Phase Behavior and Mechanical Properties of Siloxane-Urethane Copolymer
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Two series of siloxane-urethane copolymers were prepared from polydimethylsiloxane (PDMS) with a molecular weight of 1000 or 1800 which was used as a soft segment, 4,4′-diphenylmethane diisocyanate (MDI) and 1,4-butanediol (1,4-BD). Differential scanning calorimetry (DSC) demonstrated that the position (Tgs) and breadth (ΔB) of soft-segment glass transition of copolymers remained constant as the hard-segment content increased. Heat capacities at soft-segment glass transition of the copolymer (ΔCp) were 0.195∼0.411 J/g○C and heat capacities of pure PDMS (ΔCp0) were 0.571∼0.647 J/g○C, leading to the various ΔCp/ΔCp0 ratios. The ΔCp/ΔCp0 ratios decreased as the increasing of hard-segment content, showing poor phase separation. The FTIR spectrum confirmed the occurrence of hydrogen bonding in ether end-group of pure PDMS. The ether group of the soft segment led to interfacial mixing between soft and hard segments. The tan δ of the soft segment determined by dynamic mechanical testing (DMA) also identified the mixing of soft and hard segments. The mechanical properties of the copolymer were directly related to either the soft and hard segment contents or the chain lengths of soft and hard segments. The hard segment that reinforced the soft segment and interfacial thickness between soft and hard segment dominated the mechanical properties.
KeywordsDMA DSC heat capacities mixing siloxane-urethane copolymer
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- 1.P. E. Gibson, M. A. Vallance and S. L. Cooper, Development in Block Copolymer, Appl. Sci. Ser., Elsevier Press, London, 1982. Google Scholar
- 2.S. L. Aggarwal, Block Polymer, Plenum Press, New York, 1970. Google Scholar
- 3.N. S. Schneider, C. R. Desper, J. L. Illinger and A. O. King, J. Macromol. Sci. Phys. B, 11, 527 (1975). Google Scholar
- 9.R. A. Phillips, J. C. Stevenson, M. R. Nagarajan and S. L. Cooper, J. Macromol. Sci. Phys. B, 27, 245 (1988). Google Scholar
- 10.Mitsui Nisso Corp. Japan Kokai, Tokkyo, Koho, Jpn. Pat. 58,217,515, 1983 Google Scholar
- 11.V. Y. Kotomkin, V. A. Baburina, E. P. Lebedov, V. A. Bylev, T. E. Yasmikova and V. O. Reikhsfeld, Khimyai Parki Primonennie, Kremnii I Fosforogan, Soedin L, 23 (1980); Chem. Abstr., 95:43841d. Google Scholar
- 12.V. Y. Kotomkin, V. A. Baburna, V. P. Lebdev and Y. Y. Kercha, Plastic Massy, 27 (1981); Chem. Abstr., 95:43841d. Google Scholar
- 20.T. A. Speckhard and S. L. Cooper, Rub. Chem. Technol., 59, 405 (1986). Google Scholar
- 25.D. R. Paul, Polym. Mater. Sci. Eng., 50, 1 (1984). Google Scholar