Polyurethane (PU) networks based on hydrogenated hydroxytelechelic polyisoprene (HHTPI) and isophorone diisocyanate isocyanurate (IIPDI) were prepared and studied. Determination of the critical conversion point (p(c) = 0.58) was obtained experimentally through rheological measurements. This value was similar to the value predicted using the Macosko Miller model. Differential scanning calorimetry (DSC) analyses show that PUs with a high degree of phase separation is obtained (81% for [NCO]/[OH] = 1). This phase segregation decreased when hard segment content increased. Glass transition temperature of the soft segment, T-gs = -66 degreesC, was little affected by hard segment content. Thus, the resulting polyurethanes exhibit elastomeric properties. For [NCO]/[OH] > 1 ratios, a second transition at 70 degreesC was observed and attributed to hard segment interactions. Using swelling measurements, the solubility parameter delta, polyurethane-THF interaction parameter (x), crosslink densities (v(c)) and the molecular weight between crosslinks (M-c) were determined. (C) 2004 Elsevier Ltd. All rights reserved.