Polymers Polymers Hair Hair Fur Fur Fingernails Fingernails Silk Silk Cotton Cotton Polyamides(nylons) Polyamides(nylons) Polyester Polyester Polyethylene Polyethylene PVA PVA PVC PVC Dacron Dacron Lycra Lycra What are they all?
Jan 01, 2016
PolymersPolymersHairHair
FurFur
FingernailsFingernails
SilkSilk
CottonCotton
Polyamides(nylons)Polyamides(nylons)
PolyesterPolyester
PolyethylenePolyethylene
PVAPVA
PVCPVC
DacronDacron
LycraLycraWhat are they all?
PolymersPolymers
The word polymerThe word polymer literally literally means "many parts.” means "many parts.”
repeating structural units repeating structural units called monomers.called monomers.
There are both naturally There are both naturally occurring and synthetic occurring and synthetic polymers.polymers.
MerMerMer – Mer –
The repeating unit in a polymer chainThe repeating unit in a polymer chain
Monomer –Monomer – A single mer unit (n=1)A single mer unit (n=1)
Polymer –Polymer – Many mer-units along a chain (n=10Many mer-units along a chain (n=1033 or more) or more)
Degree of Polymerization –Degree of Polymerization –
The average number of mer-units in a The average number of mer-units in a chain. chain.
There are both naturally There are both naturally occurring and synthetic occurring and synthetic
polymers.polymers.
Naturally Naturally occurring occurring polymerspolymers
proteinsproteinsStarchesStarches cellulose cellulose (plants)(plants)Rubber/latex.Rubber/latex.RNA/DNARNA/DNAcarbohydratescarbohydrates
SyntheticSyntheticPolyethylenePolyethylenePolyvinyl chloridePolyvinyl chloridePolystyrenePolystyrene
Plastics are Plastics are synthetic synthetic polymerspolymers
Synthetic Synthetic polymers remain polymers remain in the environment in the environment for a LONG TIMEfor a LONG TIME
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Different Polymer Different Polymer StructuresStructures
Important Important VocabularyVocabulary
PlastomerPlastomer – bendable polymers – bendable polymers
ElastomersElastomers – Elastic polymers – Elastic polymers
Brittle – Not flexible. Will break, not Brittle – Not flexible. Will break, not bendbend
PolymersPolymersA polymer is a long chain of molecules A polymer is a long chain of molecules that look something like strands of that look something like strands of cooked spaghetti. cooked spaghetti.
If the polymer chains slide past each If the polymer chains slide past each other easily, then the substance acts other easily, then the substance acts like a liquid, because the molecules like a liquid, because the molecules flow.flow.
If the molecules hook together at a If the molecules hook together at a few places along the strand, then the few places along the strand, then the substance behaves like a rubbery substance behaves like a rubbery solid.solid.
Linear Polymer Linear Polymer Structure Structure
Polymers that are bonded Polymers that are bonded in straight lines, form long in straight lines, form long chains or cross-linked chains or cross-linked structures.structures.
Generally high Melting PointGenerally high Melting Pointthermoplasticsthermoplastics
High Density High Density
Strength Depends Strength Depends on Directionon Direction
Tape Experiment Tape Experiment
1.1. Tear tape acrossTear tape across
2.2. Tear tape lengthwiseTear tape lengthwise
Do they tear the same? Why? Do they tear the same? Why?
Branched Branched Structure Structure Monomers branch off a polymer Monomers branch off a polymer
structurestructure
Low Density because they Low Density because they occupy more space occupy more space
Why do Low Density polymers have Why do Low Density polymers have more branches? more branches?
Fewer branches allow the carbon Fewer branches allow the carbon backbones to get close togetherbackbones to get close together
More Branches =More Branches = Fewer Fewer Branches = Branches =
less mass in spaceless mass in space more more mass in spacemass in space
Cross-Linked Cross-Linked Polymer Polymer
Linear polymers are linked Linear polymers are linked together together
Either covalent or hydrogen Either covalent or hydrogen bondsbonds
Hard, brittle, not flexible Hard, brittle, not flexible More cross-links = increase More cross-links = increase strength and stiffnessstrength and stiffness
Entanglement Entanglement When polymer chain (or chains) When polymer chain (or chains)
get tangled get tangled Think of a tangled ball of Think of a tangled ball of stringstringCold pile of spaghetti Cold pile of spaghetti
More entangled = stronger and More entangled = stronger and less flexible less flexible
Review Review To increase To increase StrengthStrength
Increase # of cross-linksIncrease # of cross-linksLots of entanglementsLots of entanglements
To increase To increase DensityDensity Decrease # of branched Decrease # of branched Make linear structures, not branchedMake linear structures, not branched
To increase To increase Flexibility Flexibility Decrease # of branched Decrease # of branched Make linear structures, not branchedMake linear structures, not branchedIncrease temperature Increase temperature
What is going on?What is going on?CROSS – LINKING CROSS – LINKING
Borax is helping PVAs ionically bond Borax is helping PVAs ionically bond togethertogether
Test your Test your knowledgeknowledge
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