Effect of polar forces on the viscoelastic properties of poly(propylene oxide)
| Autor: | E. F. Cuddihy, J. Moacanin |
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| Rok vydání: | 2007 |
| Předmět: | |
| Zdroj: | Journal of Polymer Science Part C: Polymer Symposia. 14:313-322 |
| ISSN: | 1935-3065 0449-2994 |
| DOI: | 10.1002/polc.5070140124 |
| Popis: | When lithium perchlorate is dissolved in ethers, volume contractions are observed which are caused by strong interaction forces between the field of Li+ and polarizable ether oxygens. The effect of these forces on the viscoelastic properties of both low (commercial PPG 2025) and high molecular weight/poly(propylene oxide), containing varying amounts of dissolved lithium perchlorate (LP), was investigated by means of dilatometric, modulus, and damping constant measurements over a temperature range between -SO and 80°C. The glass transition temperature, Tg, for PPG 2025 was raised from −70 to 40°C. for 25 wt.-% LP. Neither modulus nor damping curves could be superposed on the reduced T-Tg temperature scale. Below 15 wt.-% LP the various properties could be interpreted as resulting from the superposition of the behavior of free polyether segments with that of segments nearest neighbors to LP. Above 15 wt.-% LP no free segments are left. The behavior of the high molecular weight polyether was similar, except that below 15 wt.-% LP the single Tg observed for PPG 2025 was split in two transitions, Tg for the polyether at −65°C, and another at −10°C. The latter is believed to be a transition for polyether helices stabilized by LP situated in the helix core. |
| Databáze: | OpenAIRE |
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