In nitrocellulose-acetone systems (cf. paper III) existence of holes is suggested in higher concentration than 87%. In the present study 13% of dibutyl phthalate is added to nitrocellulose and specific volumes and coefficient of thermal expansion are measured. Systematic deviation from the additivity of specific volume is observed over 70% in concentration, and the expected“packing of holes”did not occur. Moreover, by the addition of dibutyl phthalate, the dependency of the coefficient of thermal expansion on the degree of polymerisation disappeared. From these results it is supposed that dibutyl phthalate has pretty solvent power to nitrocellulose.

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Swellings of crosslinked polyvinylacetate in binary mixtures of solvents were studied and the composition of liquids in the two phases (the polymer free liquid phase and the swollen polymer phase) measured. Ten solvent pairs, non polar-non polar, non polar-polar and polarpolar solvent, were examined. Simplified theoretical relations for the equilibria were proposed and individual cases discussed.

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Fractionated polyvinyl alcohols with DP 140 and 3370 were selected. These polyvinyl alcohols were mixed in aqueous solution in various proportions and mixture films were prepared. They were air dried and subjected to the heat treatment. When the temperature of the heat treatment and the content of the lower molecular weight portion are not so high the lower molecular weight portion dissolves out by the swelling and the degree of the swelling is governed chiefly by the higher molecular weight portion. So long as the mean degree of polymerization is the same the heterogeneity has not a great influence on the swelling properties of the films.

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We found that dimethyl sulfoxide is the common solvent of polyvinyl alcohol and polyvinyl cyanoethyl ether up to 100mol%of the extent of cyanoethylation and studied the thermal stability in the dilute solution viscosity and the viscosity behavior in the stable conditions. The critical stable temperatures of these solutions are 50-60°C. In the higher temperature, polyvinyl cyanoethyl ether seems to take up the cleavage of the cyanoethyl group.Comparing the viscosity of the dilute dimethyl sulfoxide solution of polyvinyl alcohol with that of aqueous solution at 30°C, the former gives the higher [η] and the lower k′(about 0.4) in Huggins' equation, furthermore the greater a (0.82) and the smaller K (6.3×10^-4) in the equation [η]=KP^a (P: the degree of polymerization). From these results, one may be able to say that dimethyl sulfoxide is the very good solvent for polyvinyl alcohol at 30°C. Comparing the viscosity of the dilute dimethyl sulfoxide solution of polyvinyl cyanoethyl ether with that of the aqueous, methylcellosolve and acetone solution chosen for the respective extent of cyanoethylation, the former gives the highest [η] and the lowest k′ (about0.4) in the whole range of the extent of cyanoethylation, furthermore the distinct maximum [η] is shown in about 30 mol cyanoethylation, corresponding to the behaviours of the aqueous solution in the previous report.These results seem to show that dimethyl sulfoxide is also the good solvent for polyvinyl cyanoethyl ether of the various extent of cyanoethylation at 30°C.

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Linear, cyclic, branched and cross-linked dimethylpolysiloxanes have been synthesized. The reduced viscosity of dilute solution in toluene (25°C) is measured for those samples and studied the influence of molecular structure upon the viscosity behavior. Any difference in k′ value (so-called Huggins k′) can not be observed between linear and cyclic polymers. Regarding the k′ value for linear polymer as a standard (k′ is about 0.5) its value is larger for branched polymers and smaller for cross-linked polymers. For branched polymers, the relationship between the number of branching and Zimm's size factor g^3/2, coincides with the theoretical line below 2 for the number of branching but deviates from the line above 2. The same line of terdency seems capable of applying to the behavior of k′.

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It has been known that the plot of the reduced viscosity of high polymer solutions against their concentration gives minima at certain concentration, C. Taking [η] _c, as the reduced viscosity at the concentration, Cc, the numerical values of [η] _c·C_c fall into two classes with respect to the kind of the solution. In the first class, [η] _c·C_c, gives the value 2.5 and in the second class, it gives 0.1 approximately. Assuming that the polymer molecules can take spherical or rod-like configuration in the solution and that they can just contact with each other at the critical concentration, C_c, the results mentioned above can be derived theoretically.

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Polyelectrolyte of definite chain length and electric charge density was prepared by partial acetalization of polyvinyl alcohol with glyoxylic acid. Viscosities of aqueous solutions of the potassium salt of acetal were measured. It was found that when there exist more than 2.5 ionizable groups in a chain of P=1000, viscosity of solution shows proper behavior of polyelectrolyte. It may be said that the effect of electric charge of the chain on the shape of the molecule in solution is very large even when the charge density is very small.

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