Anionic waterborne polyurethane dispersions based on hydroxyl-terminated polybutadiene and poly(propylene glycol): Synthesis and characterization

Nonpolluting systems based on anionic polyurethane aqueous dispersions were obtained. The prepolymer based on hydroxyl-terminated polybutadiene (HTPB) , isophorone diisocyanate (IPDI), poly(propylene glycol) (PPG), and dimethy lolpropionic acid (DMPA) were synthesized in bulk. After neutralization wit h triethylamine (TEA), the anionomer prepolymer was dispersed in water, fol lowed by a chain-extension reaction with ethylenediamine (EDA). The prepoly mers were characterized by Fourier transform infrared spectrometry (FTIR) a nd the average particle size of the aqueous dispersions was determined by l aser light scattering (LLS). The mechanical behavior of polyurethane-cast f ilms and the adhesive properties of the aqueous dispersions as coatings for wood were evaluated. It was observed that an increase in the HTPB content provoked an increase in the viscosity and in the particle size of the dispe rsions. The tensile strength and the modulus values of the films and the ad hesiveness of the coatings in wood were also increased by increasing the HT PB content. On the other hand, the elongation of the polyurethane-cast film s and the tackness of the surface coatings decreased as the HTPB was increa sed. (C) 2001 John Wiley & Sons, Inc.