Transcript Dacron - North Seattle College

Dacron
Sanaz Leilabadi and Linda Edwards
Get to know Dacron
• Trade name for Polyethylene Terephthalate
aka PET, PETE, PETP
• Polyethylene Terephthalate is a resin of the
polyester family that is used to make beverage,
food and other liquid containers, synthetic fibers
• Clear, tough plastic with good gas and moisture
barrier properties
Chemically Speaking
Condensation Polymer
Polyethylene terephthalate is synthesized
by transesterification of two monomers:
Ethylene glycol and Dimethyl terephthalate
+
Transesterification is used in the synthesis
of polyester, in which diesters undergo
transesterification with diols to form
macromolecules. In our case, dimethyl
terephthalate and ethylene glycol react to
form polyethylene terephthalate and
methanol, which is evaporated to drive the
reaction forward.
Catalysts
• Transesterification reactions are often catalyzed
by the addition of an acid or base.
• Acids can catalyse the reaction by donating a
proton to the alkoxy group, thus making it more
reactive, while bases can catalyse the reaction
by removing a proton from the alcohol, thus
making it more reactive.
Polymer
Mechanism of Polymerization
History of Dacron
• PET: originally patented by British chemists
– John Rex Whinfield and James Tennant Dickson in
1941 after early research by Wallace Carothers
• Dupont used its nylon technology to improve the
polyester fiber that was patented by the British
• Dacron was created in 1950 by Dupont
What IS Dacron?
• A polyester fiber used in clothing.
• A yarn used in:
curtains
dress fabrics
high pressure fire hoses
men’s shirts
threads.
Dacron Products
• Boat sails
• Antenna rope
• Climbing ropes
• Foam covers
• Carpets and textiles
• Furniture
• Luggage
Where can we find it?
Dacron in Medicine
• Cardiothoracic and Vascular grafts and implants
– Aneurysm repair
(Thoracic and Abdominal Aorta)
– Patch Angioplasty
– Vascular grafts
• Strong, flexible and treated
with collagen to keep blood
from soaking through
• Chemically inert and thus well
tolerated inside the body
Dacron- Then and Now
• Dacron has come a long way since 1950
• More commonly used today thanks to new
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technology
Price range varies depending on the product it
as been made into
Intrinsic viscosity (thickness) of ~0.60 (fibers)
– PET can range up to ~0.85 for tire cord
Recycling Dacron
• Methanolysis is an example
of reverse transesterification
and has been used to recycle
polyesters into individual
monomers
• Fully recyclable- when needed
• Its polymer chains can be
recovered for reuse.
Health Effects
• One study showed that after imbedding polymer
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films of Dacron in rodents there was evidence of
some malignant tumor formation, study was
later deemed inadequate
Further research shows no short term or long
term toxicity with use of Dacron
However, strong evidence of nausea, vomiting,
central nervous system paralysis and kidney
damage with prolonged exposure to ethylene
glycol
Dacron Properties
• High tensile strength, high resistance to stretching, both
•
wet and dry, and good resistance to degradation by
chemical bleaches and to abrasion which is why it is
preferred for surgical use
High melting temperature of 496 degrees Fahrenheit
(256 degrees Celsius), due to cross-linkage in synthesis
of the fiber.
For more information
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http://www.elmhurst.edu/~chm/vchembook/402condensepolymers.html
http://www.bicuspidfoundation.com/Aortic_Aneurysm_and_Dissection.html
http://www.bartleby.com/65/da/Dacron.html
http://www.nlm.nih.gov/medlineplus/ency/article/002345.htm
http://md1.csa.com/partners/viewrecord.php?requester=gs&collection=TRD&recid=C
A6703713WC
http://education.yahoo.com/reference/encyclopedia/entry/Dacron
http://www.me.berkeley.edu/ME117/S05/finalproject/pdf/Vascular_Graft.pdf
http://www.alibaba.com/productsearch/Adhesive_Paper/10.html
http://www.surgical-tutor.org.uk/default-home.htm?tutorials/graft.htm~right
http://www.texdev.com/sld007.html
http://en.wikipedia.org/wiki/Dacron
Questions
Discussion