The scission of polymer chain by oxidation was studied in order to modify the molecular weight of high molecular weight polypropylene. Polypropylene powder was polymerized by the catalyst prepared from TiCl₈, dicyclopentadienyl titanium dichloride, sodium and hydrogen.
Oxidative reagents used were oxygen and hydrogen peroxide. The activation energy for the scission of polymer chain by oxygen at 98-136°C was 30.5 kcal/mol and the scission rate of polymer chain by hydrogen peroxide at 95°C was constant and independent with the change of hydrogen peroxide concentration. It is concluded that the modification of the molecular weight of high molecular weight polypropylene by hydrogen peroxide and oxygen may be considered to be available, but the modification by oxygen should be not favorable in general because of stench and yellowish coloration accompanied by oxidation.

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Radiation-induced polymerization of octene-1 was carried out in the temperature range of -196 to+50°C in both the liquid and solid states of the monomer. The following variables were studied.
1) Dependence of polymerization rate on temperature.
2) Effects of radical scavengers on the polymerization at various temperatures.
3) Dose rate dependencies of the polymerization rate at -78°C and +20°C.
4) Effects of various solvents on the polymerization.
The following results were obtained; 1) Although the Arrhenius plot of the polymerization rate did not yield a linear relation, the total polymerization rate was separated into radical and ionic contributions. 2) The rate of polymerization was proportional to the first power of the dose rate at +20°C and -78°C. 3) At relatively high temperature, the rate of polymerization was accelerated by carbon tetrachloride, while, the rate was retarded by benzene. On the other hand, at low temperature, the rate of polymerization was not affected by carbontetrachloride, while the rate was accelerated by benzene.
From these experimental results, it was concluded that a cationic polymerization is operative at low temperatures whereas a radical mechanism predominates at higher temperatures.

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The graftings of acrylonitrile and acrylamide to cellophane by the photolysis of carbonyl groups with Ultraviolet-light were studied. Carbonyl groups of cellophane were introduced by reacting with methylvinylketone. From the results of irradiation time-grafting percent and carbonyl groups percent-grafting percent, it was indicated that carbonyl groups were effectively used for the grafting. In the graft polymerization of acrylonitrile to cellophane, water was more available than dimethylformamide as the solvent. Good evidence for the graftings was obtained by compairing the solubility characteristics of the graft with those of a physical mixture of the cellophane and the homopolymer.

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The degree of cure for melamine resin was measured by “formaldehyde isolation test”described in previous paper (I) of this series.
The rate equation for curing of the resin was proposed in previous paper (III).
Here, the apparent rate constants of curing to C-stage were obtained as a function of molar ratio of formaldehyde to melamine, and the values decreased with increasing molar ratio of formaldehyde to melamine.

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The relations between the degree of cure of the resin and physical and electrical properties of melamine resin paper laminates were quantitatively studied.
The degree of cure of the resin was determined by “formaldehyde isolation test”.
The physical and electrical properties (P)-water absorption·impact strength·flexural strength·dimensional change·volume resistivity-are showed as functions of the degree of cure (the amount of formaldehyde isolated) as follows:
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(F: formaldehyde isolated (degree of cure), n: molar ratio of formaldehyde to melamine, A, B, a, b: const.)
The amount of formaldehyde isolated at the optimum degree of cure (F₀) is obtained from the equation (F₀=B·n^A).

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The crosslinking reactions of styrene-glycidylmethacrylate copolymers containing epoxy group as reactive group with n-butylamine in solution were studied determining the gelation point.
Apparent crosslinking density (including the intramolecular crosslinking) at gelation point was proportional to the reciprocal of initial concentration of epoxy group in reaction mixture. The slope of this straight line was dependent upon the reaction temperature and solvent.
Relations among crosslinking density, initial concentration of epoxy group and gelation time were discussed concerning inter and intramolecular reaction.
It was concluded that the crosslinking reaction in solution were influenced by the sizes and configurations of the dissolved polymers.

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