Single crystals of polyethylene terephthalate were obtained by crystallization from dilute solutions in various solvents. Spherulites, dendrites, twins and spiral growth were also observed. The selected area diffraction patterns of the single crystal show that the molecular axis tilts at about 25°. It was confirmed that the thickness of the lamelae are about 100Å, and it depends upon the crystallization temperature and the solvent.

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Single crystals of amylose were obtained by adding butanol to the dilute solutions in a previous paper. In this paper the fold structure of amylose helixes in single crystals was studied in details. The selected area diffraction pattern of the single crystal shows that the helixes of amylose molecule in lamellae are folded, their directions are normal to the wide surface of the lamellae and the elongated directions of the rectangular shaped single crystals coresspond to the a axis of the unit cell. The growing planes of single crystals were discussed with the diffraction patterns and the space group of amylose crystals. The single crystals of Schardinger dextrin were observed by optical microscope and studied by X-ray diffractions. It was found that the relation between the single crystals of amylose and α-Schardinger dextrin is analogous to the relation between polyethylene and n-paraffine.

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Polymerization of acetaldehyde, n- and iso-butyraldehyde were carried out by using three metal sulfates having the acidic strength of acidity function below 3.3. For each of these aldehydes the highest yield of polymers was obtained with cupric sulfate catalyst (calcinated at 230°C, for 4hr), next with aluminum sulfate catalyst (non calcinated) and the least with nickel sulfate catalyst (calcinated at 100°C, for 4hr). At the same polymerization condition, the degree of conversion of acetaldehyde was the highest and there was no remarkable differences in degree of conversion between n- and iso-butyraldehyde. Effect of catalyst concentration on the yield of polymerizatin of acetaldehyde was remarkable, and the increases of the yields and of the degrees of polymerization of the polymers were observed by dispersing the solid catalysts. The rate of polymerization with these metal sulfates was slower than that with metal sulfate-sulfuric acid complexes as catalyst. The degree of conversion of polymerization in toluene was far lower than that in n-hexane.
The structures of the obtained polymers were the same as those of the polymers with metal sulfate-sulfuric acid complexes.

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The polymerizations of acrylonitrile in aqueous solution of zinc chloride initiated by ammonium persulfate were investigated by using dilatometric technique under homogeneous conditions. The following results were obtained.
1) The rate of polymerization was given by _??_
This abnormal kinetic equation suggested that the complex between acrylonitrile and zinc chloride might behave as a reducing agent and accelerated the rate of decomposition of ammonium persulfate.
2) The degree of polymerization of the polymer obtained in this system was several times larger than that of the polymer obtained in organic solvents. This results were interpreted in terms of complex formation between acrylonitrile and zinc chloride which produced an increase in k_p²/kt.
3) In this system, a, a-diphenyl-β-picryl hydrazyl, iodine+potassium iodide (1: 1), ferric chloride or cupric chloride behaved only as a retarder (or inhibitor), where p-benzoquinone, hydroquinone, hydroquinone monomethylether, p-tert-butyl pyrocatechol, pyrogallol or methylene blue behaved as both a retarder (or inhibitor) and a reducing agent.

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Vinylpyrrolidone was grafted in its aqueous solution on to the various kinds of polymers (polyethylene, polypropylene, nylon-6 and viscose rayon) by pre-irradiation method. The accelerating effect of water on the grafting, which is generally recognized for the grafting onto hydrophilic polymers, is also found even for the hydrophobic polymers. This effect, however, cannot be observed in grafting at high temperature in some systems.
Various kinds of monomers (styrene, methyl methacrylate, methyl acrylate and acrylonitrile) were grafted in their emulsions onto the above stated polymers. In this method, the grafting does not depend on the monomer concentration in the broad range. This grafting is regarded as a special case of grafting in aqueous solutions of the monomer.
Furthermore, the grafting of methyl methacrylate onto polypropylene in its monomer vapor is similar to that in its monomer liquid, for the layer of monomer might cover the surface of the polymer in case of grafting in the vapor phase.

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Rapid thermal degradation of a copolymer at high temperatures gives monomers, yield of which, however, differs from that of monomers produced by pyrolysis of each component homopolymer. The difference is attributed to a different probability of splitting off of a monomer unit from the end of the polymer chain having a free radical according whether the neighboring monomer unit is same or not. This phenomenon is called “boundary effect”.
In the present paper a method for quantitative evaluation of the boundary effect is proposed. To this purpose a parameter β_A is defined as β_A= (P_AA-P_AB)/P_AA, where P_AA and P_AB are the probabilities of splitting off of a monomer unit A bounded by a monomer unit A and B respectively.
β_A is a constant depending solely on the degradation temperature and the combination of the two monomer species. For a given combination of monomers it can be calculated using the following equation from the monomer yield on pyrolysis of a random copolymer of known composition.
_??_
whereƒis the molar ratio of monomers in feed; r₁ is the copolymerization reactivity ratio of A monomer; Y₀ (A) and Y (A) are yields of A monomer from homopolymer and copolymer respectively;φ_A is mol fraction of A unit in the copolymer.
If α_A is defined as the fraction of A unit having the same neighboring unit relative to the total A unit in the copolymer, it is calculated from the equation α_A=1-{Y₀ (A)-Y (A) /φ_A}/Φ_Aβ_A.
α_A is a parameter expressing the structural distribution of A units in the copolymer. When β_A of A-B copolymer has been known, α_A can be determined and an information on the structural distribution of unknown sample may be obtained.
β_A's for the styrene-acrylonitrile copolymer and for the styrene-methyl methacrylate copolymer were determined by gas chromatographic analysis of monomer yields of several samples of known compositions, and the constancy of β_A regardless of the length of sequence was ascertained. Parameters of the structural distribution α_A of several commercial St-AN copolymers were also determined.

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Polypropylene fiber was grafted in emulsion with vinyl acetate by pre-irradiation method and its derivative was obtained by saponification. These grafted polypropylene fibers were examined in mechanical, and thermal properties, and dyeability.
Grafting of vinyl acetate induced crackings in the interior of the polypropylene fiber.(Other kinds of monomers such as styrene, methyl methacrylate, acrylonitrile did not induce the cracking). The dyeability for disperse dyes was examined in the change of the partition constant of dyes with the monomer grafted percents. Although the elasticity of elongation of the vinyl acetate-grafted polypropylene decreased rapidly with graft percents, that of the derivative by saponification was not affected at all. The thermal contraction of the fibers was increased by these graftings. The high flow resistance in melt, was observed, though these grafted fibers were soluble in decaline.

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