Definition: A molecule that is made of repeating structural units. Each individual unit is known as a monomer.
NaturalSynthetic Found in nature Cellulose Starch Nucleic Acids (DNA) Proteins Man Made polymers Plastics (polyethylene) PVC Styrofoam Nylon Rubber
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.
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
Polymers that are bonded in straight lines Generally high Melting Point High Density
Monomers branch off a polymer structure Low Density because they occupy more space
Linear polymers are linked together Hard, brittle, not flexible More cross-links = increase strength and stiffness
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
When polymer chain (or chains) get tangled Think of a tangled ball of string Cold pile of spaghetti More entangled = stronger and less flexible
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.