CHEM 210SPRING 2014DR. VILCHIZ

POLYMERS

Brief History

Ca. 1600 BC Earliest known polymer work Pre-Columbian Mexico’s rubber industry

Latex from the rubber tree + juice from morning glory plant rubber for different products

1839 Vulcanization (Charles Goodyear) Rubber + S durable material w/ crosslinks (Car Tires)

1861 Colloidal Science is born (Thomas Graham)1907 Oldest synthetic plastic (Leo Bakeland)1917 development of x-ray crystallography1925 x-ray crystallography of cellulose proves

polymers are long structures

Brief History Con’t

1927 Large production of Vinyl Chloride begins1930 Polystyrene is invented1938 Nylon is produced for the first time

Wallace Carothers @ the Dupont Company

1940’s Natural Rubber shortage due to WWII Opens market for synthetic rubber

1940’s Work done on the kinetics of polymerization

1941 Polyethylene is developed1950’s Polymers with stereochemistry developed

Ziegler-Natta

Brief History Con’t

1970’s Engineering/Conductive Polymers developed

1970 Ekonol (moldable polymer) is developed James Economy

1971 Liquid Crystal Polymers Developed1971 Kevlar is developed

Patented by S. Kwolek among 37 polymer science patents1976 Polymers becomes the US most widely

used material 1980-Present making polymers “green”2010’s- Polymer wires

What are Polymers?

Polymers are compounds containing 1 or more repeating unit.

Unlike regular compounds polymers do not have a clearly defined molecular weight

They can be crystalline or amorphousThey are classified depending on their

starting materials (monomer)

Families of Polymers

1. Nylons2. Polyurethanes3. Polyvinyls4. Polyesters5. Polyethers/Polyalcohols6. Polycarbonates7. Phenolics8. Polyimides

Properties

Tacticity Syndiotactic, Isotactic, Atactic

Cross-linking Affects rigidity

Branching Affects crystallinity

GyrationTg

Types of Polymers

Thermoplastic Heat/cool many times

Elastomer Polymer containing “few” cross-links so it can stretch

Thermoset Polymer that can withstand heat (shapewise)

Blends Mixtures of polymers created to protect the properties

of a product

Polymerization

There are two main polymerization “reactions” Free-Radical Polymerization Condensation Polymerization

Free-radical Polymerization Requires an Initiator and a quencher Produces “living” polymers Produces “high-density” polymers High MW polymers Low polydispersity samples

Polymerization

Condensation Reactions Produces Low-Density Polymers Large polydispersity samples No initiator or quencher required Water byproduct

Polymer Uses

Polymer Use

Polyethylene Toys, containers, Saran Wrap (new)

Polypropylene Furniture, fiber, carpet

Polyvinylchloride Water pipes, floor tile

Polytetrafluoroethylene Teflon

Polyacrylic acid Adhesive & Diaper absorption

Polymethacrylic acid Thickener

Poly(methylmethacrylate) Pexiglass/Safety Glass

Recycling

Expensive Each polymer has its own recycling process There has to be “high demand” for the individual

polymer It has to be “easy” to transport

What do the Numbers mean? They tell you what the polymer used in the container

is.

#

Recycling by Numbers

#1 PETE (PolyEthylene Teraphthalate) Soda Bottles and Food Trays (high demand)

End up as carpets

#2 HDPE (High Density PolyEthylene) Milk & Water Jugs (high demand)

If “colorless” ends up as a new container If colored ends up as “lumber”

#3 “vinyl” or PVC (PolyVinylChloride) White pipes (low demand)

Recycling by Numbers Con’t

#4 LDPE (Low Density PolyEthylene) Plastic bags (high demand but “hard” to transport)

They end up as new bags or “lumber”#5 PP (PolyPropylene)

Tough food containers (yogurt, butter) Not enough “demand” to make it profitable

#6 PS (PolyStyrene) Not cost effective to recycle but still recycled

Inflated PS ends up as packaging Compacted PS ends up as CD/DVD cases and

utensils/containers#7 Other (mixture)

Can’t be recycled as the mixture can’t be separated