization stabilizes radicals Disadvantages: staining antioxidants
  • Slide 5
  • 2. Hindered phenols http://patentimages.storage.googleapis.com/US20020142923A1/US20020142923A1-20021003-C00002.png https://www.dispersions-pigments.basf.com/portal/streamer?fid=560036 Disadvantages: good for gasoline, too volatile for use in plastics
  • Slide 6
  • Higher molecular weight hindered phenols Nitrogen-containing phenols (more effective) Dinitriles
  • Slide 7
  • -Contain S(II), S(IV), P(III) - Act differently than antioxidants - Synergetic with antioxidants, used together
  • Slide 8
  • Propylenediamine - Work by metal sequestration Salpn EDTA Citric Acid
  • Slide 9
  • -Encapsulation of electroluminescent polymers on resins -Addition of carbon black as a pigment -UV screening agents
  • Slide 10
  • Natural phenols from plants (rosemary, black papper, buckweat, peanut halls) Vitamin E Plant flavanoids (epigallocatechin gallate)
  • Slide 11
  • What are lubricants? What is their function? When lubricants are not needed: -Bearings suspended by pressurized gas -Nylon and polytetrafluoroethylene (PTFE, Teflon ) polymers Substances used as lubricants or lubricant alternatives -Carbon-graphite -Polymer cross-linking improves abrasion resistance -Silicon oil -Zirconium particles -MbS 2 -WS 2
  • Slide 12
  • -Coatings of polyurethane rubber, ultralight polyethylene (metal surfaces) -Making surface harder (cross-linked coatings) - Layer of silica or titania -High energy ion irradiation of polyethylene, nylon, polystyrene, etc -Diamond coating (vapor deposition)

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