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Volume 43, Issue 7
Displaying 1-13 of 13 articles from this issue
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Tetsuo Asakura, Hiroaki Yoshimizu, Masuhiro Tsukada, Koichi Setoyama, ...1987 Volume 43 Issue 7 Pages 335-342
Published: July 10, 1987
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSThe ESR spectra of the Bombyx mori and Philosamia cynthia ricini silk fibroins spin-labelled the tyrosine side chain groups with nitroxide compounds are observed. The activation energy of the B. mori silk fibroin in aqueous solution obtained from the plot of the rotational correlation times, τc, determined from the ESR spectra against temperature-1 is 4.46 Kcal mol-1 in the temperature range of 20_??_90°C. The activation energy is also determined as 4.55 Kcal mol-1 for P. c. ricini silk fibroin in aqueous solution in the temperature range of -5_??_40°C, while a new broad peak component (τc>10-8 s) with the activation energy, 4.05 Kcal mol-1 is observed above 50°C other than main peak component. Such a broad component corresponds to the β-structure of the silk fibroin, indicates the ease of occurrence of the β-structure in P. c. ricini silk fibroin compared with B. mori silk fibroin. For the membranes of these silk fibroins, the activation energies of the rotational orrelation time are obtained as 4.53 Kcal mol-1 (for B. mori) and 2.74 Kcal mol-1 (for P. c. ricini), indicating the thermal stability of the P. c. ricini silk fibroin membrane compared with B. mori silk one. The structures and thermal properties of these membranes are essentially unchanged by the spin-labelling treatment.View full abstractDownload PDF (1005K) -
Sumiko Hasegawa, Nobuhiko Nakano, Masao Sumita1987 Volume 43 Issue 7 Pages 343-347
Published: July 10, 1987
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSThe effect of molecular weight on the fracture of polystyrene has been analyzed by the method of linear elastic fracture mechanics.
The fracture energy per unit area or the critical energy release rate Gc, increases with increasing molecular weight, showing S mark curve with the change of molecular weight as well as the fracture strength σ and the critical stress intensity factor or the fracture toughness Kc. Namely, Gc is proportional to the square of the molecular weight in the range of low molecular weight and gets nearer to a constant value in the range of high molecular weight.View full abstractDownload PDF (282K) -
Hiroko Yoshida, Mitsuhiko Hida1987 Volume 43 Issue 7 Pages 348-353
Published: July 10, 1987
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSTaft and his co-workers proposed Linear Solvation Energy Relationships (LSER) parameters in order to quantify solvent effect: π* scale of solvent polarity, α scale of hydrogen-bond donor, and β scale of hydrogen-bond acceptor. A conventional method for evaluation of α, β, and π* scales was proposed based on spectroscopic measurements using solvatochromic indicators A, B and C. The LSER parameters of alcohols were evaluated and their relationships with the chemical structure were discussed. It was concluded that (1) π* scale is mainly controlled by the dipole-dipole interactions, (2) α scale depends mainly on the inductive effect of alkyl groups and (3) β scale is influenced by the steric effect around α-carbon.View full abstractDownload PDF (361K) -
Machiko Shimada, Yoshihiko Kawakami, Hirokazu Akabori, Yoshio Nakamura1987 Volume 43 Issue 7 Pages 354-361
Published: July 10, 1987
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSGraft copolymerization of styrene onto γ-ray irradiated cellulose was carried out with various trunk polymers; untreated cotton cellulose, mercerized cellulose, and carbamoylethylated and carboxyethylated celluloses. Then the fine structures of styrene grafted celluloses were studied by measuring moisture regain, water imbibition and degree of crystallinity under dry and wet conditions. Although hydrophilicity of untreated cellulose, carbamoylethylated and carboxyethylated cellulose in 3% sodium hydroxide solution and mercerized cellulose was not lost by grafting reaction, highly hydrophilic nature was lost by styrene grafting onto carbamoylethylated and carboxyethylated cellulose in 20% sodium hydroxide. Consequently it was confirmed that polystyrene grafts were introduced to amorphous regions in the first stage of grafting reaction, then to semicrystalline regions and finally to crystalline regions with disarranging the crystal structure. Such phenomena are the same in all samples, but the extent of grafting beyond which disarrangement of crystalline regions occurs depends on the samples. In other words, the amounts of amorphous and semicrystalline regions in the samples determine the behavior of grafting.View full abstractDownload PDF (511K) -
Akira Takahashi, Yasusato Sugahara, Yoshiteru Horikawa1987 Volume 43 Issue 7 Pages 362-369
Published: July 10, 1987
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSThe graft copolymerization of methyl methacrylate onto chitosan was carried out, and the following results were obtained.
1) In the case of the non-catalytic photo-induced method, an induction period was observed and the polymerization proceeded mainly by the photolysis of amino groups.
2) In case of the photosensitized method, the grafting activity of azobisisobutylonitrile was higher than that of ph2 CO.
3) In the initiator method, the grafting activity of ammonium persulfate was higher than that of H2O2.
The degree of grafting and the apparent number of grafted chains generally decreased in the following order; the initiator method>the photo-induced method without catalyst>the photoinduced method with photosensitizer.
As for the photo-induced graft copolymerization of binary monomers (AN-MMA and AN-St) in the presence of chirosan, the monomer reactivity ratios of the graft and the ungrafted copolymer almost coincided with the values of the literature obtained in homogeneous system.View full abstractDownload PDF (450K) -
Michihiko Tanaka, Shunji Nakazawa1987 Volume 43 Issue 7 Pages 370-375
Published: July 10, 1987
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSThermal decomposition of poly (1, 4-butyleneterephthalate) (PBT) was investigated in open and closed systems. The activation energies for the thermal decomposition of PBT in closed and open systems were 41.5 and 38.0kcal/mol, respectively, showing that the decomposition behavior is almost the same for both systems.
Hydrolysis behavior of PBT was also studied in neutral and alkaline solutions, and compared with that of poly (ethyleneterephthalate) (PET). The results on the hydrolysis in neutral solutions showed that (1) the hydrolysis of both polyesters is a solid-liquid reaction, but can be treated as random scission of the ester linkages in the main chain, and (2) the activation energy of 21 kcal/mol, obtained for the hydrolysis of PBT is slightly lower than that of PET (27kcal/mol). Concerning the alkaline hydrolysis, it was found that (1) the weight loss of PBT is smaller than that of PET, and (2) the molecular weights of residual polymers were almost the same as those of the starting polyesters.View full abstractDownload PDF (393K) -
Kiyohisa Takahashi, Yuhji Kon, Tadashi Yano, Tsu-Wei Chou1987 Volume 43 Issue 7 Pages 376-383
Published: July 10, 1987
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSThe effect of fiber waviness on the elastic moduli of unidirectional fiber composites was investigated theoretically. All fibers are assumed to be laid parallel to each other and have a sinusoidal curvature. A few geometric relations were derived among the wave length, the amplitude and the fiber length of a sinusoidal shaped fiber. Then, linear elastic constitutive equations were established for two kinds of fiber arrangements: (1) the iso-phase model, and (2) the random-phase model. Finally, the Young's moduli in longitudinal and transverse directions were examined by numerical examples.View full abstractDownload PDF (440K) -
Tomiji Wakida, Haruo Kawamura, Jin Cherl Song, Tokuju Goto, Toru Takag ...1987 Volume 43 Issue 7 Pages 384-390
Published: July 10, 1987
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSPoly (ethylene terephthalate) (PET) and nylon 6 films were treated with low temperature plasma in various gases, oxygen, nitrogen, hydrogen, helium, argon, methane, tetrafluoromethane, trifluoromethane, monochlorotrifluoromethane, and tetramethylsilane. The contact angles of various liquids of different surface tensions on the plasma-treated films were measured. The lowest surface tension γc (Zisman) and the highest surface tension γc (max) of the polymers were determined on the basis of the Zisman plots. Furthermore, the contributions of nonpolar dispersion, dipole, and hydrogen bonding forces to the surface tensions for the plasma-modified polymers were evaluated by the extended Fowkes equation. In addition, the plasma-treated samples were characterized by X-ray photoelectron spectroscopy (ESCA). The change in surface free energy of the plasma-treated films was correlated with their surface chemical compositions measured by ESCA.View full abstractDownload PDF (406K) -
ISAMU TATSUMI1987 Volume 43 Issue 7 Pages P244-P249
Published: July 10, 1987
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSDownload PDF (2300K) -
TANIGAWA JUNICHI1987 Volume 43 Issue 7 Pages P250-P255
Published: July 10, 1987
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSDownload PDF (1162K) -
NOBUYA YOSHIMURA1987 Volume 43 Issue 7 Pages P256-P262
Published: July 10, 1987
Released on J-STAGE: November 28, 2008
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YOSHIKAZU KADOYA, NORIO YOSHIDA1987 Volume 43 Issue 7 Pages P263-P269
Published: July 10, 1987
Released on J-STAGE: November 28, 2008
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MITSUO SAKANIWA1987 Volume 43 Issue 7 Pages P270-P276
Published: July 10, 1987
Released on J-STAGE: November 28, 2008
JOURNAL FREE ACCESSDownload PDF (1051K)
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