| Abstract: | This article presents the results of the synthesis and characterization of environmentally friendly polyurethanes based on renewable polyols, and specially highlights the use of Eucalyptus tar pitch, a byproduct of the charcoal making industry in Brazil, to obtain PUs. Eucalyptus tar pitch and castor oil PUs synthesized with MDI in THF, catalyzed by dibutyltin dilaurate, were prepared with NCO/OH equal to 1, and vacuum cured. The addition of Eucalyptus tar pitch to the formulation of PUs showed a tendency to increase the formation of rigid segments, and consequently, to modify thermal stability. SEM micrographs confirm this behavior, displaying different materials. Homogeneous polyurethane elastomers become rigid and acquire lamella structure with the addition of biopitch, as confirmed by tensile strength assays. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3287–3291, 2004 |
