Polymerization of acrylonitrile in aqueous medium initiated by potassium persulfate (KPS)-sodiumbisulfite (NaHSO₃) redox system has been investigatedkinetically with the aid of dilatometry and viscometry. The results obtained areas follow;
1. Apparent rate of polymerization Rp is represented as follows;
2. The overall activation energy is 13.0 kcal/mol in the temperature range of 15 to 40°C.
3. The number average degree of polymerizationdecreases as catalyst concentration and temperature increase, and higher molecular weights of polymer were obtained as monomer concentration decreases.

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In the case of redox copolymerization of acrylonitrile and 2-vinyl pyridine initiated by sodium persulf ate-sodium bisulfite in aqueous medium, the composition distribution was examined. The distribution results was in fairly good agreement with that computed by the skeistmethod using IVIRR values which were calculated from the Price's values of Q and e.

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The kinetics of the cationic copolymerization of isobutene with styrene or with a-methylstyrene in methylene chloride or toluene using TiCl₄ catalystwas studied at -78°C. The rates of copolymerizatin increase as a simple function of the concentration of the more reactive component in monomer mixture, but the intrinsic viscosities of copolymers are very much smaller than those of the corresponding homopolymers. These phenomena may be kinetically explaind by takinginto consideration of the “cross-trasfer reactions” between the propagating ions and the related monomers, though the chemical mechanisms are still uncertain.In the isobutene-styrene system, the values of the cross-transfer constants are several times larger than those of homopolymerization, while in the case of isobutene-α-methylstyrene system, these values are above thirty times larger than those of respective monomers. The reactivity ratio of those systems estimated from the chemical analysis vary with the polarity of solvents used.

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Effect of irradiation on tensile strength and elongation of PVA and acetalized PVA films has been studied. The filaments were irradiated at room temperature in vacuo and in air. Tensile strength of PVA films heat-treated at 140°C increases by about 15% by irradiation and that of the films heat-treated at 200°C remains almost unchanged whereas elongation of these films decreases with increasing radiation doses. Tensile strength and elongation of acetalized PVA films decrease remarkably with increasing doses, and the decrement is larger where the films were irradiated in air than in vacuo.

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Preventive methods of colorisation at heat treatment for polyvinyl alcohol fiberobtained from liquid ammonia spinning process are investigated.The colorisation are prevented by addition of small amount of ammono-acid (Ammonium acetate, Acetamide, Urea, Ammonium chloride etc.) to dope, and further more, the fiber obtained improve its properties by this method.This method can be also applied to ordinary wet spinning process.

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Thermal degradation rate of several kinds of polyvinyl alcohol (PVA) are measured with thermobalance. It is found that the value of activation energy obtained differ with different samples the results agrees with the mechanism at heat treatment descrived preciminaly report. Accordingly, structural difference of PVA affects also activation energy of thermal degradation.

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Tensile tests on drawn filaments of polyethylene, polyethylene terephthalate and nylon 6 have been carried out from-200°C up to 200°C. Temperature dependence of the initial elastic modulus calculated from the initial slope of the stress-strain curve is shown to be quite similar to that of the dynamic elastic modulus. For example, abrupt drop of the initial elastic modulus of polyethylene take place at about-120°C and about a certain temperature above the room temperature. These drop correspond to γ-and α-dispersion in the dynamic mechanical properties of polyethylene, respectively. Analogous correspondence between initial elastic modulus and dynamic modulus is obtained for other polymers. The value of the initial elastic modulus is always smaller than that of the elastic modulus observed by the dynamic method. This difference can be attributed to the nonlinear viscoelasticity in the large deformation. While the ultimate strain increases with increasing temperature, the dependence of the yield strain is small. The dependence of the tensile strength and yield strength on temperature are parallel with that of the initial elastic modulus.

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Mesuarements of resilience were made on 13 typical polymers by using Dunlop Tripsometer at various temperatures. The crystalline polymer showed dispersions attributed to transitions in amorphous regions and to shose in crystalline regions. The clystalline transition was observed as a conspicuous melting dispersion at high temperatures, and besides, another dispersion in crystalline region was found in polyethylene, polytetrafluoroethylene, Nylon 66 etc. Several dispersion regions correlated to the transitions of amorphous regions were also found in crystalline polymers. The main dispersion at high temperatures correlated to the transition region of segmental motion was flat and broad. And the dispersions at low temperature was generally correlated to the transition of the short amorphous chains. The main dispersion temperature of linear polymer was proportional to the softening temperature.

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It is assumed that the structures avaiable for the segment of crystallizable polymer can be classified into two kinds the energetically stabilized special structure (crystal structure) and the other (amorphous structure). These structures are different with regard to the internal free energy of segment, the binding free energy between segments, and the segment-segment and segment-solvent interactions. On these assumptions, we have calculated the partition functions both for an independent crystallizable polymer chain and for crystallizable polymer solution by means of the methods of the eigen value problem of matrix and the Flory's theory of polymer solutions in the 0th order approximation.

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Temperature and concentration dependence of the degree of crystallinity of the segment was analyzed by applying the results of the previous paper. The problems of phase separation was also considered. It was shown that phase separation into two phases which are different not only in the concentration but also in the degree of crystallinity of the segment, is possible in crystallizable polymer solutions. Second virial coefficient was calculated, and it was shown that the second virial coefficients for crystallizable and noncrystallizable polymers of the same polymer are different. The partition function of the imperfectly crystallizable polymer solution was also calculated.

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Making use of the rotational oscillation type viscoelastometer, viscoelastisity of acetone solutions of nitrocellulose was measured, covering 10-40% inconcentration, 20-40°C in temperature and 10^-3-10 CPS in frequency. Degrees of polymerization of the samples used were 196, 133 and 48. For the sample of D. P.=196 dynamic elastisity could not be observed and the dynamic viscosity was 0.3-0.5 poise at the concentration, 11.3%. At the concentration, 25.3%, the dynamic elastisity increased from 1.0 to 100 CGSU and the dynamic viscosity decreased from 1000 to 3 poise for the frequencies changed from 0.1 to 10 cycles. In the case of the sample of D.P.=48 the dynamic viscosity was ca. 100 poise and the dynamic ela-stisity was 60-70 CGSU at the concentration of 49%, but at rhe concentrations below 34%, dynamic elastisity could not be observed, and the viscosity behavier was considered to be Newtonian.

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It is shown that the viscoelasticity data of our XIIIth report obey Ferry's temperature reduction law. The characteristic temperature T_s in WLF equation was found to vary from 144 to 180° K as the concentration changes from 30 to 40%.
The reduction factor for the dynamic viscosity coincides with that for the dynamic modulus.

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Ferry's reduction law of concentration, i.e.,
is found to be applicable to the viscoelasticity of acetone solution of nitrocellulose, which has been reported in the previous paper XIII. A linear relationship between log_aC and log 1/C is also found, where a_C is the so-called reduction factor of concentration and c is concentration. Below 30% concentration, there exists a linear relationship between the logarithm of zero shear viscosity log η₀, , and C, whereas above that concentration log η₀ has more serious dependence on concentration. Activation energy of relaxation process extrapolated to zero concentration is 3.5 kcal/mol, which is very large compared with that of pure solvent, 1.6 kcal/mol.

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“Reduction law of degree of polymerization” is found to be applicable to the result of the previous paper XIII of this series.In this law, the reduction factor is proportional to the 0.3 power of reduced degree of polymerisation. Overall reduction law, concerning with temperature, concentration and degree of polymerisation, is written as follows:From the results of the XIV, XV and this papers, the spectrum of relaxation time of concentrated solution of nitrocellulose in acetone was calculated in the range of relaxation time from 10^-5 to 10⁰ second. Combining our result with Ferry's one, we have obtained the spectrum of relaxation time in the wider region for the solution of cellulose derivatives.

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The dependence of intrinsic viscosity of sedimentation constant and diffusion constant upon molecular weight, may be given by [η] =K_IM^α, S₀=K_IIMβ and D₀=K_IIIM^-γ respectively. Then, the relationships among each group of the parameters K_I, K_II, K_III and α, β, γ can be obtained through use of the Flory-Fox theory for intrinsic viscosity, Svedberg's equation for sedimentation and Einstein's equation for diffusion respectively, making use of these relation-ships the experimental values of parameters were examined for a few polymer-solvent systems.

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The average molecular weights Irisv M_SV and M_DV are obtained by combining Flory-Fox theory of intrinsic viscosity, with Svedberg's equation for sedimentation and with Einstein's equation for diffusion, respectively.For the purpose of examining the validity of the molecular weight distribution curves obtained by the sedimentation velocity and diffusion methods, the observed values for the following average molecular weights are compared with those calculated from the distribution curves; weight average molecular weight M_w, number average molecular weight M_n, and M_SV, M_DV and M_SD (defined in part I and II of our studies)

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Even if the relations between sedimentation constant and molecular weight and between diffusion constant and molecular weight are unknown respectively, the molecular weight distribution curve can be determined by Svedberg's equation through use of the weight distribution curves with regard to the sedimentation constant and the corresponding diffusion constant. For polystyrene-methy-ethyl-ketone system the average molecular weights calculated from these distribution curves give a satisfactory agreement with the observed values.

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