| Autor: |
Gorbunova MA; Institute for Problems of Chemical Physics, Russian Academy of Sciences, Semenov Prospect 1, 142432 Chernogolovka, Russia. zav@icp.ac.ru.; Lomonosov Moscow State University, Leninskie Gory 1, 119991 Moscow, Russia. deniano@yahoo.com., Komov EV; Lomonosov Moscow State University, Leninskie Gory 1, 119991 Moscow, Russia. deniano@yahoo.com., Grunin LY; Volga State University of Technology, Lenin sq. 3, 424000, Yoshkar-Ola, Russia., Ivanova MS; Volga State University of Technology, Lenin sq. 3, 424000, Yoshkar-Ola, Russia., Abukaev AF; Institute for Problems of Chemical Physics, Russian Academy of Sciences, Semenov Prospect 1, 142432 Chernogolovka, Russia. zav@icp.ac.ru.; Moscow Institute of Physics and Technology, Institutskiy per. 9, 141700 Dolgoprudny, Russia., Imamutdinova AM; Lomonosov Moscow State University, Leninskie Gory 1, 119991 Moscow, Russia. deniano@yahoo.com., Ivanov DA; Institute for Problems of Chemical Physics, Russian Academy of Sciences, Semenov Prospect 1, 142432 Chernogolovka, Russia. zav@icp.ac.ru.; Lomonosov Moscow State University, Leninskie Gory 1, 119991 Moscow, Russia. deniano@yahoo.com.; Institut de Sciences des Matériaux de Mulhouse, CNRS UMR 7361, 15 Jean Starcky, F-68057 Mulhouse, France.; Sirius University of Science and Technology, 1 Olympic Ave, 354340, Sochi, Russia., Anokhin DV; Institute for Problems of Chemical Physics, Russian Academy of Sciences, Semenov Prospect 1, 142432 Chernogolovka, Russia. zav@icp.ac.ru.; Lomonosov Moscow State University, Leninskie Gory 1, 119991 Moscow, Russia. deniano@yahoo.com.; Sirius University of Science and Technology, 1 Olympic Ave, 354340, Sochi, Russia. |
| Abstrakt: |
The influence of the hard segment nature on the crystallization kinetics of multi-block thermoplastic polyurethanes containing poly(butylene adipate) (PBA) as a soft segment was investigated. Using a combination of FTIR spectroscopy, time-domain 1 H nuclear magnetic resonance (TD-NMR), differential scanning calorimetry (DSC), fast-scanning calorimetry (FSC) and wide-angle X-ray diffraction (WAXS), it was shown that aliphatic, cycloaliphatic and aromatic diisocyanates affect the phase separation efficiency of soft and hard segments. The best phase separation efficiency was observed for a sample containing aliphatic diisocyanate due to the development of a hydrogen bond network. The thermal history, phase separation and the degree of ordering of the polyurethane determine the polymorphic behavior of melt-crystallized PBA. The formation of a partially-ordered mesophase of linear aliphatic polyurethane leads to an increase in the crystallization rate of PBA at room temperature and the formation of thermodynamically stable α-crystals. The presence of bulk cycloaliphatic and aromatic diol-urethane fragments prevents the phase separation of PBA, which crystallizes after slow cooling in a mixture of α- and β-crystalline forms. The new nanocalorimetry technique allows the identification of a direct correlation between the phase separation and crystallization kinetics of the melt-crystallized PBA in a wide range of cooling rates - from 2 to 30 000 K s -1 . Particularly, ultra-fast cooling suppresses the nucleation of the β-phase of PBA resulting in slow crystallization of only α-modification at room temperature. The role of the polyurethane mesophase in the crystallization of the soft segment was discussed for the first time. |
