1. Definition: A molecule that is made of repeating structural units. Each individual unit is known as a monomer.

4. NaturalSynthetic Found in nature  Cellulose  Starch  Nucleic Acids (DNA)  Proteins Man Made polymers  Plastics (polyethylene)  PVC  Styrofoam  Nylon  Rubber

6.  Petroleum is the natural resource that is used to make several common synthetic polymers, such as polyethylene.  Petroleum is a dark black liquid that is a mixture of organic compounds.

8.  Plastic – Bendable, but does not return to original shape  Plastomer – bendable polymers  Elastic – Bendable, but does return to original shape  Elastomers – Elastic polymers  Brittle – Not flexible. Will break, not bend

9.  Polymers that are bonded in straight lines  Generally high Melting Point  High Density

10.  Monomers branch off a polymer structure  Low Density because they occupy more space

11.  Linear polymers are linked together  Hard, brittle, not flexible  More cross-links = increase strength and stiffness

12. 1) Chains tangle  Think of shrink wrapping on DVD’s  Polymer shrinks as chains tangle 2) Chains untangle  Think of stretching some hot plastics  Polymers are able to be stretched and untangled

13. When polymer chain (or chains) get tangled  Think of a tangled ball of string  Cold pile of spaghetti More entangled = stronger and less flexible

14.  The ethylene molecule is manipulated in different chain structures to give the plastic certain physical properties.  The base hydrocarbon is substituted with other atoms (ex, chlorine in PVC) to create new plastics with different physical properties.