﻿152 
  ANNUAL 
  REPORT 
  SMITHSONIAN 
  INSTITUTION, 
  1943 
  

  

  parachutes 
  and 
  shroud 
  lines, 
  high-tenacity 
  rayon 
  bomb 
  chutes, 
  

   "Bubblfil" 
  life 
  preservers, 
  Vinyon 
  screen 
  printing 
  cloths, 
  nylon 
  tooth 
  

   brushes, 
  rayon 
  paint 
  brushes, 
  and 
  Velon 
  or 
  plastic-coated 
  window 
  

   screens 
  % 
  

  

  These 
  certainly 
  are 
  not 
  laboratory 
  or 
  experimental 
  ghosts 
  or 
  guinea 
  

   pigs; 
  they 
  are 
  absolute 
  realities 
  and 
  accomplished 
  facts! 
  A 
  fine 
  

   tribute 
  to 
  American 
  ingenuity 
  and 
  the 
  product 
  of 
  arduous 
  and 
  per- 
  

   sistent 
  research 
  by 
  American 
  chemists, 
  chemical 
  engineers, 
  and 
  tech- 
  

   nologists. 
  

  

  Time 
  and 
  space 
  limitations 
  preclude 
  the 
  inclusion 
  in 
  this 
  paper 
  of 
  

   many 
  technical 
  details, 
  and 
  only 
  the 
  most 
  important 
  and 
  outstanding 
  

   advances 
  in 
  new 
  synthetic 
  fibers 
  can 
  be 
  given. 
  Only 
  those 
  fibers 
  

   that 
  have 
  gone 
  beyond 
  the 
  experimental 
  stage 
  and 
  are 
  in 
  actual 
  pro- 
  

   duction 
  now 
  or 
  will 
  be 
  immediately 
  after 
  the 
  war 
  are 
  dealt 
  with. 
  

  

  Nothing 
  new 
  or 
  of 
  interest 
  can 
  be 
  reported 
  on 
  nylon, 
  fibroin, 
  fibers 
  

   from 
  corn, 
  chitin, 
  ossein, 
  lichenin, 
  Iceland 
  moss, 
  alginates, 
  or 
  agar- 
  

   agar. 
  There 
  are, 
  however, 
  developments 
  of 
  great 
  significance 
  in 
  the 
  

   protein-base 
  fibers 
  such 
  as 
  casein 
  and 
  soybean, 
  which 
  have 
  been 
  de- 
  

   veloped 
  to 
  a 
  considerable 
  extent 
  in 
  the 
  past 
  3 
  years. 
  There 
  has 
  also 
  

   been 
  a 
  rapid 
  advance 
  in 
  the 
  vinyl 
  resin 
  group 
  and 
  in 
  the 
  thermoplastic 
  

   resin 
  groups. 
  

  

  THERMOPLASTIC 
  RESINS 
  

  

  When 
  Dow 
  Chemical 
  Co. 
  produced 
  saran 
  in 
  1939 
  (mentioned 
  only 
  

   briefly 
  in 
  my 
  1940 
  paper), 
  no 
  one 
  believed 
  that 
  it 
  would 
  have 
  any 
  

   significant 
  possibilities 
  in 
  the 
  textile 
  industry. 
  It 
  has 
  seen 
  many 
  new 
  

   textile 
  applications 
  since 
  then. 
  

  

  The 
  raw 
  materials 
  for 
  these 
  monofilament 
  yarns 
  are 
  a 
  group 
  of 
  

   resins 
  from 
  unsymmetrical 
  dichlorethylene, 
  known 
  as 
  vinylidene 
  

   chloride 
  resins, 
  made 
  from 
  petroleum 
  and 
  brine. 
  Ethylene 
  is 
  made 
  

   by 
  cracking 
  petroleum, 
  while 
  chlorine 
  comes 
  from 
  the 
  electrolysis 
  of 
  

   brine. 
  They 
  are 
  combined 
  to 
  form 
  trichlorethane, 
  which 
  is 
  converted 
  

   with 
  lime 
  into 
  the 
  vinylidene 
  chloride 
  monomer. 
  This 
  product 
  can 
  

   be 
  readily 
  polymerized 
  to 
  form 
  the 
  long-linear-straight 
  chain 
  poly- 
  

   mers. 
  By 
  careful 
  selection 
  of 
  copolymers 
  and 
  control 
  of 
  the 
  poly- 
  

   merization 
  conditions, 
  many 
  different 
  polymers 
  can 
  be 
  formed. 
  These 
  

   resins 
  range 
  from 
  a 
  flexible, 
  moderately 
  soluble 
  material, 
  having 
  a 
  

   melting 
  point 
  of 
  about 
  158° 
  F. 
  to 
  a 
  hard, 
  tough 
  thermoplastic, 
  having 
  

   a 
  softening 
  point 
  of 
  350° 
  F. 
  or 
  more. 
  The 
  basic 
  resin 
  is 
  odorless, 
  

   tasteless, 
  and 
  a 
  nontoxic 
  powder. 
  

  

  One 
  of 
  the 
  several 
  methods 
  of 
  extrusion 
  is 
  the 
  one 
  of 
  crystal 
  orien- 
  

   tation, 
  which 
  produces 
  long 
  continuous 
  monofilaments, 
  tapes, 
  bands, 
  

   and 
  ather 
  shapes. 
  The 
  oriented 
  form 
  is 
  produced 
  by 
  extrusion, 
  sub- 
  

   sequent 
  plastic 
  deformation 
  as 
  by 
  stretching, 
  and 
  by 
  heat 
  treatment 
  

  

  