Transcript Chemistry of Organic Polymers and Recycling

Chemistry of Organic Polymers
and Recycling
Taz Choudhury
Chem 481
March 2nd, 2006
Organic Polymers
A macromolecule which is made of structurally similar monomers
repeatedly connected by covalent bonds.
Three main groups of polymers1.
2.
3.
Thermoplastics- linear or branched chains, readily melted and
molded into any shape.
Thermosets- cross-linked chains, once they’re molded or cured it cant
be re melted or remolded.
Elastomers- amorphous polymers that can stretch and rebound;
usually crosslinked by covalent bonds.
Chemically inert; not attached by air or its pollutants
Very stable towards water
Molecular Classification
Chain Growth Polymerization
Butyl lithium
Step 2- Initiation
Step 3- Repeat
Step Growth Polymerization
Start with
Step 2- ester
intermediate
Step 1- Transesterification
Making Polyester
Step 3- formation of ethyl terephthalate
FinalAfter the bis(2hydroxyethyl)terepthalate is
formed, it continues with
more transesterifications
until the product gets bigger
and bigger. When the
molecular weight is large
enough, it turns into
poly(ethylene terephalate or
PET. POLYESTER!!
Step 3- formation of
bis(2-hydroxyethyl)
terephthalate
Physical Properties
Melting point- does not occur over a sharp
temperature range because of its size.
– The range can be as much as 50-65 deg C over which the
viscosity of the polymer changes its state.
Boiling Point- Polymers never boil
Solubility- Most polymers are insoluble in water; some are
soluble only with strong organic solvents
Plastics
Classified according to their polymer backbone (polyvinyl
chloride, polyethylene, silicone)
Since they are partially crystalline and partially amorphous
in molecular structure, they have a melting point
Plastics take many forms to be useful in our everyday life
Polystyrene
Styrofoam
PVC
Nylon
Teflon
Problem
The remarkable versatility and usefulness of
plastic comes with a very high price.
They are durable and degrade very slowly
Burning plastics releases toxic fumes in the air that
are harmful to humans, plants and animals
The large amounts of chemicals used to produce
and dispose of plastic materials require the use
of our already limited supply of fossil fuels.
Despite all the problems plastic has posed on our
society today, THERE IS GOOD NEWS…
Recycle!
Recycling plastic products is a easy and effective solution
to the problem
Thermoplastics products can be remelted and reused and
thermoset plastics can be ground up and used as fillers.
Problems with recycling plastics
Automation of sorting of plastic waste
Unlike metal, a lot of plastics have to be manually sorted (movie)
Recycling certain types of plastic is unprofitable
Q: What percentage of plastics are recycled in the US
every year?
Resin ID Code
How Recycling Works
Future
“Product Stewardship
Program”
Produce DeskJet
printers from
recyclable plastics.
Diverts as much as six
million pounds of
plastics from landfills
by only using 25%
recyclable plastic!
Conclusion
• Organic polymers, have been our best friend
throughout history due to its physical and
chemical properties.
• The problems, however, we face due to our
increasing use of plastics, made from organic
polymers, are posing to be a challenge
• Recycling these products seems to be the
optimal solution to some of the issues and thus
many organizations and scientists are working
on making it an essential part of our lives.
Citations
• ‘Polymers: Chemistry & Physics of Modern Materials,’ 2nd Edition,
J.M.G. Cowie, 1991
• ‘Encyclopedia of Polymer Science’ Wiley, 1997
• ‘Comprehensive Polymer Science: The Synthesis, Characterization,
Reaction, and Applications of Polymers’, G Allen and J.C.
Bevington, 1989
• H. Choong, “Procurement of Environmentally Responsible Material”,
IEEE International Symposium on Electronics and Environment,
May 1996
• V. Ross, “HP DeskJet Printers with Recycled Plastics”, 1996
Questions?