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The aim of this study was to estimate the structure of new polyurethanes with the potential to be used in medicine. Atactic poly[(R,S)-3-hydroxybutyrate], obtained via a ring-opening polymerization, and polycaprolactonediol or polyoxytetramethylenediol were used to built the soft segments. 4,4 0 -methylene dicyclohexyl diisocyanate and 1,4-butanediol were the components to form hard segments. At FTIR spectra of obtained polyurethanes the bands attributed to AN¼ ¼C¼ ¼O groups completely disappeared, similarly as these of AOH groups and the new band characteristic for stretching vibrations of bonded urethane ANH groups appeared. Polyurethanes with low-mo-lecular weight were obtained. The observation of FTIR and 1 H-NMR spectra had been suggested that NH groups form two types of hydrogen bonds: with C¼ ¼O urethane (possibly with ester group) and ether groups. An addition of poly[(R,S)-3-hydroxybutyrate] caused the slight increase in number of urethane-urethane hydrogen bonds. For some of polyurethanes (based on polyoxytetramethylenediol) the allophanate structures were obtained. V C 2012 Wiley Periodicals, Inc. J Appl Polym Sci 125: [4285][4286][4287][4288][4289][4290][4291] 2012

The thermal, mechanical and thermo‐mechanical properties of polymer compositions, containing synthetic biodegradable polymers i.e. polylacide (PLA) and aliphatic‐aromatic copolyester (BTA), natural biopolyester n‐PHB and its synthetic atactic analog (a‐PHB) were investigated. Thermal properties of the polymer compositions were studied by means of DSC . The compositions of various polymer weight ratio were tested. Compositions containing BTA and n‐PHB create polyphase systems, what was confirmed by DSC. In this case the two Tg and two Tm values were observed. Polymer compositions containing PLA and BTA showed different behaviours. At the BTA content up to 30 weight % only one Tg and one Tm were indicated. At the increase of the BTA content to 50% weight and above, the two Tg, and two Tm were observed. Mixtures of BTA with n‐PHB, PLA and with a‐PHB show considerably greater values of the strain (ε) in comparison with initial polymers (n‐PHB, PLA). It was found that in contrary to mixtures containing PLA, at the BTA content in the mixture with n‐PHB above 50% of weights increases not only the strain, but also the stress at break (σ). Strong increase of the ε value in PLA/a‐PHB mixtures with the content of a‐PHB above 30% of weights were observed.