As the melt viscosity of Saran varies with the kind and amount of plasticizer, the selection of a plasticizer is very important in the extrusion of Saran. In order to confirm these effects, the crystallization-rate was measured by the density gradient tube method. The crystallization-rate approaches a constant value as plasticizer content is increased, and log κ and τi show the same tendency. It was confirmed that specific volume of polymer and plasticizer had the additive properties, which was a basic assumption made in the calculationof the crystallinity of Saran. No change was found in the crystallization-rate even when. three kinds of plasticizers having different compatibilities with polymer were used.

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In the previous paper, it was pointed out that the crystallinity of filaments was less than 30% and that their mechanical properties change with the orientation of filament. In the present paper, the dichroic ratio of filament is measured with a Leitz polarizing microscope and the change in orientation of the amorphous part by stretching is investigated. Owing to difficulties in after-dyeing Saran filament, polymer is mixed with dyes or pigments and then extruded into filaments. The dichroic ratio is then measured from these filaments. Oil Red O was selected as the dye to be used. This dye is a diazo derivative having a comparatively large and long molecular dimension. It appears only in the amorphous part of the filament. So the dichroic ratio measured by this method is assumed to show the orientation of amorphous part. The dichroic ratio of plasticized filament increases linearly with stretch ratio up to a stretch ratio of 2.5. It is fairly constant between the stretch ratio of 2.5 and 4.5. It decreases distinctly at a stretch ratio of 4.7. On the other hand, the dichroic ratio of non-plasticized filaments increases linearly up to the stretch ratio of 3.0 and then decreases rapidly above this stretch ratio. The increase is considered to be due to the disorder of the arrangement of the amorphous part of the filament.

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It has been observed that in the extrusion of molten polyethylene through capillaries the shapes of extrudates become irregular beyond a critical values of shear stress shear rate. The dependences of shear rate and shear stress at incidence of irregularity upon various factors, such as, temperature, number-average molecular weight, kind of polymer and shape of capillary, were investigated.(1) As for the same kind of polymers, the critical values of the stress are almost independent on temperature and number-average molecular weight. On the other hand, the critical values of the shear rate are larger for smallar molecular weight and increase with increasing temperature. These results mean that the melt viscosity dominantly influences the critical values.(2) The critical values of the shear stress or the shear rate are remarkably dependent on the qualities of the low pressure polyethylene.(3) The critical value varies with the shapes of capillaries.

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The flow turbulence of molten low pressure polyethylene was studied by a capillary viscometer. Seven capillaries of various dimensions were used in the measurements. The critical shear rates 4Q_c/πR³ are almost independent on capillary radius R. The critical flow rate Q_c is proportionate to about 3 power of the radius R of an extrusion capillary (Q_c=KR³). These results are inconsistent with the results expected from the Reynolds' turbulence theory. On the other hand, it was supported by the so-called structural or fracture theory proposed by Tordella that the flow rates were scarcely affected by the approaches of capillaries, and the critical volume rates Q_c were remarkably influenced by the contour of the inlet of the capillaries. Various problems on the melt spinning of polyethylene such as the suitable dimension of capillary, the proper output, the relationship between melt viscosity and spinnability, etc., were also discussed.

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The melt viscosities of seven commercial polytrifluorochloroethylene were determined by parallel plate plastometer at the temperature of 227 to 315°C. These samples were the same as used in the previous work on the specific volume at the molten state. The modified plastometer of Dienes and Klemm was prepared (Fig. 2). For its high temperature duty, graphite roller bearings were used in place of their steel ball bearing, which held the loading shaft at right angle to the pressing surface of the test sample. The calibration of load was done by the hunging (spring) balances of 25 and 100 kg full scale (Fig. 3). The results were shown as Fig. 5 on NST 300 samples and Fig. 6 on NST 270 samples. The melt viscosities at 227°C were 3×10⁷ poise for NST 300 and 10⁷ poise for NST 270, respectively. They were nearly the same as the results of Bakelite Co. The apparent activation energy of flow was high and gave the value between 15 and 31 kcal, which differed from the values of 15 kcal reported by Bakelite Co. The cause of this discrepancy was discoused.

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The directional correlation function of proton pair of the sorbed water molecule affected by a rigid restriction of much greater energy compared with kT is obtained by the aid of rotational diffusion equation, and then its spin-spin and spin-lattice relaxation times, T₂ and T₁ are calculated. For the free water molecule sorbed with a negligible restriction, we can put the effect of potential in the anisotropy of rotational diffusion constants. For the mobile water we cannot neglect the intermolecular contribution due to translational Brownian motion of nearest neighbor molecules. Finally the influence of the sorbed water quantity on 1/T₂ is examined making use of the refined BET sorption isotherm

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The increase of molecular weight by intermolecular acetal formation of a mixture of polyvinylalcohols (PVA) having one and two aldehyde end groups was treated statistically. Let the degree of polymerization P of each initial polymer are equal, the ratio, i. e. number of PVA molecules having one aldehyde group to the total number of molecules is γ and the ratio, i. e. number of reacted aldehyde group to that of initial ones is, β, then the number average molecular weight P_n, and the weight average molecular weight P_w may be represented as follows: The β at gel point is 1/(2-γ). However these equations fit only for the case P≥50. These results were applied to expermental results reported before.

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A copolymer of 80% vinylidene chloride and 20% acrylonitrile by weight was prepared. It was found that solutions of the copolymer in cyclohexanone and tetrahydrofuran showed a considerable reduction in viscosity even at room temperature when aged for a few days. Studies on this phenomenon has resulted in that this was neither due to the breaking down of associated or solvated molecules, nor alteration in the geometric configuration of the polymer chain in solution, but was due to the degradation of the polymer chain in solution. The degradation took place in the very presence of both any radical-producing substance and extremely small amount of oxygen.

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The interaction between styrene radicals and ferric ions has been investigated in nonaqueous media. Bamford et al. used N, N-dimethyl formamide (DMF) as the most suitable solvent, while in the present paper acetone was found to be a good solvent for the monomer, polymer, and salt. It seems that the ferric ion in acetone is less reactive than that obtained in DMF, on the basis of the retardation after the inhibitionof rate even in 10% conversion in the present case. Moreover, this paper is concerned with the interaction between styrene radical and several metallic salts (PbAc₄, CoAc₂, SnCl₄, MnCl₂). But no useful results have been obtained.

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Polyvinylalcohol (PVA) was oxidized by hydrogen peroxide (H₂O₂) in water. PVA is degradated markedly at 60°C, but not so at 30°C, without catalyst. In the presence of alkali catalyst, PVA is degradated markedly even at 30°C. 10-20 H₂O₂ molecules are necessary for the cleavage of one bond in the main chain. Each degradated PVA molecule has about one carboxyl group and one carbonyl group. There are no other reaction than the degradation. 1, 2 glycol bond is more easily degradated by oxidation than 1, 3 glycol bond.

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