Structural studies of polyoxymethylene (POM) have been undertaken by use of the infrared and X-ray measurements from the point of view of the simplicity of the chemical structure and of the interesting helical configuration of the molecule in crystalline state. In this preliminary report the method of preparation of thin films of this polymer suitable for the infrared measurements is described. The film samples (oriented or non-oriented) of required thickness (5-10μ) can be easily prepared by this method. The polarized infrared spectra of POM in the 3500-400cm^-1 region were reproduced.

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The results of the light scattering and viscosity measurements with poly-(vinyl acetate) had been reported in the previous papers Part II and III. Some considerations were made on the radius of gyration, second virial coefficient, Flory's constant and molecular constant of polymer dimension on the basis of the results. The relationships between weight average root-mean square of molecular radius , second virial coefficient A₂ and weight average molecular weight M^ω in acetone and methyl ethyl ketone were given by: and . The Flory's constant φ corrected to the perfectly homogeneous specimens were 2.6×10²⁸in acetone and 2.8×10²⁸ in methyl ethyl ketone, respectively, ([η] is represented in ml/g). The values of and all of which are constants concerning with the stiffness of polymer chain, were calculated. The obtained values were 6.5Å, 2.10 and 78, respectively. From the comparison with those of other polymers, it was concluded that the stiffness of polymer chain in solution is in the order of: polystyrene≥polyvinyl acetate>polymethyl methacrylate.

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The new method of calibration of light scattering photometer by some standard scattering solids is described here. The scattering intensities of four optical glasses and two high polymer solids were measured. In order to check the purity of their scattered lights, the effect of the primary beam width, the depolarization of the scattered light, the existence of the fluorescence, and the dissymmetry were measured. From these measurments, it was found that the optical glasses were suitable for the standards, especially among those the one having the highest content of lead was the best. The reduced scattering intensities at 90°(R₉₀) on the same optical glass were measured by eight different instruments in Japan. The results were satisfactorily coincident with each other.

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The effect of agitation on polymerization of acrylonitrile both in aqueous medium and in emulsion was investigated by the method of dilatometry and viscometry, initiated by persulfatetriethanol amine redox-system and persulfate alone. As the results the induction period and the number average degree of polymerization has not been affected by agitation of the system, where as the over-all polymerization rate was reduced to about 65% values by agitation comparied with non-agitation system, in aqueous medium, but in emulsion system, the more quantity of sodium lauryl sulfate be added, the less difference was depressed. It appears that the agitation led to aggregation of particles and reduced the number of active reaction nuclei. Otherwise sodium lauryl sulfate increases the stability of particles. The apparent activation energy proved to no effect by agitation and equal to about half of the decomposition energy of initiatores.

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Saponification rate of polyvinyl acetate, polymethyl acrylate and vinyl acetate (VAc)-methyl acrylate (MA) copolymers with different compositions were measured in acetone-water mixture in the presence of NaOH catalyst, and the effect of composition of polymers on the reactivity of the unit molecules (VAc and MA) was investigated. The initial rate constant of saponification increased with increasing VAc content of polymers. The increase of saponification rate of VAc-unit was relatively small when compared to that of MA-unit. The appearent rate constant generally changed with the degree of saponification; in respect to this behaviour copolymers were intermediate between the two homo-polymers. The correlation between the composition of polymers and the initial rate constant was treated theoreticaly, and the effect of the neighboring groups was qunantitatively clarified.

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Solution polymerization of vinyl acetate was carried out in octyl-, dodecyl-, hexadecyl-, octadecyl alcohol, in nitrogen stream and at atmospheric pressure by using BPO as an initiator. Similar experiments with ethyl and phenyl alcohol were carried out in sealed tube containing nitrogen. The polymerization yield was ordinary not less than 80%. The viscometric degree of polymerization varied with the condition of polymerization and the kinds of alcohol, but in all cases it was less than 100.

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Properties as srufactants, such as surface tension and foaming, of 10 saponified products of polyvinyl acetate obtained by solution polymerization in higher alcohols were measured and compared with various surfactants now in market. It was found that smaller the molecular weight and larger the alkyl radical, they are more useful and powerful as surfactants.

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γ-ray emulsion polymerization of methyl methacrylate (MMA), vinyl acetate (VAc) and styrene (St) has been carried out with cationic emulsifiers. Stable emulsions with monomer concentrations upto 50 wt%, were obtained. The rate of polymerization of MMA was proportional to 0.3 power of the dose rate. The overall activation enargies calculated by experiments at different temperatures were 5.7kcal/mol for VAc, 6.7kcal/mol for MMA and 6.2kcal/mol for St. It was obserbed with all the monomers used, that the degree of polymerization increases with temperature.

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The effect of added salts on the rate of polymerization in r-ray induced emulsion polymerization of methyl methacrylate has been investigated. Polymerization in the presence of nonionic detergents and 0.2mol/l of salts was carried out at 10% monomer concentration. The rate of polymerization was constant until the conversion reached 30%. Beyond 30% conversion the polymerization rate decreased in the order of NaCl>NaOAc>NaBr >Fricke solution>none>NaNO₃. No polymerization occurred in the presence of NaI. The mechanism of these reactions may be partly considered in this report. Maximum rate of polymerization was obtained in the vicinity of 0.2mol/l of NaCl concentration. Usual initiators (potassium persulphate and hydrogen peroxide) increased the rate. In various pH, the rate was constant in the initial stage, but gradually increased in the final stage.

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