Chapter 14 Flashcards
Most polymers are considered _____. Which consist of what elements?
Hydrocarbons
Hydrogen and Carbon
Ref: Lecture Notes CH14
What is the principal characteristic of saturated hydrocarbons?
Only single bonds are present.
Ref: Lecture Notes CH14
In saturated hydrocarbons, each carbon has only ___ valence electrons.
Four
Ref: Lecture Notes CH14
In saturated hydrocarbons, carbon’s four valence electrons are ___ bonded to the four other atoms.
Singly bonded
Ref: Lecture Notes CH14
What defines the bonding angles in saturated hydrocarbons?
Covalent Bonds.
Ref: Lecture Notes CH14
What is the simplest hydrocarbon?
Methane, CH4
Ref: Lecture Notes CH14
With respect to hydrocarbons; if the number of carbon atoms goes up, the boiling point _____.
Increases.
Ref: Lecture Notes CH14
Unsaturated hydrocarbons are chemically ____.
Reactive.
Ref: Lecture Notes CH14
Hydrocarbons that have double or triple bonds are referred to as ____.
Unsaturated hydrocarbons.
Ref: Lecture Notes CH14
In saturated vs. unsaturated hydrocarbons, which is the more reactive chemically?
Unsaturated Hydrocarbons
Ref: Lecture Notes CH14
Rank the following in terms of modulus of elasticity with highest at number one and lowest at number 3:
- Elastomer
- brittle polymer
- plastic
- Brittle polymer
- Plastic
- Elastomer
Ref: Lecture Notes CH14
Define Isomerism.
Two compounds with the same chemical formula that have quite different physical structures.
Ref: Lecture Notes CH14
Typically isomerism belongs to _____ molecular chains.
Longer
Ref: Lecture Notes CH14
What product is polyethylene (PE) used in?
Tupperware and other common household plastics. Packaging, grocery bags, children’s toys.
Ref: Wikipedia
What product is poly-vinyl chloride (PVC) used in?
It’s a common use, very versatile plastic.
My experience: Tubing and plumbing
Ref: Wikipedia
What general applications is Polytetrafluoroethylene (PTFE) used in?
Teflon Tape, chemically inert pipes, anti-corrosion applications.
Ref: Wikipedia
What is Polypropylene (PP) used in?
Common household plastics and packaging.
Ref: Wikipediaa
What is polystyrene (PS) generally used for?
PS is a hard solid plastic so it can be used in household appliances to gardening (pots and tools) to cups and firmware.
Ref: Wikipedia
The extent of polymerization will determine the ___.
Molecular weight.
Ref: Lecture Notes CH14
What is the key characteristic of polymeric materials?
Molecular weight
Ref: Lecture Notes CH14
If the polymer chain length is increased, what corresponding change in properties will take place?
- Increased melting point.
- Increased viscosity
- Increased impact resistance
- Increased strength and toughness
“My Very Independent Idiot.”
Ref: Lecture Notes CH14
Give some reason why increasing chain length gives desirable property changes.
- Increase in chain interactions (van der Waals forces) as the density of entanglements increases.
- The presence of number one results in stronger bonding which enables resistance against deformation.
Ref: Lecture Notes CH14
What is the “Degree of polymerization?”
The average number of repeat units per chain.
Ref: Lecture Notes CH14
What are the four main molecular structures for polymers?
Linear
Branched
Cross-Linked
Network
“Lary Bought Cable News.”
Ref: Lecture Notes CH14
What is “tacticity?”
Stereoregularity or the spatial arrangement of free radical units (R) along a chain.
Ref: Lecture Notes CH14
In an isotactic configuration, all R groups are on ____.
The same side of the chain.
Ref: Lecture Notes CH14
In a syndiotactic configuration, all R groups are on ____.
Alternate sides of the chain.
Ref: Lecture Notes CH14
In an atactic configuration, all R groups are on ____.
Radom sides of the chain.
Ref: Lecture Notes CH14
What is the difference between cis and trans isomerism?
cis- side groups are on the same side of the chain
trans - side groups are on opposite sides of the chain.
Ref: Lecture Notes CH14
What is a copolymer?
Two or more monomers are polymerized together on the same chain.
Ref: Lecture Notes CH14
What are the four types of copolymers?
- Random
- Alternating
- Block
- Graft
Randy Ate Big Gators.
Ref: Lecture Notes CH14
Why are polymers rarely 100% crystalline?
It’s extremely difficult for all regions of all chains to become aligned in the same configuration to form crystals.
Ref: Lecture Notes CH14
What are the three main families of Polymers?
- Thermoplastics
- Thermosets (resins)
- Elastomers.
Ref: Lecture Notes CH14
True or False
Thermoplastics can be amorphous or crystalline?
True
Ref: Lecture Notes CH14
Thermoplastics can be softened when ____, and hardened when ____.
Heated
Cooled
Ref: Lecture Notes CH14
True or False
Thermoplastics have low strength but are ductile compared to Thermosets.
True
Ref: Lecture Notes CH14
True or False
Thermosets are NEVER amorphous.
False, they are always amorphous.
Ref: Lecture Notes CH14
True or False
Thermosets are generally strong and rigid but often brittle.
True
Ref: Lecture Notes CH14
True or False
The process of heating to soften and cooling to harden Thermoplastics can be extended to thermosets.
False, thermosets are crosslinked structures. Once curred the process cannot be reversed.
Ref: Lecture Notes CH14
True or False
Elastomers are amorphous in all states.
True
Ref: Lecture Notes CH14
What is the primary difference between elastomers and thermoset/thermoplastics?
Their unique ability to elastically deform by extremely large amounts relative to their undeformed length without any permanent deformation.
An example would be a rubber band.
Ref: Lecture Notes CH14
