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Chemical and Physical Properties. MFG 355. Ultraviolet (UV) Light Degradation. Oxidation. Plastic paint. Chemical resistivity and solubility. Dissolving. None. Reacting. Swelling/softening. Nylon and H 2 O PVC and ketone. PVOH and water. Cellulosics and acids. PE and H 2 O.

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Presentation Transcript
oxidation
Oxidation
  • Plastic paint
chemical resistivity and solubility
Chemical resistivity and solubility

Dissolving

None

Reacting

Swelling/softening

Nylon and H2O

PVC and ketone

PVOH and water

Cellulosics

and acids

PE and H2O

Increasing Chemical Reactivity to Plastic

chemical nature and solvent solute interactions
Chemical Nature and Solvent-solute Interactions
  • Polar effects
    • Like with like
  • Steric effects
    • Crystallinity
  • Physical property effects on solvent-solute interactions
    • Solvent size
    • Swelling
thermodynamics of solvent interactions
Thermodynamics of Solvent Interactions
  • Equation

ΔG = ΔH – TΔS

      • Negative ΔG is favorable
      • Negative ΔH means bonds are forming
      • Positive ΔS is standard (increasing)
    • When does each term dominate to give a negative ΔG?
plasticizers
Plasticizers
  • Increase swelling
    • Randomness
  • Plasticizers can migrate out
water repellent
Water Repellent
  • Surface tension must be LOW
    • Silicones = 24 dyne/cm
    • PTFE = 19 dyne/cm
    • PVC = 37 dyne/cm
  • Water wicking
corrosion resistant
Corrosion-Resistant
  • Availability of electrons
  • Polymers are better than metals
  • Fluoropolymers—tightly attached
    • Electron shielded
  • Chlorine attachment (blocks electron availability)
coatings
Coatings
  • Decorative and protective
    • Adhesion
    • Weatherability
    • Water solubility
environmental stress cracking
Environmental Stress Cracking
  • Hawaii Story
    • Crosslinked, LLDPE
  • Banana Plantation
    • Drawdown
crazing
Crazing
  • Cracks at stress areas
permeability
Permeability
  • Diffusion Coefficient
    • D = Doe-A/RT
  • Fick’s Laws of diffusion
    • J = -D dc/dx
  • Barrier Properties
    • dc/dt = D d2c/dx2
gas vapor permeation
Gas (vapor) Permeation
  • Polar groups (solubility) to solvent or gas
  • Intermolecular size (distance)
  • Crosslinking and crystallinity
electrical properties
Electrical Properties
  • Resistivity (1018 – 10-6)
  • Dielectric Strength
  • Arc Resistance
  • Dielectric Constant
  • Dissipation Factor (heat up)
optical properties
Optical Properties
  • Light Transmission
    • Clear
    • Translucent
    • Opaque
  • Colorants
    • Dyes
    • Pigments
  • Surface Reflectance
transparency
Transparency
  • Non-crystalline
  • Index of refraction – low
  • Total luminous transmittance – high
flammability
Flammability
  • Self-extinguishing
    • Halogen effects (oxygen)
    • Fillers (Al2O3·3H2O) (heat)
    • Aromatics (fuel)
    • Silicones (fuel)

Heat

Fuel

Oxygen

flammability tests
Flammability Tests
  • Vertical and horizontal burn tests
slide27

Chamber

Sample

Sample holder

Gas manifold

N2

O2

Limiting Oxygen Index

flammability tests28
Flammability Tests
  • Radiant panel
  • Cone calorimeter
flexibility
Flexibility
  • CH2, O are flexible
    • PE, Polyisoprene, PEO, Siloxanes
  • Polybutylene terephthalate is more flexible than PET
  • Pendant groups
  • Crystallinity – reduces flexibility
  • Copolymers
  • Plasticizers (soluble)
heat resistance
Heat Resistance
  • Stiffening groups along the chain
    • Phenyl groups
    • Tggoes up since it takes more heat to move molecules
  • Strong intermolecular H-Bonding
  • Crystallinity increases heat resistance
insulating polymers
Insulating Polymers
  • Non-polar is better
  • Foams
    • Air is an insulator
toughness
Toughness
  • Backbone Structure
  • Pendant Groups
flammability tests34
Flammability Tests
  • Limiting oxygen index (LOI)
adhesives
Adhesives
  • Bonding (chemical) between surfaces is best
  • Crosslinking agents (ie siloxanes)
  • Solvent based
  • Latex adhesives – good flow into crevices for mechanical attachment
  • Pressure-sensitive – polymer flow (mechanical)
  • Hot melt – polymer flow
  • Reactive – low molecular weight to get stronger
  • End Groups