Plastics We use this matter resource in so many ways—but most people know very little about them.

What are most plastics used today made from? Electricity Coal Trees Rocks Petroleum Bacterial excretions

What are most plastics used today made from? 5) Petroleum But Natural Gas is also commonly used

True or False: People commonly wear clothes (shirts, jackets, etc.) that are mostly made out of plastic. 1) True 2) False

TRUE Polyester & Nylon are two examples of fibers that are actually plastics. Check your clothing tags to see if you are currently wearing plastic.

What two elements are the main components of petroleum (and thus plastics too)? Hydrogen & Oxygen Carbon & Hydrogen Carbon & Oxygen Sulfur & Oxygen Carbon & Sulfur Sulfur & Hydrogen

What two elements are the main components of petroleum? 2) Carbon & Hydrogen (Oil is often referred to as a Hydro-carbon)

ALL PLASTICS ARE MOLECULES CALLED POLYMERS What is a polymer? Many mer = Units So, a polymer is a large molecule composed of many repeating sub-units (called monomers)

Example: Monomer = CH2 Polymer = -CH2- CH2-CH2- CH2-CH2- CH2-CH- etc. Plastic = Polyethylene

WHY WOULD IT BOND AS CH2? Draw a carbon atom: + 6 6 N How many more electrons does carbon need to have a complete outer shell?

Needs 4 more—two from hydrogen… + 6 6 N + 1 + 1 + 6 6 N + 1 Covalent bonds + 6 6 N Covalent bonds + 1 and two from 2 other CH2 monomers (1 on each side).

How can you tell if a plastic bottle is polyethylene? It has a #1 in the recycling symbol. It is commonly used to make disposable bottles for water and soda. It can also be turned into fibers and made into clothing. This is called ‘polyester’.

You can manipulate plastics to take on different characteristics. Example: Adding certain chemicals when forming the polymer from heated petroleum can cause it to form in very straight chains which pack closely together.

What would happen to the density of the plastic if you make it this way? It would be more dense It would be less dense The density will not change

The plastic is more dense if the molecules pack closely together This type of plastic has its own recycling symbol… High Density Polyethylene Used commonly to make milk jugs & detergent containers The higher density gives the molecule more strength

You can also make the polyethylene molecule branch out. This LOWERS its density—so it is called… Low Density Polyethylene (LDPE) This makes the plastic more flexible. LDPE is often used in bags, wraps, and lids

The picture below shows the molecular arrangements for two types of Polyethylene. ‘A’ is #4 (LDPE) while ‘B’ is #2 (HDPE) ‘B’ is #4 (LDPE) while ‘A’ is #2 (HDPE) A B

How many different plastic recycling numbers are there? 1) Four 2) Seven 3) Twelve 4) More than Fifty

There are only 7 recycling codes…. But number 7 is ‘other’ which contains MANY different types of plastics.

Polyvinyl chloride (PVC) –(CH2CHCl)- *The addition of Chlorine atoms makes it more resistant to oils, and a lower permeability to most gases. COMMONLY USED AS… Drain pipes, Vinyl siding, etc. Source = http://www.elmhurst.edu/~chm/onlcourse/chm110/outlines/topic5.html

#5--Polypropylene Common Uses: Packaging, labeling, textiles, reusable containers & loudspeakers.

COMMONLY USED AS… Styrofoam packaging material (when injected with gases), compact disk cases, etc. Source = http://www.elmhurst.edu/~chm/onlcourse/chm110/outlines/topic5.html

These plastic types have slightly different chemical compositions or molecular arrangements --This makes the different types of plastics have slightly different properties which can be useful for different purposes. --Today’s lab will have you investigate 4 common types of plastics in order to get to know their characteristics. It will also allow us to figure out ‘unknown’ samples of plastic.