ポリイソブチレン濃厚溶液の粘弾性に及ぼす圧力の影響

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A rheometer was designed to measure the viscoelastic behavior of polymer melts and concentrated solution at high temperature under high pressure. By means of this apparatus, the dynamic viscoelastic properties were measured of concentrated solution (20wt%) of polyisobutylene which had a viscosity-average molecular weight of 6.5×10^5 in decalin. Measurements were made at 40℃, frequencies being varied from 0.025 to 6.3 sec^<^1>, under the pressure in the range from 0 to 1000 kg/cm^2. With the increase of pressure, both the dynamic viscosity and rigidity increased to the same extent as had been shown in the case of polymer melts. The time-pressure superposition, similar to the usual time-temperature superposition, was made to give a smooth master curve. In order to know how the shift factors depends on pressure, the iso-thermal compressibility of the same sample was determined at 40℃. From the above experiments the following conclusions can be made. (1) The specific volume of the solution can be related to the gauge pressure by Tait's equation, [numerical formula] (1) where V_p and V_0 are the specific volumes at gauge pressures P and 0 kg/cm^2 respectively. B and C are constants independent of pressure, and have the values of 760.7kg/cm^2 and 0.1829 for the solution studied. Assuming that the relative free volume is defined as the ratio of the free volume to the occupied volume, the relative free volume of the solution was derived from Eq. (1). [numerical formula] (2) where f_p, f_s and f_0 are the relative free volumes of the solution at gauge pressures P, P_s (reference pressure) and 0 kg/cm^2, respectively. (2) Combining Eq. (2) with Doolittle's equation, the expression for the dependence of the shift factor on pressure can be derived as follows: [numerical formula] This expression shows satisfactory agreement with experimental results.
社団法人日本材料学会の論文
1968-04-15

ポリイソブチレン濃厚溶液の粘弾性に及ぼす圧力の影響

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