Polymer Science and Engineering
"I am inclined to think that the
development of polymerization
is perhaps the biggest thing that
chemistry has done, where it has
had the biggest effect on
everyday life”
—Lord Todd,1980
Ethylene
CH = CH
2
2
Polyethylene
Magic ?
[-CH -CH -]n
2
2
A Useful Classification
USE
NATURAL
SYNTHETIC
Fibers
Adhesives
Wool, Silk,
Cellulose
Natural Rubber,
Elastin
Gutta Percha,
DNA,
Polypeptides
Wood,
Bone,
Teeth
Barnacles!
Paints
Shellac
Nylon, PET,
Lycra®
SBR, Silicones,
Polybutadiene
Polyethylene,
Polypropylene,
Polystyrene
Polyester/Glass,
Carbon Fiber/Epoxy
Formica
Elmer’s “Glue-All”
Super-Glue
Acrylics
Elastomers
Plastics
Composites
Historical Background
NATURAL POLYMERS
- used throughout recorded
history
SYNTHETIC POLYMERS
- initially chemically modified
natural polymers
RUBBERS OR ELASTOMERS
- unique materials, both
natural and synthetic
Historical Background
1845
1848
1862
1870’s
1884
SCHOENBEIM
- nitration reactions
MENARD
- collodion films ;nitrated
cellulose
PARKES
- "Parkesine" ; added
camphor (and other stuff)
- plasticizers
HYATT
- billiard balls !!
CHARDONNET
- extrusion
1890’s
CROSS, BEVAN,
& BEADLE
1905
BAEKELAND
- Bakelite, the first thermoset
STAUDINGER
- the macromolecular hypothesis
1920
> 1920
NEW THERMOPLASTICS
- regenerated cellulose
rayon,cellophane
- (more on these later)
Natural Polymers
NATURAL POLYMERS - - used throughout recorded history
A natural fiber
on the hoof
Silk
Better hope your garden never looks like this
Cotton
Nitrated Cellulose
OH
HO
O
O
CH2
OH
Cellulose
Schoenbeim
n
Explosive Stuff!
O
N
O
O
C
C
C
C
O
O
C
O
Glycerol
CH2OH–CHOH–CH2OH
C
O
O
N
N
O
O
O
O
Nitroglycerin
Some Basic Chemistry:
Atoms and Bonding
H
Covalent
H
Na
Cl
H
Ionic
–
H
Cl
Molecule
+
Na
Does not form NaCl molecule!
Metallic
Some Basic Chemistry:
Single and Double Bonds
C
H–C –H
–
C
–
H
H
–
–
–
C
H H
–
C
CH4
H–C – C –H
H H
C2H6
–
–
C
–
C
–
H H
C–C
H H
C2H4
Some Basic Chemistry:
Functional Groups
CH2=CH2
Ethylene
O
O
R–C–O–R
Ester
O
=
=
R–NH2 + R–C–OH
Amine Carboxylic Acid
=
=
R–OH + R–C–OH
Alcohol Carboxylic Acid
O
R–C–NH–R
Amide
Functional Groups are small groups of atoms held together in a specific
arrangement by covalent bonds. They are responsible for the principle chemical
properties of the molecule in which they are found.
Condensation Reactions
O
Reversible
Reaction!
CH3 - C - OH + CH3 - CH2 - OH
Acetic Acid
Ethyl Alcohol
or Ethanol
O
Ester linkage
CH3 - C - O - CH2 - CH3 + H2O
Ethyl Acetate
If you don’t
know what this
is you should
be castigated
unmercifully
Why do Molecules React ?
Acetic Acid
O
CH3 - C - OH
kersplat!
HO - CH2 - CH3
Ethyl Alcohol
or Ethanol
Why do Molecules React ?
O
H:O - CH2 - CH3
CH3 - C:OH
HO. + .H
O
CH3 - C. + .O - CH2 - CH3
HO:H ~ H2O
O
CH3 - C:O - CH2 - CH3
This isn‛t what really happens, but shows you
how the valency electrons get rearranged
Making a Polymer
O
CH3 - C - OH + CH3 - CH2 - OH
Acetic Acid
Ethyl Alcohol
or Ethanol
Reversible
Reaction!
O
Ester linkage
CH3 - C - O - CH2 - CH3 + H2O
Ethyl Acetate
If we heat acetic acid and ethanol up to just over 1000C,
to get the reaction going and drive off water, why don‛t
we form polymer?
Explosive Stuff!
O
N
O
O
C
C
C
C
O
O
C
O
Glycerol
CH2OH–CHOH–CH2OH
C
O
O
N
N
O
O
O
O
Nitroglycerin
Guncotton
and
Collodion
Guncotton and
Collodion
P a r k e s and P a r k e s i n e
He wasn’t this
miserable.
The Crystal Palace
Hyatt and the Elephants
Celluloid
What a sales pitch
C h a r d o n n e t and Mother-in-Law Silk
Regenerated Cellulose
Cellophane and Rayon
OH
HO
O
O
CH 2OH
NaOH
OH
HO
O
O
CH 2ONa
CS2
OH
HO
O
O
CH 2OCSNa
H+
S
OH
HO
O
O
CH2OH
More
Cellophane
Rayon
B a e k e l a n d and Bakelite
The first true synthetic plastic
Bakelite - Material of a Thousand Uses
Clear Bakelite items
A Bakelite camera
Clock made of a phenolic resin
and celluloid
A Bakelite radio
A Bakelite telephone
A Bakelite microphone
Network Formation
The hydrogens in the ortho and para positions to
the OH group, which by convention are not
usually shown but here are indicated by a *, can
react with fomaldehyde to form (initially)
oligomers.
OH
*
OH
CH2
CH2
OH
CH2
OH
CH2
OH
OH
+ CH 2O
*
OH
CH2
*
CH2
CH2
OH
OH
A Condensation Reaction!
OH
OH
H
H
H
H
H
H
H
H
H
H
H
OH
H
H
H
H
H
H
H
O
H
O
Network Formation
Continued reaction
builds up a densely
cross-linked network.
This is Bakelite, a
thermosetting
polymer. Once the
reaction is complete,
the material cannot
be reheated and
reformed. So, what do
you think the
definition of a
thermoplastic is?
OH
CH 2
OH
CH2
OH
CH 2
OH
CH 2
CH2
OH
HO
CH 2
CH 2
CH 2
O
CH 2
OH
O
CH 2
H 2C
CH 2
CH 2
H2 C
HO
OH
CH 2
HO
HO
CH 2
HO
O
CH 2
CH 2
HO
OH
CH 2
CH 2
NEXT;
S t a u d i n g e r and the
Macromolecular
Hypothesis