The ionic conductivity of polyoxyethylene-and polyoxypropylene-polyurethane networks containing sodium tetraphenylborate was studied as a function of temperature and salt concentration. The results can be rationalised in terms of free volume considerations. The fact that the WLF equation applies to the conductivity of these materials demonstrates that there exists a direct relationship between the ion conduction process and the viscoelastic properties of the networks.

No abstract

The viscoelastic behaviour of polyether-based polyurethane networks containing sodium tetraphenylborate was investigated by means of dynamic mechanical measurements. A quantitative analysis of the storage modulus dependence on temperature, frequency, and salt concentration gives rise to three superposition correlations, viz. frequency-temperature, frequencyconcentration, and concentration-temperature. The frequency-temperature superposition follows a WLF behaviour, while the other two are approximately linear expressions particularly well verified in the zone of the transition state, a) Part 1: cf. 14).The present work, based on measurements taken at several frequencies, is an attempt to correlate quantitatively the effect of the main parameters on the storage modulus variation. Experimental PartThe samples examined were the same used previously14) and consisted of poly(ethy1ene oxide) (PEO; M = 400) and poly(propy1ene oxide) (PPO; M = 425) both crosslinked with 4,4',4"methylidynetris(l,4-phenylene) triisocyanate and containing various amounts of sodium tetraphenylborate. Their preparation has already been described14) and their main characteristics are again summarized in Tab. I . Dynamic measurements were carried out on a direct dynamic viscoelastometer (Rheovibron model DDV 11) in the temperature range -50 to 100°C at four frequencies: 3 3 , 1 1 , 35, and 110 Hz.

Crosslinked polyurethane elastomers consisting of low‐molecular‐weight polyethylene oxide or polypropylene oxide segments crosslinked with an aromatic triisocyanate have been studied. Networks have been prepared containing different amounts of sodium tetraphenylborate. The effects of temperature and salt concentration on their viscoelastic properties have been investigated by modulus and loss‐tangent measurements. Variations of the storage modulus with salt concentration or network chemical structure are directly correlated with variations in the glass transition temperature. In fact, superposition of the various modulus plots on a reduced temperature scale, T‐Tg, suggests that there is no dependence on salt concentration or polyether chemical structure.

The ionic conductivity of polyoxyethylene-and polyoxypropylene-polyurethane networks containing sodium tetraphenylborate was studied as a function of temperature and salt concentration. The results can be rationalised in terms of free volume considerations. The fact that the WLF equation applies to the conductivity of these materials demonstrates that there exists a direct relationship between the ion conduction process and the viscoelastic properties of the networks.