Kobunshi Kagaku
Online ISSN : 1884-8079
Print ISSN : 0023-2556
ISSN-L : 0023-2556
Volume 16, Issue 172
Displaying 1-10 of 10 articles from this issue
  • I. Newtonian Viscosity and Dependence on Stress
    Masao Takahashi
    1959 Volume 16 Issue 172 Pages 475-478
    Published: August 25, 1959
    Released on J-STAGE: October 14, 2010
    JOURNAL FREE ACCESS
    The relationships between shear stress and flow rate for the low pressure polyethylene were measured by a capillary viscometer. Two Hizex polyethylene samples, made by Ziegler process, having number-average molecular weights of 40, 000 and 61, 000, were investigated under the following experimental conditions; shear stress range 105-106 dyne⋅cm-2; temperature range 180-340°C; diameter and length of the capillary 0.5 mm and 1mm, respectively. The rate of shear increases with shear stress more rapidly than would be expected from thedirect proportionality for the Newtonian liquid. The zero-shear viscosities ηo obtained by extrapolation to zero shear stress were found to be fairly large. Though ηa showed thesmaller value for the lower molecular weight and became smaller with temperature, η0 of the sample having molecular weight of 40, 000 was 2, 700 poise at 280°C. The apparent activation energy for viscous flow was 6-8 kcal/mol in the range of experimental conditions. The flow curves were well represented by the so-called power law for the flow curve; D=aτwN. The value of the exponent N were the smaller one for the smaller molecular weight, decreased with increasing temperature and lay between 2.0 and 2.4 under the experimentalconditions.
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  • II. The Flow Properties of Various Low Pressure Polyethylenes
    Masao Takahashi
    1959 Volume 16 Issue 172 Pages 478-483
    Published: August 25, 1959
    Released on J-STAGE: October 14, 2010
    JOURNAL FREE ACCESS
    The flow properties of nine samples of low pressure polyethylene (Hizex A, B, C and D, Marlex 50, Hostalen GD, GF, GM and Hifax) and two samples of high pressure polyethylene (Tenite and Dow Chemical Polyethylene) were investigated. The experiments were carried out using a capillary viscometer. The relationship between Mν, and initial viscosity η0 for the low pressure polyethylene Hizex ranging in number-average molecular weight from 16, 500 to 155, 000 and in melt viscosity η0 from 3×102 to 4×105 poises can be expressed numerically by the following equations: logη0=3.1logMν-10.7 (200°C) logη0=3.1logMν-11.0 (240°C) The low pressure polyethylene generally has smaller activation energy for viscous flow than the high pressure polyethylene. When the values of exponent N (in D=aτwN) are plotted as a function of the logη0 for these polyethylenes, fairly good linear relations are obtained. The fact that even though Marlex 50 has fairly large A, it has much smaller η0 and N than the other low pressure polyethylenes is one of the characteristics of Marlex 50 polyethylene.
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  • Film Formation of Synthetic Resin Latices
    Mitsuo Fujii, Yasuji Ohtsuka
    1959 Volume 16 Issue 172 Pages 484-490
    Published: August 25, 1959
    Released on J-STAGE: October 14, 2010
    JOURNAL FREE ACCESS
    The surface and internal structures of films prepared from polybutyl methacrylate latex were observed under an electron micro-scope, and the mechanical properties of films were measured. Elevation of drying temp. or heat treatment (120°C, 5 min.) were favorable toformation of perfect films in which coalescence of polymer particles was complete. Effects of amount of potassium persulfate and emulsifier to the film-forming temp. Tf, particle diameter d, and intrinsic viscosity [η] of methyl methacrylate-methyl acrylate copolymer latex were investigated. The decrese in Tf with decrease in d and in [η] was discussed theoretically.
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  • II. Crystallinity measured by X-Ray Diffraction Method
    Yoshio Tsunoda, Itsuho Aishima, Kenichi Katayama
    1959 Volume 16 Issue 172 Pages 491-494
    Published: August 25, 1959
    Released on J-STAGE: October 14, 2010
    JOURNAL FREE ACCESS
    In the previous paper, the crystallinity of Saran filament was calculated from density measurements. This paper reports on crystallinity calculations from X-ray diffraction measurements. In the X-ray diffraction pattern of Saran filaments, it is impossible to distinguish precisely the crystalline part from the amorphous part, so a simple method was used. To avoid any error due to the orientation of the filament, finely cut samples are placed at random position perpendicular to the X-ray beam and the field rotated. The crystallinity of non-heat-treated filamentsi s 25.4%w hich increases up to 30.6% by stretching to maximum stretch ratio under heat-treatment. The crystallinity has a tendency to increase slowly with the increase of stretch ratio, but increases rapidly with the increase of temperature of the cooling bath. Therefore, the results measured by density method and X-ray method agree in that the crystallinity changes with changes of the conditions of the extrusion and heat-treatment.
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  • I. Influence of Crystallization Temperature
    Yoshio Tsunoda, Itsuho Aishima, Hisaya Sakurai, Hideo Fusauchi
    1959 Volume 16 Issue 172 Pages 495-498
    Published: August 25, 1959
    Released on J-STAGE: December 22, 2010
    JOURNAL FREE ACCESS
    In the extrusion of Saran, the crystallization-rate of molten polymer is controlled by extrusion conditions. The influence of temperature on the crystallization-rate, as measured by the density gradient tube method, is discussed. The crystallization-rate constant, k, decreases with the lowering of the temperature. The induction period of crystallization ττichanges with the temperature. The temperature at which the induction period is less than one second is estimated to be about 80-90°C This value agrees with the temperature reported by R. Boyer. In the relation between log ττiand 1/T, a break point was found at about 15°C and at the temperature below this point, ττi increases rapidly. This point agrees with the second-order transition point of Saran. However, in the relation between the specific volume of amorphous polymer and the temperature, the second-order transition point was not confirmed.
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  • Kiyokazu Imai, Unpei Maeda
    1959 Volume 16 Issue 172 Pages 499-504
    Published: August 25, 1959
    Released on J-STAGE: October 14, 2010
    JOURNAL FREE ACCESS
    The turbidity velocity of the aqueous dimethyl sulfoxide solutions (4000, water) of PVA was measured on some samples polymerized in several solvents, at several temperatures, or copolymerized with a few comonomers. It was observed that the greater was the turbidity velocity, the less was the degree of swelling of the PVA films in water.
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  • A Comparison of the Emulsion Polymerization of Methyl Methacrylate in the Layer System and in the Agitated System
    Yasuji Ohtsuka
    1959 Volume 16 Issue 172 Pages 505-508
    Published: August 25, 1959
    Released on J-STAGE: October 14, 2010
    JOURNAL FREE ACCESS
    Methyl methacrylate polymer was prepared by emulsion polymerization in both layer system (L) and agitated system (A). The rate of conversion and the molecular weight of the polymer in L were extremely lower than in A, and the number of polymer particle in L was greater than in A. These phenomena were discussed from the difference of the rate of monomer supply to polymer particle between L and A.
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  • II. Influence of the Plasticizer Added in the Layer Polymerization of Methyl Methacrylate to the Rate of Conversion
    Yasuji Ohtsuka
    1959 Volume 16 Issue 172 Pages 509-515
    Published: August 25, 1959
    Released on J-STAGE: October 14, 2010
    JOURNAL FREE ACCESS
    The mix of methyl methacrylate and DBP was polymerized in the layer system. It was shown that there were three types of conversion-DBPc urves for any given time duration: in M type the rate of conversion increased with increase of the amount of DBP to a certain point and then slowed down, in H type the rate of conversion was slightly dependent on the amount of DBP and in D type addition of DBP decreased the rate of conversion. The concentration of DBP in polymer particle was extremely lower than in methyl methacrylate- DBP oil phase. When DOP was added instead of DBP, the conversion-DOP curve was D type and DOP was not contained appreciably in polymer particle.
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  • II. Polymerization of Vinyl Acetate by Dialkylcadmium
    Kiyoshi Fujii, Tamotsu Eguchi, Junji Ukida, Masakazu Matsumoto
    1959 Volume 16 Issue 172 Pages 516-519
    Published: August 25, 1959
    Released on J-STAGE: December 22, 2010
    JOURNAL FREE ACCESS
    The polymerization of vinyl acetate (VAc) catalysed by dimethylcadmium was carried out. Dimethylcadmium was also used as catalyst. The polymerization was accelerated by the presence of oxygen. Owing to mild reactivity, organocadmium compounds were rather less effective to VAc polymerization than organoboron compounds. In the presence of oxygen, thedegree of polymerization as well as the degree of conversion was increased, compared withthose obtained under nitrogen. The polymerization initiated by dimethylcadmium could be carried out at 0deg;C. But the polymerization using a large amount of the calalyst at the elevated temperature (60°C) was markedly disturbed by the occurrence of the reaction between dimethylcadmium and VAc. The white precipitate obtained by the reaction between dimethylcadmium and VAc initiated polymerization of VAc.
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  • III. Polymerization of Vinyl Acetate by Trialkylboron
    Kiyoshi Fujii, Tamotsu Eguchi, Junji Ukida, Masakazu Matsumoto
    1959 Volume 16 Issue 172 Pages 519-522
    Published: August 25, 1959
    Released on J-STAGE: December 22, 2010
    JOURNAL FREE ACCESS
    The polymerization initiated by triethylboron was examined. Oxygen had a remarkable promoting action on the triethylboron catalysed polymerization. And also, the polymerization was accelerated by the presence of small amounts of water and methanol. In the case using the large amount of the catalyst, the degree of polymerization was remarkably decreased. From the determination of carboxyl group containing in PVA, it was suggested that the chain transfer to the catalyst took place. The physical properties of PVA, for example, the degree of swelling, the amount of 1, 2-glycol, are similar to those of PVA obtained from the usual radical polymerization. From the above results, it seems likely that the polymerization by using triethylboron is induced by a radical mechanism.
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