Effect of polar forces on the viscoelastic properties of poly(propylene oxide)

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.