Thermal conductivities of polystyrene and polyethylene were measured by the similar method, as described in the previous paper, with an improved apparatus. The thermal conductivity of polyethylene was fairly greater than those of polystyrene, polyvinyl chloride and its copolymers. The effects of substituents of the polymers on the thermal conductivity was discussed.

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Various samples of Nylon-6 which have different degree of crystallinity have been prepared and the influence of the crystallinity on iodine sorption isotherms has been investigated with these samples. The results obtained are the following: 1) The amounts of iodine sorpted from the dilute I2-KI aq. soln. where the Freundlich isotherms is proved to hold, fall down with the decrease of the moisture regains by Nylon-6 fibers. 2) As the crystallinity of the samples increases, the range of concentration where the iodine sorption increase sharply shifts to the higher value. 3) At the nearly flat part of the sorption isotherms, the difference in the amount of the sorption among the different samples disappear gradually with the increase of concentration and at about 0.8N the amount of iodine sorption become independent on the crystallinity of Nylon-6 and show the same value for all the samples.

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The effect of γ-ray irradiation on Nylon tape and fibers has been studied in vacuo and oxygen atmospheres. Flow points of samples increased by 10° with 20 Mrep irradiation in vacuo and decreased at the first stage in oxygen. The increase of solution viscosities with irradiation in vacuo indicates evidently the formation of cross-links. The efficiency of crosslinking reaction, Gc. l.=1.55, has been estimated from viscosity measunements. The tensile strength of samples has been slightly lowered by irradiation in vacuo and to a more extent in oxygen. Volatile pnoducts, produced from samples irradiated in vacuo were composed of 62% H₂, 30% CO etc., and those from samples irradiated in oxygen 13-20% H₂, 34% CO, 40% CO₂ etc. respectively. It should be noted that the amount of CO gas liberated by irradiation are about the same (in vacuo and also in oxygen). This fact suggests that CO gas origir ates from the main chain. The oxygen present in the atmosphere before irradiation was completely absorbed by the sample. It is concluded that the cross-linking efficiency of nylon with γ-ray irradiation is considerably lower than that of polyethylene because of the weakeness of the main chain structure containing CO-NH groups.

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2, 5-Bis (β-N, N-ethyleneureidoethyl)-tetrahydrofuran, 2, 5-bis (β-N, N-ethyleneureidoethyl)-furan and 2, 5-bis (β-N, N-ethyleneureidoethyl)-thiophene were synthesized by the reactions between ethyleneimine and each of 2, 5-bis (β-isocyanatoethyl)-tetrahydrofuran, 2, 5-bis (β-isocyanatoethyl)-furan and 2, 5-bis (β-isocyanatoethyl)-thiophene derived from levulinic acid and furfural. The three compounds were found to be excellent adhesives. Tetreamethylene bisethyleneurea and hexamethylene bisethyleneurea were prepared. In order to study the relation between the adhesive properties and the chemical structure of these five bisethyleneureas, the adhesion tests for wood were carried out. It was found that the structure of bisethyleneureas is closely related to the water proofing properties in wood adhesion.

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Vinyl benzoate was polymerized in bulk with benzoyl peroxide as an initiator. The rate of polymerization measured gravimetrically is proportional to the square root of the initial initiator concentration. The total energy of activation of the polymerization is 31.6kcal/mol.

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Polyvinyl alcohol (PVA) was prepared by alkaline hydrolysis of polyvinyl benzoate (PVOBz, block polymer prepared at 60°C in the presence of 0.2% BPO). The content of free carboxylic group of the PVA which lies between 0.5 and 0.8 per molecule shows chain transfer withbenzoyl groups of monomer or dead polymer molecule and this gives rise to chain branching. The intrinsic viscosity of the PVA increases with increasing degree of the conversion, so some branches exist which remain even after the hydrolysis. These may be from the chain transfer reaction with the tertiary hydrogene in the monomer or dead polymer molecule. The gelformation which, under some conditions, occurs at the final stage of the polymerization may be attributed to the chain branchings. The content of 1, 2 glycol bond of the PVA, which was measured from its reaction with periodic acid, is 1.2 per 100 vinyl bonds.

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As we previously stated¹⁾, the methylol group of the melamine rsin is easily alkylated with alcohols in the strong alkaline media to yield water soluble resins. In this report, the compositions of the resins prepared in the alkaline media were studied in detail. Methylol group was easily methylated with methanol in the strong-alkaline media, but not in the neutral for weak-alkaline media. Its reaction rate was proportional to both alkalicatalyst and methanol concentrations. The activation energy of the methylation reaction was roughly estimated about 15kcal/mol.

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The dimethylene ether linkages, which exist in melamine-formaldehyde reaction products and their partially methylated products prepared in strong-alkaline media, were determined quantitatively. It was concluded that they increase in proportion to the alkali-catalyst concentration and the time of reaction in strong-alkaline media, but were not found in neutral, or weak-alkaline media.

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