Preparation and physical properties of nonionic aqueous polyurethane coatings containing different side chain PEGME length

Abstract

AbstractNonionic aqueous polyurethane (NAPU) coatings were prepared by a prepolymer process using 4,4‐methylene bis(isocyanatocyclohexane), poly(tetramethylene glycol) with a molecular weight of 2000 g/mol (PTMG2000), ethylenediamine and a synthesized nonionic dispersing centers of various molecular weight produced by isophorone diisocyanate, N‐diethanol amine, and poly(ethylene glycol) monomethyl ether (PEGME) with different molecular weights. The dispersion properties of the NAPU emulsions, thermal properties of the NAPU casting films, and its tensile strength were studied. Further, the water vapor permeability (WVP) and waterproof of NAPU‐coated fabric were also examined. Our results showed that the surface tension and particle size of NAPU emulsion increase with the decrease in PEGME chain length. For the thermal properties, the melting point of soft‐segment of NAPU casting films was not affected by the PEGME chain length, but the heat of fusion of the soft‐segment was greatly affected. In particular, the NAPU with PEGME chain length of 2000 g/mol has two obviously crystalline endothermic peaks. The lower peak was attributed to crystallizing PTMG2000. The higher peak was attributed to the crystallizing side chain PEGME of Mw = 2000 g/mol. The WVP followed the order: NAPU with PEGME chain length 750 g/mol > 550 g/mol > 350 g/mol > 2000 g/mol, and the waterproof increases with increase in PEGME length. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008