Plastics

For now this is going to be mostly focused on Nylon

Nylon

• Started as a Dupont brand name for a specific polymer.
• Now describes all aliphatic polyamides (Def: repeating units of amide bonds)

Nylon 6,6

• Repeating units of $\text{ce}–[NH–(C{H}_2{)}_6–NH–CO–(C{H}_2{)}_4–CO]–$
• the 6’s refer to the carbon count along each of the two segments in a monomer

• Uses & Properties
  • Stiffer, harder, higher MP than other Nylons
  • Makes it suitable for rough applications like break pads, carpet, auto parts, power tools.
  • 1/3rd is woven, 2/3 is injection molded
• Synthesis

  • Transclude of nylon-synthesis.avif

  • Nylon 6,6
    • Same process globally
    • $Part1:\text{ce}HMD+AA->nylonsalt:[H3N^{+}-(CH2)6-NH{3}^{+}]{[}^{-}OOC-(CH2)4-CO{O}^{-}]$
    • $Part2:\text{ce}condensationundervacuumat270C$
    • Cool, pelletize, spin, do whatever
  • HMD - Hexaethylenediamine
    • Same general process globally, but people make custom catalysts
    • $\text{ce}NC-(CH2)4-CN+4H2->[Ni,RaneyNi]H2N-(CH2)6-NH2$
    • 100 - 150 C and 30 - 50 atm, then filtered/stripped/distilled
    • Parasitic: cyclization or overreduction of ADN
  • ADN - Adiponitrile
    • Produced via proprietary electrohydrodimerization process.
    • $\text{ce}4CH2=CH-CN+2H2O->2NC-(CH2)4-CN+O2$ (this is total reaction, not half)
    • Pulse voltage in a heavy metal CSTR at mild conditions, $\gamma =0.80$
    • Parasitic: hydrogen evolution (dangerous but inexpensive) and AN reduction (not dangerous but costly)
  • AN - Acrylonitrile
    • Accessible industrial process, catalytic ammoxidation
    • $\text{ce}C3H6+NH3+1.5O2->[BiMo]C3H3N+3H2O$
    • 400 - 500 C and 1 - 3 atm, purified via distillation