Influence of varying hard segments on the properties of chemically crosslinked moisture-cured polyurethane-urea

Polyurethane prepolymers are widely used in the reactive hot melt adhesives and moisture-cured coatings. The chemically crosslinked moisture-cured formulation based on PEG-1000 and isophorone diisocyanate was prepared with NCO/OH ratio of 1.6:1.0. Trimethylol propane was used as a crosslinking agent. The excess isocyanate of the prepolymer was chain extended in the ratio of 2:1 (NCO/OH) with different aliphatic diols, and 4:1 with different aromatic diamines. The polymer network maturation during moisture cure was followed by dynamic mechanical thermal analyzer (DMTA) instrument. The thermal and dynamic mechanical properties of the crosslinked polymers were evaluated using thermogravimetric analysis, differential scanning calorimetric analysis and DMTA. Surface properties were evaluated through angle-resolved X-ray photoelectron spectroscopy. The present article discusses the physical properties of moisture-cured polyurethane-urea (MCPU) containing chemical crosslinks in the hard segment. The complete moisture-cured polymers showed amorous results toward room temperature modulus, tensile strength, hardness, thermal stability, and transparency. The surface properties showed the enrichment of soft segments. (c) 2005 Wiley Periodicals, Inc.