Chemistry of Chemistry of Organic Polymers Organic Polymers

and Recyclingand Recycling

Taz ChoudhuryChem 481

March 2nd, 2006

Organic Polymers

A macromolecule which is made of structurally similar monomers repeatedly connected by covalent bonds.

Three main groups of polymers-1. Thermoplastics- linear or branched chains, readily melted and molded

into any shape.2. Thermosets- cross-linked chains, once they’re molded or cured it cant

be re melted or remolded. 3. Elastomers- amorphous polymers that can stretch and rebound;

usually crosslinked by covalent bonds.

Chemically inert; not attached by air or its pollutantsVery stable towards water

Molecular Classification

Chain Growth Polymerization

Butyl lithium

Step 2- Initiation

Step 3- Repeat

Step Growth PolymerizationStart with

Step 1- Transesterification

Step 2- ester intermediate

Making PolyesterStep 3- formation of ethyl terephthalate

Step 3- formation of bis(2-hydroxyethyl) terephthalate

Final-

After the bis(2-hydroxyethyl)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!!

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

PlasticsClassified 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 lifePolystyreneStyrofoamPVCNylonTeflon

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 problemThermoplastics products can be remelted and reused and

thermoset plastics can be ground up and used as fillers.

Problems with recycling plasticsAutomation of sorting of plastic wasteUnlike 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?