INTRODUCTION TO POLYMERS AND PLASTICS

ADDITION POLYMERS OF ALKENES

“polymer” – Greek word “polys” = many and “meros” =

parts

Polymers – macromolecules composed of repeating structural units called monomers

GENERAL REACTION

R

R

R

R

C C

RR

C C

RR

R

R

R

R

C C C

R

R

R

R

R

RAlkene monomer

heat

pressure

Addition polymer

EXAMPLES OF ADDITION POLYMERS

CH2

CH2 n

nCH2=CH2

Ethene (ethylene) Polyethylene

CH2

CH

nnCH2=CH2

Propene (propylene) Polypropylene

CH3 CH3

YOU TRY!

Draw the polymer that would be made from the monomer vinyl chloride. What would it be called?

H2C CH

Cl

H2C CH

Cl

+

ANOTHER PRACTICE PROBLEM

Draw the polymer that would be made from the monomer styrene. What would it be called?H2C CH H2C CH+

COPOLYMERS

When two different monomers are combined by addition polymerization, a copolymer is formed. The polymer is random.

-E-P-P-E-E-E-P-P-E-P-E-E-E-P-P-P-E-P-

H2C CH2 H2C CH+

CH3

H2C

H2C

HC

CH2

H2C

CONDENSATION REACTIONS

Another method of making polymers Two compounds are combined One compound will lose a H atom and

the other will lose an –OH group. These combine to form water. Nylons and polyesters are formed by

condensation polymerization. They form in an alternating pattern.

PRODUCTION OF NYLON 66

CCH2CH2CH2CH2C

O

HO

O

OH + H NCH2CH2CH2CH2CH2CH2N

H H

H

CCH2CH2CH2CH2C

O

HOO

NCH2CH2CH2CH2CH2CH2N

H H

H + H2O

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NATURAL VS SYNTHETIC POLYMERS The most abundant organic molecules

in the world are polymers Examples of Natural Polymers:

1. cellulose & lignan (main fibers in wood) 2. starch (stored sugar in plants) 3. chitin (fiber in the cell walls of algae,

fungi and arthropods) 4. collagen 5. DNA, RNA, and protein 6. cotton, wool, silk and flax

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PLASTICS Plastics are a group of materials

manufactured primarily from petroleum and natural gas.

All plastics are polymers. Plastics are distinguished by their ability to

be easily formed and molded in many ways for many purposes

1907 – 1st fully synthetic polymer “Bakelite” Hard plastic used as an electrical insulator Paved the way for the >60,000 plastics

made today

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USES OF POLYMERS

POLYMER PROPERTIES APPLICATIONS

Neoprene Chemical resistant, rubbery

Shoe soles, radiator hoses

Polyamide (nylon)

Fibrous, strong, durable

Parachutes, carpet, hosiery

polyester Fibers recover quickly after extension, moisture resistant

Filters, insulation, tire cords, Dacron, Mylar

Polyurethane Flexible foams, elastic quick-drying fibers, hard-drying films

Mattresses,Airplane wings,Spandex, Lycra,varnishes

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USES OF POLYMERSPOLYMER PROPERTIES APPLICATIONS

Polyvinyl alcohol Colorless, water-soluble, flammable resin

Adhesives, lacquers, coatings & films

Polyvinyl chloride -Rigid when unplasticized, // flexible when placticized

Pipes, records, floor tiles, credit cards //Raincoats, shower curtains

Polyvinyl fluoride Resistant to chemicals and weathering

Protective films for siding, pipes, chemical containers

Polyvinylacetate Water-insoluble resin

Carpet backing, latex paint, adhesive & cement

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RECYCLING PLASTIC POLYMERS

Between 1960 and 2000, the total annual solid waste in the US doubled from 80 million tons to 160 million tons

About 20% of the volume of trash is composed of plastics

Plastics, unlike paper and garden debris, are not biodegradable

Coding system identifies types of plastics so they can be categorized for recycling purposes

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RECYCLING PLASTIC POLYMERS

All plastics with the same recycling code are made of the same polymer

The letters under the code symbol tell you from what plastic it is made

Recyclers use the codes to separate plastics into groups

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RECYCLING PLASTIC POLYMERS INVESTIGATION

Each lab station has examples of the first 6 recycling codes.

Begin at your usual lab station. Then rotate through all stations, 1 - 6

Complete the chart for each recycling code. *Describe the plastics: are they clear, rigid, crinkly, glossy, etc

*Name some of the sample products: pop bottles, milk jugs, grocery bags, etc.

BE SURE TO NOTE THE SIMILARITIES AND DIFFERENCES AMONG THE DIFFERENT

POLYMERS

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PLASTIC RECYCLING CODESRECYCLING CODE

POLYMER RESIN

DESCRIPTION SAMPLE PRODUCTS

PolyethyleneTerephthalate(PET or PETE)

Usually clear or green; rigid

Peanut butter jars, salad dressing & soft drink bottles

High-density Polyethylene(HDPE)

Semi-gloss, crinkly; may be hard when thick

toys; detergent, motor oil & milk containersPlastic bags

Polyvinyl chloride or vinyl (PVC-V)

Semi-rigid, glossy

Shampoo, vegetable oil bottles

Low-density polyethylene (LDPE)

Flexible, not crinkly

Grocery, bread & garment bags; shrink-wrap

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PLASTIC RECYCLING CODESRECYCLING CODE

POLYMER RESIN

DESCRIPTION SAMPLE PRODUCTS

Polypropylene

(PP)

Semi-rigid,Low gloss

Yogurt & margarine containers, bottle tops, medicine bottle

Polystyrene(PS)

Often brittle, glossy

Coffee cups, meat trays & fast food containers, CD cases

Multi-layer plastics

Squeezable Squeezable ketchup & syrup containers

LecturePLUS Timberlake

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RECYCLING PLASTICS

From Water Bottles to Polyester http://www.youtube.com/watch?v=zyF9

MxlcItw&feature=related

WHAT DETERMINES THE PROPERTIES OF A POLYMER?

STRUCTURE determines the properties and functions of a polymer

Stronger attractive forces between chains = stronger, less flexible polymer.

Chains able to slide past each other = flexible polymer

In polyethylene, attractive forces are weak induced dipole - dipole, will it be flexible or not?

Nylon has strong hydrogen bonds, why does this make it a strong fiber?

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STRUCTURE OF POLYMERS

Polymers can be created with all different degrees of hardness, flexibility, strength, and other properties by controlling structural factors such as:

BranchingCross-linking

Size (molecular mass)

POLYMER CHAIN STRUCTURES

LINEAR Monomer units are linked in a chain-like

manner (like a paper clip chain)

Examples: HDPE – high density polyethylene Polytetrafluoroethylene – Teflon PP – polypropylene

Random coil – all tangled up like a plate of spaghetti

POLYMER CHAIN STRUCTURES

BRANCHED

Has short chains attached to the main chain

Tends to have less strength and lower solution viscosity compared to a linear polymer

Examples: Polyethylene Glycogen

POLYMER CHAIN STRUCTURES

CROSS-LINKED

Caused by intermolecular forces like hydrogen bonding, covalent bonds between carbon atoms, or by disulfide bridges (bonds between sulfurs)

Examples: Vulcanized rubber Curly hair – amino acids methionine and

cysteine

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THERMOPLASTIC

80% of thermoplastic polymers are linear or branched polymers

Weak attractive forces between chains broken by warming

Change shape - can be remolded Weak forces reform in new shape when

cooled

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THERMOSET

Extensive cross-linking formed by covalent bonds.

Bonds prevent chains moving relative to each other.

What will the properties of this type of plastic be like?

LecturePLUS Timberlake

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POLYMER BUILDING

Using different colored paperclips, go back to the lab tables and build:

an addition polymera copolymera condensation polymera linear polymera branched polymera cross-linked polymer