［ＰＶＡ‐ＰＡＡ］ゲルの力学的特性に対するＰＡＡ混入率の影響について

Abstract

Recently, a contractile [PVA-PAA] gel that responds to electric potential was developed. For various applications of the [PVA-PAA] gel, it is important that the tensile properties and the structure of the gel are clarified. In this paper, the effect of PAA concentration was examined to obtain the relationship between the tensile property and the structure. [PVA-PAA] aqueous solutions were gelled by freezing-thawing cyclic processing (freezing: -60°C/5hr, thawing: +15°C/5hr, number of freezing-thawing cycles: 5 cycle).The results obtained are summarized as follows:(1) All of the initial Young's modulus, apparent Young's modulus and maximum stress decreased as the PAA concentration increased. These behaviors are attributable to not only the decrease of cross-linking density in PVA polymer chains by mixed PAA but also the hindering of orientation of PVA polymer chains by PAA under the deformed condition.(2) Both the strain energy and the maximum strain reached maximum at PAA concentration: 5wt%. This behavior is observed at the PAA/PVA molar ratio smaller than 0.3.(3) PAA contributes to the degeneration of tensile property at an infinitesimal deformation region and to the improvement of elongation of PVA polymer chain at a large deformation region. At the break point, the decrease of tensile property was due to the decrease of cross-linking density by PAA.(4) From the above results, it is suggested that [PVA-PAA] gels form phase-separated networks.