Methods for treating data of excluded volume effects in dilute polymer solutions

Abstract

AbstractA method for estimating the free‐energy parameter B appearing in the excluded volume parameter z defined by z=(4π)−3/2B(M/〈s20〉)3/2M1/2 was proposed based on the semiempirical equation of STOCKMAYER N0B/2A2 = 1 + Sz/a3 (S = 2,865) for the second virial coefficient A2, where N0 is the AVOGADRO number and a is the expansion factor. When the temperature dependence of B is given by B = B0(1−Ω/T) the definition of z and the STOCKMAYER equation yield the relation The plot of (1−Ω/T)/A2 versus M2(1−Ω/T)〈s2〉−3/2 due to this equation was made for the existing experimental data on the theta solvent and was found to give a straight line. The values of B0 and S obtained by this plot agreed with the value determined by BERRY's method and the theoretical value S = 2,865 respectively. In order to investigate the behaviour of a at small z, the data of a near the theta temperature were analyzed with an approximate equation a5 ‐ a2 = 1,914z which fits to the perturbation theory and to the YAMAKAWA‐TANAKA equation of a in the region 0<z<5.