Phase separation studies in RIM polyurethanes catalyst and hard segment crystallinity effects

R. E. Camargo, Chris Macosko, M. Tirrell, S. T. Wellinghoff

Research output: Contribution to journalArticlepeer-review

48 Scopus citations


Polyurethanes were prepared from pure 4,4′-diphenylmethane diisocyanate (MDI), 1,4-butane diol (BDO) or 1,2-ethane diol (EDO) and α,ω-hydroxyl poly(propylene oxide) (PPO) by reaction injection moulding (RIM). Hard segment (MDI + BDO or EDO) level was 45-50 wt%. The PPO had about 20% ethylene oxide copolymerized in at the chain ends to provide 80% primary OH end groups. Mn was varied from 2000 to 4000. Dibutyl tin dilaurate catalyst and mould temperature were varied. Dynamic mechanical, wide-angle X-ray, differential scanning calorimeter, molecular weight and tensile elongation measurements were made on the RIM polyurethanes. At low reaction rates (low catalyst or temperature) highly crystalline, well phase separated but low molecular weight polymers were produced. At high catalyst or temperature levels more poorly phase separated but high molecular weight, tough polymers resulted. Higher Mn PPO gave better phase separation and EDO gave higher melting temperatures. Preventing hard segment crystallinity by substituting asymmetric MDI or glycols resulted in phase compatibility.

Original languageEnglish (US)
Pages (from-to)1145-1154
Number of pages10
Issue number8
StatePublished - Aug 1985


  • crystalline hard segments
  • molecular weight
  • phase separation
  • polymerization rate
  • polyurethane
  • reaction injection moulding

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