Introduction From the recent studies of a new group of polyurethanes containing unsaturated bonds one may extract a few trends. One of them focuses on poly(ure- thaneacrylates) (PEUA) and poly(urethaneurea-meth- acrylates) (PEUMA) in which the presence of unsaturated bonds allows for their cross-linking by a radical polymerization [1–5]. In the papers by Oprea et al. [1–3] concerning thermal stability of PEUA and PEUMA two maxima of mass loss in their thermograms were revealed. Furthermore, these authors showed that polymers containing cross- linking bonds exhibit an increase of degradation temperature of up to 15–25°C in comparison with polymers containing double bonds. Their thermo- gravimetric analysis revealed also a decrease in activation energy of up to 20–30% for PEUA [1] and 10–15% for PEUMA [2], respectively. These changes, in authors’ opinion, may be caused by the dehydration of the –COO –+ NH 3 structure and poly- merization of double bonds. The group of polymers containing unsaturated bonds includes also poly(ester-siloxane)ure- thanes [6, 7]. The presence of urethane groups and fragments of polysiloxane chains allows for obtaining polymers with sufficiently thermal and mechanical properties. The studies on mechanical properties and thermal stability of cross-linked elastomers revealed their dependence on chemical composition and cross-linking density. As shown in [6–8], these properties are strongly influenced by hard segment content in the structure of elastomers. Dynamic- mechanical thermal analysis measurements of poly(ester-siloxane)urethanes exhibited an influence of chemical composition of polymers and the type of the used cross-linking agent on their thermo-mecha- nical properties [6]. The intercross-linked networks of siliconized polyurethane-epoxy/unsaturated polyester coatings also constitute an important group of cross-linked polymers [8]. The thermal stability of these systems was studied using a differential scanning calorimetry and thermogravimetric analysis. The studies proved that the presence of urethane groups in these systems reduces their thermal stability. Moreover, the polymers containing urethane groups have lower glass transition temperatures (T g ) than the unmodified ones. Urethane groups in elastomers increase their tensile strength and thus provide possibilities of wide application. The present paper discusses the influence of a chemical structure on the thermal and dynamic- mechanical properties of cross-linked poly(esterure- thanes). In particular, the influence of the [NCO/OH] molar ratio and the type of the used cross-linking monomer was studied. The obtained results show also that the poly(esterurethanes) which contain cross- linking agent are more stable than the reference materials without cross-linking. 1388–6150/$20.00 Akadémiai Kiadó, Budapest, Hungary © 2007 Akadémiai Kiadó, Budapest Springer, Dordrecht, The Netherlands Journal of Thermal Analysis and Calorimetry, Vol. 88 (2007) 2, 419–423 THERMAL AND DYNAMIC MECHANICAL ANALYSIS OF CROSS-LINKED POLY(ESTERURETHANES) Lidia JasiÕska 1* , A. Balas 1 , J. T. Haponiuk 1 , G. Nowaczyk 2 and S. Jurga 2 1 GdaÕsk University of Technology, Faculty of Chemistry, Department of Polymer Technology, Narutowicza St 11/12 80-952 GdaÕsk, Poland 2 Adam Mickiewicz University, Faculty of Physics, Department of Macromolecular Physics, Umultowska St 85, 61-614 PoznaÕ, Poland New cross-linked poly(esterurethanes) (PEU) based on unsaturated olygo(alkyleneester)diol (OAE), 4,4’-diphenylmethane diisocyanate (MDI) and styrene or methyl methacrylate as curing monomers were prepared. The synthesis of PEU was performed in two steps. In the first step OAE was obtained from adipic acid, maleic anhydride and ethylene glycol. In the second step a prepolymer was obtained in a reaction of OAE with different amounts of 4,4’-diphenylmethane diisocyanate followed by cross- linking using previously mentioned curing monomers. The influence of structure of the poly(esterurethanes) on thermal and dynamic mechanical properties is studied. Thermogravimetric analysis shows that cross-linked poly(esterurethanes) demonstrate high thermal stability. Moreover the dynamic mechanical thermal analysis shows that the presence of styrene cross-linking chains in polymers lead to the phase separation in cross-linked poly(esterurethanes). Keywords: dynamic-mechanical analysis, poly(esterurethanes), thermal stability * Author for correspondence: lidia@urethan.chem.pg.gda.pl