Chemistry of Organic Polymers and Recycling Taz Choudhury Chem 481 March 2 nd, 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 pollutants Very stable towards water

Molecular Classification

Chain Growth Polymerization Butyl lithium Step 2- Initiation Step 3- Repeat

Step Growth Polymerization Start with Step 1- Transesterification Step 2- ester intermediate

Making Polyester Step 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 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,’ 2 nd 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?