Chapter 14 (Polymers)
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What are plastics and Elastomers made from?
polymeric materials
what are the benefits of COMMERCIAL polymers (3)?
• lightweight • corrosion-resistant • good maleability
what are the benefits of ENGINEERING polymers? (3)
• improved strength - better properties at high temps
what are most polymers made of?
hydrocarbons (H&C)
what is a saturated carbon?
a carbon bonded to 4 other atoms
what can be said about double and triple bonds?
they are reactive and likely to form new bonds
Name a double bond and describe the carbon configuration
Ethylene or ethene. Each C has 4 bonds, but only 3 atoms bound to it due to the double bond
name a triple bond and describe the carbon configuration
acetylene or ethyne. Each carbon has 4 bonds but only 2 atoms bonded to it due to the triple bond
How many and what type of bond does a carbon molecule want to form
4 covalent bonds
If a double or triple bond is formed, what kind of molecules do we have?
unsaturated hydrocarbon molecules
how are other groups formed (excluding H)
by arranging varying proportions of hydrocarbons and end groups
what are “mers” (monomers)
the basic building unit. These are combined to form a polymer
What is Isomerism, and give an example
when 2 compound with the same chemical formula can have different structures, ex: C8H18 can make n-ocatne and isooctane
what is the process of the joining of monomers to form polymers
polymerization
What is the polymer of the ethene monomer?
Polyethylene
What is the molar mass?
the mass of one mole of polymer chains
If a chain is made up of 10000 repeat units and the molar mass is 30, then what is the relative molecular mass
10000 * 30=300,000 g/mol
what is the molecular weight?
the mass of a mole of chains, the longer the chain, the greater the weight
what is the relationship between Tensile strength and Molecular Weight
As Molecular weight increases, so does Tensile strength. Because the longer chains are generally more entangled therefore stronger
What is the percent crystallinity?
the percent of a material that is crystalline
As % crystallinity increase what also increases?
Tensile strength and E(yungs)
If we want to increase the %crystallinity, what process can we use?
annealing.
what is the degree of polymerization?
the average number of repeat units per chain
Which types of bonds/side groups restrict rotation
double bonds restrict rotation and bulky side groups as well