Journal
POLYMERS FOR ADVANCED TECHNOLOGIES
Volume 15, Issue 11, Pages 669-675Publisher
WILEY
DOI: 10.1002/pat.528
Keywords
waterborne hyperbranched polyurethane ionomer; dispersions; thermal degradation; swelling; morphology
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A novel waterborne hyperbranched polyurethane acrylate for aqueous dispersions (WHPUDs) based on hydroxy-functionalized hyperbranched aliphatic polyester Boltorn(TM) H20 was investigated. The effects of structural composition and crosslinking density have been studied in terms of swellability by water, thermal degradation, viscosity changes as well as transmission electron microscopy (TEM) morphology. The swell ratio showed an increasing trend with the higher concentration of ionic group, which is due to the increased total surface area of particles. The results of thermogravimetric analysis (TGA) for cured WHPUD films indicated good thermal stability with no appreciable weight loss until 200 degreesC. The activation energies were evaluated and were found in the range 154-186 kJ mol(-1). It was observed that an increase in hard segment content provoked the increases in thermal degradation temperature and activation energy of waterbome dispersions. The transmission electron photographs revealed that the average particle sizes of aqueous dispersions were in the range 30-125 nm. Owing to the enlargement of the stabilization site, the particle size decreased as the content of carboxyl group and degree of neutralization increased. The viscosity of WHPUDs increased rapidly with increasing the degree of neutralization. Moreover, water showed a favorable viscosity reduction effect. Copyright (C) 2004 John Wiley Sons, Ltd.
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