Crystallinity of PVA component of PVA-PVC graft polymer prepared from the polymerization of PVC in PVA aqueous solution using KPS as catalyst was studied.
The separation of X-ray scattering curve of PVA component from that of graft polymer was performed by atomic structure factor, Compton scattering factor and weight fraction of component polymer.
Crystallinity of PVA component decreases with the increase of weight fraction of PVC component.
Half width of X-ray diffraction peak of PVA component is much broader than that of homoor blend PVA and influenced by number of grafting PVC molecules per PVA molecule.
Change of crystallinity of PVA component of the graft polymer with high temperature treatment differs from that of homo-or blend PVA.

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Vinyl isobutyl ether was polymerized by various metal sulfate-sulfuric acid complexes at room temperature and the effect of a catalyst on the polymerization was examined. According to the kind of a metal atom in a complex catalyst, the rate of polymerization and the molecular weight of polymer were decreased as following; Al³⁺>Cr³⁺>Fe³⁺>Mg²⁺>Fe²⁺>Co²⁺. The effect of metal atom on the stereoregularity of resultant polymer was almost the same order mentioned above. The amount of sulfuric acid contained in the unit weight of complex catalyst and pH value of an aqueous solution of catalyst have no relation to the results of the polymerization. However the less sulfuric acid was dissociated from a complex, the more active the catalyst became. Metal sulfates containing an appropriate amount of water have an activity for the polymerization of vinyl isobutyl ether, but their activities are less than that of their sulfuric acid complexes. From these results, it was concluded that the acidity of catalyst, i. e., the character of the bond between metal ion and sulfuric acid, had an important role for the polymerization of vinyl isobutyl ether.

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Copolymerization of acetaldehyde with n-butyraldehyde was studied using mainly a mixture of diethyl zinc and aluminum isopropoxide as catalyst at low temperature.
Polymerization reactivity of acetaldehyde or n-butyraldehyde was found to be increased by the presence of even a slight amount of another aldehyde. The maximum conversion was obtained by a nearly equimolar mixture of acetaldehyde and n-butyraldehyde monomers.
Each copolymer thus obtained was found to be a cocrystalline copolymer. Structures of copolymers were indifferent to the compositions of catalysts but almost controlled by the compositions of monomer.
The content of residual catalyst in copolymer varied with the composition of monomers and was decreased by the treatment with acetylacetone. Degree of removal of residual catalyst in polymer by acetylacetone-treating did not depend on the total amount of catalyst used in polymerization and also on residual content of catalyst in polymer but entirely on the composition of catalyst, viz., molar ratio of diethyl zinc and aluminum isopropoxide.
The copolymers of acetaldehyde and n-butyraldehyde, thus obtained, were of good thermal stability compared with their homopolymers. The copolymers formed from the nearly equimolar mixtures of acetaldehyde and n-butyraldehyde was with the least content of residual catalyst and of the best thermal stability.

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Binary copolymerizations of acetaldehyde, propionaldehyde, n-butyraldehyde and iso-butyraldehyde were investigated using Et₂AlNPh₂ as catalyst at -78°C. All the copolymers obtained were crystalline and had the lattice constants varying in a continuous way according to the copolymer composition. The infrared absorption bands due to the ethereal linkage of the copolymer also showed a continuous variation in relation to the compositions. The copolymers of some limited compositions, unlike the both homopolymers and the copolymers of other compositions, were completely soluble in toluene, chloroform or carbon tetrachlorides, but could not be separated into fractions having different properties with usual organic solvents. From these results it was concluded that these copolymers were to be a “cocrystalline copolymer”, which falls into the category of the isomorphous phenomenon of monomeric units.
Such a cocrystalline copolymer was also obtained by the use of EtAl (NPh₂) ₂, Al (NPh₂) ₃, AlR₃, Al (OR) ₃ or ZnR₃ as catalyst.
The copolymerizations of a higher aldehyde, such as n-heptanal or n-octanal, with some lower aldehydes gave also the cocrystalline copolymers, however, in these cases the cocrystalline copolymers obtained showed different types of X-ray diffraction patterns in regard to the composition of the charged monomer.
The copolymer polymerized with Et₂AlNPh₂ was shown to have a terminal group of -NPh₂ by UV-absorption method.
The thermal decomposition of the copolymer of acetaldehyde and n-butyraldehyde was investigated at various temperatures and the solution viscosities of the decomposed polymers were determined. From these results the mechanisms of the thermal decomposition was discussed in some detail. The apparent activation energy of the scission of the polymer chain was calculated to be 34kcal/mol.

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Polymerization of acetaldehyde was carried out by using metal sulfate-sulfuric acid complexes as catalyst. Effect of catalyst concentration on the polymerization was not remarkable in the range of 0.05-1.0%. The rate of polymerization was relatively rapid and the critical temperature above which high polymer could not be obtained was observed between -30 and -50°C.
It was possible to polymerize acetaldehyde in the presence of solvents or vinyl monomers, but copolymers of acetaldehyde, with vinyl monomers were not detected by measurement of infrared spectra. By dispersing the solid catalyst, degree of polymerization of polyacetaldehyde was increased remarkably, e.g., polymer having degree of polymerization above 30000 was obtained in high conversion.
Polymerization was retarded by basic compounds. It was suggested that the polymerization proceeds by cationic mechanism in liquid state. From the results of infrared spectra and Xray diffraction pattern, the polymer was confirmed to be amorphous.

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Polymerization of n-butyraldehyde, iso-butyraldehyde and methoxybutyraldehyde were carried out by using magnesium sulfate-sulfuric acid complex as catalyst in the temperature range between -30 and -78°C.
At -30°C, only iso-butyraldehyde polymerized slightly, and at -78°C, n-butyraldehyde and iso-butyraldehyde polymerized to relatively high conversion, but the polymerization of methoxybutyraldehyde was restricted in low conversion. Generally, effect of catalyst concentration on the polymerization of aldehydes was not remarkable in the range of 0.1-1.0%. The rate of polymerization was rapid considerably. Viscosities of polymers were increased some what by dispersing solid catalyst but the increase of viscosities was not so remarkable as in the polymerization of acetaldehyde. Poly (methoxybutyraldehyde), soluble in various solvents, was sticky elastomer, so it is considered to be amorphous. Poly (n-butyraldehyde) was soluble only in chloroform but poly (iso-butyraldehyde) was insoluble in various solvents. They were confirmed to be crystalline from the results of X-ray diffraction patterns. Chloral, acrolein and croton aldehyde could not be polymerized with metal sulfate-sulfuric acid complex.

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