Chain extension studies of water-borne polyurethanes from methyl ethyl ketoxime/ε-caprolactam-blocked aromatic isocyanates

S. Subramani, I. W. Cheong, J. H. Kim

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Abstract

A series of water-based blocked aromatic polyurethane dispersions (BPUDs) were prepared by prepolymer mixing process, using toluene 2,4-diisocyanate (TDI), 4,4′-di-p-phenylmethane diisocyanate (MDI), poly (oxytetramethylene) glycol (PTMG), dimethylol propionic acid (DMPA), methyl ethyl ketoxime (MEKO) and ε-caprolactam (CL). Particle size, viscosity, pH, molecular weight, storage stability, and deblocking temperature of the BPUDs were measured and compared. Chain extension of BPUD was carried out with three types of chain extenders, hexamethylene diamine (HMDA), isophorone diamine (IPDA) and tetraethylene pentamine (TEPA), at various de-blocking temperatures. Tensile and thermal properties of the chain extended BPUD films were investigated and results confirmed that MEKO-BPUDs de-blocked at lower temperature than ε-caprolactam-BPUDs. The Tg values of the chain extended BPUDs were higher than those of the BPUDs and pure PTMG. Improvement in the thermal stability confirmed the de-blocking and chain extension reaction of blocked PU prepolymers.

Original languageEnglish
Pages (from-to)328-338
Number of pages11
JournalProgress in Organic Coatings
Volume51
Issue number4
DOIs
Publication statusPublished - 2004 Dec 20

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All Science Journal Classification (ASJC) codes

  • Chemical Engineering(all)
  • Surfaces, Coatings and Films
  • Organic Chemistry
  • Materials Chemistry

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