A monomer is a molecule that is able to bond in long chains. A polymer can be made up of monomer linked together. Linking up of monomers is called polymerization.

A monomer is a molecule that is able to bond in long chains.A polymer can be made up of monomer linked together.Linking up of monomers is called polymerization.A copolymer is made up of two or more types of monomers.

POLYMERSManufacturing process to make

Condensation polymerisation

• Condensation polymers are formed by the ‘head-to-tail’ joining of monomer accompanied by the loss of a small molecule such as water. The reaction requires the presence of two reactive functional groups on each monomer undergoing the reaction.

Addition polymerisation

• For addition polymerisation to occur, the monomer must have a double bond between two carbon atoms. This double bond breaks to allow the long chains to form.

These are the carbon atoms with their double-bond (2 shared electrons each). A collision breaks the double bond.

Once the double bond is broken, a chain reaction will occur between monomers. In about a second an entire chamber of compressed ethylene gas turns into the polymer, polyethylene.

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Ethylene has two carbons; plus, instead of the two carbons sharing just one electron each, they share two electrons each. High temperature or UV light can cause two of these shared (paired) electrons to become unshared (unpaired).

These unpaired electrons are eager to pair up with another electron. If this ethylene molecule bumps another ethylene molecule, the unpaired electrons will cause the one it bumped into to lend one of its inner electrons.

Molecular Structure of Polymers

Linear-the main backbone is unbranched Eg. High Density Polyethylene (HDPE), PVC, Nylon,

Cotton Branched-the main backbone is branched.

Eg.Low Density Polymer Cross-linked:a small amount of cross-linking (i.e. covalent bonding) between the chains creates an elastomer Eg.Rubber NetworkWhen a large amount of cross-linking is introduced,a rigid polymer results(thermosetting plastics)

Eg. Bakelite, Kevlar, Epoxy

High density and low density• If the chains can pack closely together, the dispersion forces

between them can act more effectively. Such polymers are usually higher in density and hence tougher and harder than polymers where the chains cannot get as close together.

• When side branches are arranged on the same side of a linear polymer, the polymer is isotactic. Due to the greater effect of dispersion forces, such polymers can pack together closely, producing a substance which has a high density and is rigid.

• When the branches occur at irregular points on both sides of the chain of a linear polymer, the polymer is atactic. In these polymers the chains of molecules cannot get as close together and a low density substance is formed.

Low-Density Polyethylene (LDPE)

Because the attraction becomesweaker as the chains are further apart, the density of the resultant compound is low and LDPE is soft, flexible and translucent

High-Density Polyethylene (HDPE)

Chain Length: 10,000 – 100,000

Polymer

• There are two types of polymers: synthetic and natural.• Synthetic polymers are derived from petroleum oil, and

made by scientists and engineers. • Examples: nylon, polyethylene, polyester, Teflon, and

epoxy.• Natural polymers occur in nature and are often water-

based. • Examples: rubber,silk, wool, DNA, cellulose and

proteins.

Cotton fiber is mostly cellulose, and cellulose is made of chains of the sugar, glucose linked together a certain way.

Rubber Tree

Sap: Sticky Viscous Gooey

Vulcanization

Heating natural rubber with varying amount of sulphur. The sulphur creates cross link between chains and make it more elastic and durable.

Sulphur cross link in rubber .

Nylon was discovered in 1935. The name nylon is Nylon was discovered in 1935. The name nylon is derived from two cities where it was discovered namely derived from two cities where it was discovered namely New York (NY) and London (LON). New York (NY) and London (LON).

Nylon is used in clothes, shoes, jackets, belts, and accessories. It’s not surprising a magazine is named after this polymer. Where did nylon get its name?

Polyester is a another

copolymer. Polyester is

used to make bottles and

fabrics.

A polymer made form just one

monomer is polyethylene. It

is the most common plastic

you see.

It is used for bottles, buckets, jugs, containers,

toys, even synthetic

lumber, and many other

things.

There are two types of polyethylene polymers (plastics).

high density polyethylene (HDPE);

low density polyethylene (LDPE).

One is when the polyethylene exists as long straight chains. This is called high density polyethylene (HDPE).

low density polyethylene (LDPE).

It is made by causing the long chains of ethylene to branch. That way they cannot lie next each other, which reduces the density and strength of the polyethylene. This makes the plastic lighter and more flexible.

Low density polyethylene is used to make plastic bags, plastic wrap, and squeeze bottles, plus many other things.

Another polymer, which is almost the same as polyethylene, is PolyVinyl Chloride or PVC. The difference is that every other hydrogen is replaced with a chlorine atom (green sphere).

There are many types of plastics. By controlling the length and the branching, you can control the final hardness or flexibility of the polymer plus qualities like resistance to solvents, acids, or heat.

The favorite properties of plastics are that they are inert and won't react with what is stored in them. They also are durable and won't easily decay, dissolve, or break apart. These are great qualities for things you keep, but when you throw them away, they won't decompose.

Since they don’t decompose, the answer is to recycle the plastics so they can be remade into something else.

The decks, fence, stepping stones, house shingles, and the sweat shirt, were all made from recycled plastic.

The mile long boardwalk at Yellowstone National Park was made from recycled plastic.