Effect of UV Light on Standard Plastic and Bio-Plastic Bags

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Effect of UV Light on Standard Plastic and
Bio-Plastic Bags

• By Anthony Disbrow, and Tyler Ista
• ENG 45
• SRJC
• 12/13/06

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Factors

• Reflection
• Ambient temperature
• Humidity
• Impurities

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Effects

• Any UV radiation can cause photochemical effect
  within polymers.
• This effect can be either a benefit, or a
  detriment.
• With respect to plastics, UVC is more likely to
  have an effect.
• Surface of plastics may undergo a color shift,
  appear chalky, or become brittle.

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Effects Continued

• Certain polymer systems are able to be cured
  under UV light at room temperature.
• UV curing can also be used on some glasses,
  semiconductors, optical fibers, dental fillings,
  inks, paper finishes, and much more.
• UV curing can take place in a matter of seconds.

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What Happens

• UV energy can excite photons, which result in
  free radicals (atoms or molecules with un-paired
  electrons).
• Small impurities (ppb) can act as free radical
  receptors, leading to degradation.

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Plastic Statistics

• One ton of recycled plastic saves
• 5,774 Kwh of energy
• 16.3 barrels (685 gallons) of oil
• 98 million Btu's of energy
• 30 cubic yards of landfill space
• Recycled plastic saves 88 of the energy used to
  produce plastic from raw materials.
• Only 26 of HDPE plastic are recycled
• Plastics cannot be naturally degraded.

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• No polyethylene is used .
• Made from cornstarch, vegetable oil and other
  renewable resources.
• The Mater-Bi process is protected by more than 70
  patents.
• Compostable, disposable

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Procedure

• Cut plastic bag into a strip 1 x 12.
• Record initial thickness using micrometer.
• Record initial width with Verneir calipers.
• Clamp one end of bag allowing the strip to hang.
• Clamp the other end such that weights can be hung
  from the clamp.
• Measure the initial length of the specimen.
• Add weight in 50g increments, record the length
  after each increment.
• Continue the previous step until the specimen
  breaks.
• After breakage record the final length, thickness
  and width.

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Kirkland Biobag Kirkland Biobag
Toughness (Mpa) 9.24 2.4 Area Reduction 91.81 53.52
Yield Strength (Mpa) 7.9 6.6 Elongation 49.55 55.93
UTS (Mpa) 10.64 7.17 Modulus (Mpa) 53.56 43.9
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Toughness (MPa) 31 Area Reduction 67.68
Yield Strength (MPa) 5.64 Elongation 214.64
UTS (MPa) 14.77 Modulus of Elasticity (MPa) 71.2
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Toughness (Mpa) 33.90 Area reduction 38.62
Yield Strength (Mpa) 8.26 Elongation 25.13
UTS (Mpa) 10.23 Modulus of Elasticity (Mpa) 296.90
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Thoughness (MPa) 20.4 Area reduction 65.24
Yeild Strength (MPa) 5.72 Elongation 151.79
UTS (MPa) 9.04 Modulus of Elasticity (MPa) 71.44
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Toughness (MPa) 0.357 Area reduction 0
Yield Strength (MPa) NA Elongation 0.19
UTS (MPa) 12.07 Modulus of Elasticity (MPa) 471.5
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Test Setup
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The End Result
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Conclusions

• Just the tensile test alone was not enough to
  reach a solid conclusion.
• The creep properties of the plastic appeared to
  be affected.
• The stress strain curve alone cannot show the
  elongation for a given time period.
• We observed the samples exposed to more UV light
  crept the slowest.

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Sources

• http//www.zeusinc.com/cgi-bin/search.exe?qUV
• http//www.masterbond.com/wbarticles/wbuv.html
• http//en.wikipedia.org/wiki/Ultraviolet
• http//www.biogroupusa.com/catering.htm
• http//www.biobag.at/produkte/bio_bag/bag_4_life/
• http//www.greenerchoices.org/products.cfm?product
  plasticpcathomegarden
• http//www.deq.state.ms.us/MDEQ.nsf/page/Recycling
  _RecyclingTrivia?OpenDocument