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 Polyethylene C 2 = C 2 Magic? [-C 2 -C 2 -] n
A Useful Classification USE NATURAL SYNTETIC Fibers Wool, Silk, Cellulose Nylon, PET, Lycra Elastomers Natural Rubber, Elastin SBR, Silicones, Polybutadiene Plastics Gutta Percha, DNA, Polypeptides Polyethylene, Polypropylene, Polystyrene Composites Wood, Bone, Teeth Polyester/Glass, Carbon Fiber/Epoxy Formica Adhesives Barnacles! Elmer s Glue-All Super-Glue Paints Shellac Acrylics
istorical Background NATURAL PLYMERS - used throughout recorded history SYNTETIC PLYMERS - initially chemically modified natural polymers RUBBERS R ELASTMERS - unique materials, both natural and synthetic
istorical Background 1845 1848 1862 1870 s 1884 1890 s 1905 1920 > 1920 SCENBEIM - nitration reactions MENARD - collodion films ;nitrated cellulose PARKES - "Parkesine" ; added camphor (and other stuff) - plasticizers YATT - billiard balls!! CARDNNET - extrusion CRSS, BEVAN, - regenerated cellulose & BEADLE rayon,cellophane BAEKELAND - Bakelite, the first thermoset STAUDINGER - the macromolecular hypothesis NEW TERMPLASTICS - (more on these later)
Natural Polymers NATURAL PLYMERS - - used throughout recorded history A natural fiber on the hoof Silk
Better hope your garden never looks like this
Cotton
Nitrated Cellulose C 2 Cellulose n Schoenbeim
Explosive Stuff! C C C C C N C Glycerol C 2 C C 2 N N Nitroglycerin
Some Basic Chemistry: Atoms and Bonding Cl Na Covalent Ionic Cl + Na Molecule Metallic Does not form NaCl molecule!
Some Basic Chemistry: Single and Double Bonds C C C C 4 C C C C C 2 6 C C C C C 2 4
Some Basic Chemistry: Functional Groups = C 2 =C 2 Ethylene = R + R C R C R Alcohol Carboxylic Acid Ester R N 2 Amine = + R C Carboxylic Acid = R C N 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 Acetic Acid Ethyl Alcohol or Ethanol Reversible Reaction! Ethyl Acetate Ester linkage C 3 - C - + C 3 - C 2 - C 3 - C - - C 2 - C 3 + 2 If you don t know what this is you should be castigated unmercifully
Why do Molecules React? Acetic Acid C 3 - C - kersplat! - C 2 - C 3 Ethyl Alcohol or Ethanol
Why do Molecules React? C 3 - C: : - C 2 - C 3. +. : ~ 2 C 3 - C. +. - C 2 - C 3 C 3 - C: - C 2 - C 3 This isn t what really happens, but shows you how the valency electrons get rearranged
Making a Polymer Acetic Acid Ethyl Alcohol or Ethanol Reversible Reaction! Ethyl Acetate Ester linkage C 3 - C - + C 3 - C 2 - C 3 - C - - C 2 - C 3 + 2 If we heat acetic acid and ethanol up to just over 100 0 C, to get the reaction going and drive off water, why don t we form polymer?
Explosive Stuff! C C C C C N C Glycerol C 2 C C 2 N N Nitroglycerin
Guncotton and Collodion
Guncotton and Collodion
Parkes and Parkesine e wasn t this miserable.
The Crystal Palace
yatt and the Elephants
Celluloid What a sales pitch
Chardonnet and Mother-in-Law Silk
Regenerated Cellulose Cellophane and Rayon C 2 Na C 2 Na CS 2 C 2 CSNa + S C 2
More Cellophane
Rayon
Baekeland and Bakelite The first true synthetic plastic
Bakelite - Material of a Thousand Uses Clear Bakelite items Clock made of a phenolic resin and celluloid A Bakelite telephone A Bakelite camera A Bakelite radio A Bakelite microphone
Network Formation The hydrogens in the ortho and para positions to the group, which by convention are not usually shown but here are indicated by a *, can react with fomaldehyde to form (initially) oligomers. * * * + C2 C 2 C 2 C 2 C 2 C 2 C 2 C 2
A Condensation Reaction!
Network Formation Continued reaction builds up a densely cross-linked network. This is Bakelite, a thermosetting polymer. nce the reaction is complete, the material cannot be reheated and reformed. So, what do you think the definition of a thermoplastic is? C 2 C 2 C 2 2 C 2 C C 2 C 2 C 2 C 2 C 2 C 2 C 2 C 2 C 2 C 2 C 2 C 2 C 2 C 2 C 2
NEXT; Staudinger and the Macromolecular ypothesis