Kazuo Kawahara

Excluded‐Volume Effects in Dilute Polymer Solutions. I. Equilibrium Properties

Data of the statistical radius 〈 S2 〉1 / 2 and the second virial coefficient A2 were obtained for sharp fractions of polychloroprene (PCP) in methyl ethyl ketone (MEK), n‐butyl acetate, and carbon tetrachloride at 25°C and in trans‐decalin at temperatures ranging from 1° to 50°C. MEK at 25°C and trans‐decalin at 2°C were found to be theta solvents for PCP. From these data two dimensionless quantities defined by αs2 = 〈 S2 〉 / 〈 S2〉0and Ψ = A2M1/2[4π3/2NA( 〈 S2 〉 / M3 / 2]−1 were calculated for all combinations of molecular weight M, solvent species, and temperature, where 〈 S2 〉0 is the value of 〈 S2 〉 under θ conditions and NA is Avogadros number. These two quantities should be functions of a single parameter z, usually known as the interaction parameter, which is proportional to M1/2. With the data for these quantities from the present experiments on PCP as well as from Berrys experiments on polystyrene, comparative tests of typical theories for the excluded‐volume effects on dilute polymer solutions ...

Excluded‐Volume Effects in Dilute Polymer Solutions. II. Limiting Viscosity Number

Measurements of [η] were made for seven fractions of polychloroprene (PCP) in methyl ethyl ketone, n‐butyl acetate, and carbon tetrachloride at 25°C and for three fractions of PCP in trans‐decalin at a number of temperatures ranging from 0.05° to 65°C. On a log–log graph paper, the values of αη3( = [η]/[η]θ) calculated from these data formed a composite curve when plotted against αs3( = 〈S2〉3/2/〈S2〉03/2) obtained from light‐scattering experiments under the same conditions. This curve is characterized by a relatively marked upward curvature in the vicinity of the origin, followed by a linear portion of unit slope. Its initial tangent has a slope of 0.65, which is much smaller than 0.81 predicted theoretically by Kurata and Yamakawa. Plots of αη3 vs the interaction parameter z were prepared by evaluating z for each αs by use of the Yamakawa equation. They were fitted by a single curve having a slight downward curvature, suggesting that no drainage effect manifests itself in the viscosity behavior of the sys...