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Volume 33, Issue 12
Displaying 1-7 of 7 articles from this issue
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Masayoshi URABE, Kiyohisa IMADA1976 Volume 33 Issue 12 Pages 697-702
Published: December 25, 1976
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSAfter isothermal crystallization of unfractionated polyethylene in dilute solution, discontinuous thinner borders precipitate around growth edges of original lamellae of single crystals depending on temperatures of crystallization which occurs during slow cooling after the end of isothermal crystallization process. The molecular chains in these thinner borders refold thermodynamically in the same thicknesses of the original lamellae. The refolding of thinner borders was observed by electron microscopy on the crystallization of polyethylene single crystals in solution, annealing in solvent or under high vacuum.View full abstractDownload PDF (2804K) -
Tomoyuki KASEMURA, Norio YAMASHITA, Takashi KONDO, Toshio HATA1976 Volume 33 Issue 12 Pages 703-709
Published: December 25, 1976
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSDialkyl phthalates are extensively used for plasticizer of polymer, and it is important to investigate the surface chemical properties of these materials. We measured the surface tension of dialkyl phthalates of various chain lengths with the sessile bubble method and the contact angle to the paraffin. The surface tension (γL) and the surface energy (ES) of dialkyl phthalates decreased with the increase of molecular weight (M) as high as M=418 where they reached minimum values. The surface entropy (SS) decreased with the increase of M and approached the value of polyethylene. The components of surface tension due to dispersion force and polar force were calculated by Fowkes' equation from contact angle data. The component due to dispersion force (γLa) showed a constant value up to M=250. In a range of M>250, γLa varies in accord with the surface tension of n-alkane which have two times molecular weight of alkyl group. On the other hand, the component due to polar force (γLb) initially decreased drastically with M and approached a constant value over M=300. These results can be explained neither by Gaines' formura nor by Hata's.View full abstractDownload PDF (1181K) -
Effects of γ-Irradiation and Post-irradiation Extraction on the Surface Morphology of Nylon 6 FibersYasuharu FUJIWARA, Saiko KOBAYASHI1976 Volume 33 Issue 12 Pages 711-716
Published: December 25, 1976
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSA study has been made of the morphological changes of nylon 6 on the fiber skin layer caused by γ-ray irradiation of 30 and 40 Mrads in air at room temperature. By the extraction with water at 70°C, weight of the fiber decreased and cracks identical in breadth and depth appeared on the surface in the direction perpendicular to the fiber axis. As the cracks propagated, the skin layer contracted along the fiber axis and the crystallinity increased in the layer. The skin layers having such cracks were easily separated from the core layers. The morphological changes can be explained in terms of the differences of the skin and core structures in response to the both irradiation of γ-rays and extraction with water.View full abstractDownload PDF (2305K) -
Hiroshi UENO, Shinya OTSUKA1976 Volume 33 Issue 12 Pages 717-721
Published: December 25, 1976
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSThe measurement of bulk viscosity (η) and local viscosity (ξ) for narrow molecular weight distribution polystyrene was carried out at temperatures between 50°and 230°C. The molecular weights of the five samples used ranged from 600 to 390, 000. η was determined by the use of capillary viscometer depending on the viscosity of sample, while ξ by the fluorescence depolarization method. (1) The temperature dependence of η followed very well the WLF equation; (2) the temperature dependence of ξ showed an upward concave curvature in high temperature region, but with decreasing temperature approached a constant value; and (3) the molecular weight dependences of η and ξ became distinctly different in the molecular weight range exceeding 104. The tentative explanation for such findings was given in terms of the entanglement concept.View full abstractDownload PDF (870K) -
Hiroshi UENO, Shinya OTSUKA1976 Volume 33 Issue 12 Pages 723-731
Published: December 25, 1976
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSThe measurements of bulk viscosity (ηb) and local viscosity (ζb) for the samples blended with two narrow molecular weight distribution polystyrenes, 600 and 37, 000, were carried out at 50°-230°C. ηb and ξb were determined by use of capillary visometer and fluorescence depolarization, respectively. (1) The temperature and concentration dependences of ηb fitted very well the tree volume (f) theory; (2) the plot, log ζb vs. reciprocal of f obtained from the temperature dependence of ηb, gave an convex curve; (3) the curves of weight average molecular weight (Mw) vs. ηb and ζb gave concave curves; (4) when ηb was plotted against Mw under the iso-free-volume state, two straight lines were obtained with a break at Mw=1.78×104 and the slopes of 1.0 and 3.3, respectively; and (5) ζb was proportional to Mw under the iso-free-volume condition.View full abstractDownload PDF (1473K) -
Kuniyoshi ITOYAMA, Michio KASHIWAGI1976 Volume 33 Issue 12 Pages 733-739
Published: December 25, 1976
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSFrom the analysis of the angular and temperature dependences of the second moment in the NMR spectra of uniaxially drawn Nylon 6 and 12 films, the following results have been obtained. 1) Estimated values of orientation parameters P2 (cos Δ) and P4 (cos Δ) for a Nylon 6 film drawn 6.0 times are shown to be different from those derived from a pseudo-affine deformation model. 2) The angular dependence of the second moment for Nylon 6 (D.R. 6.0) at 170°C is consistent with that obtained from a model for the molecular motion, in which the CH2 groups adjacent to the NH or CO groups in the molecule stay at rest and the other CH2 groups rotate freely around the molecular axis. 3) In the oriented regions which give broad components in the NMR spectra of Nylon 6, a transition related to molecular motions such as rotation or oscillation around the molecular axis takes place at 110-130°C. In the case of Nylon 12, the transitions of almost isotropic motion in the rigid regions are observed at about 20° and 125°C.View full abstractDownload PDF (1253K) -
Kuniyoshi ITOYAMA1976 Volume 33 Issue 12 Pages 741-748
Published: December 25, 1976
Released on J-STAGE: February 26, 2010
JOURNAL FREE ACCESSBroad line NMR measurements have been made on the variously treated yarns of Nylon 6 and Poly (ethylene terephthalate) (I), to investigate the change of the internal structure with drawing and annealing. Annealing an undrawn Nylon 6 yarn keeps the amount of the mobile part unchanged. An estimated value of the potential barrier height in the amorphous regions from temperature dependence of the amount of the mobile part, is 12.1kcal/mol at temperatures below about 150°C, and 2.9kcal/mol above 150°C, and annealing the yarn under relaxed state does not change these values. Annealing a drawn I yarn under relaxed state decreases the amount of the rigid part and increases its rigidity, but under fixed state gives only a little change in the amount and rigidity of the rigid part. The NMR behavior of I yarns with drawing and annealing is explainable in terms of Stattons' model proposed for Nylon 66 yarn.View full abstractDownload PDF (1441K)
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