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Volume 52, Issue 3
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Shinichiro NAGAI, Masaru ISHIKAWA1995 Volume 52 Issue 3 Pages 125-133
Published: March 25, 1995
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSMechanism of the fatigue fracture of polypropylene (PP) has been investigated by both the uniaxial tensile fatigue test in which the state of stress is close to the pure shear stress state without expansion of specimen and the three point bending fatigue test of round notched bars in which the stress state is close to the dilatational stress state. The modes of fatigue fracture depended on the stress state corresponding to the fracture mode of the ductile polymer during the steady increase of load. The mode of fatigue fracture was necking fracture in the uniaxial tensile fatigue test and brittle fracture in the three point bending fatigue test. It was concluded that the increase of temperature caused by viscoelastic energy loss seriously affected the fatigue fracture in the uniaxial tensile fatigue test, and the failure of fibrils was a dominant factor for the fatigue fracture in the dilatational stress state due to the notches.View full abstractDownload PDF (6839K) -
Masaru ICHIKAWA, Masataka SUGIMOTO, Koichi HATADA, Tadashi TANAKA1995 Volume 52 Issue 3 Pages 134-140
Published: March 25, 1995
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSEffect of tacticity on the toughness of polypropylene (PP) has been experimentally studied. High tacticity PP exhibited a tendency to stiffen due to high crystallinity, and furthermore the toughness was significantly improved with increasing strength of the fibrils extending across the craze, compared with that of conventional PP. The number of regular folds of melt-crystallized PP estimated with the Kringbaum model increased with increasing tacticity. It is assumed that the drop in the number of stereo irregularities preceded crystallization from the melt, resulting in high stiffness and high toughness of high tacticity PP.View full abstractDownload PDF (2860K) -
Masaru ICHIKAWA, Yuji KOBAYASHI1995 Volume 52 Issue 3 Pages 141-148
Published: March 25, 1995
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSCrazing of poly (butylene terephthalate) (PBT) has been studied by three point bending of round-notched bars under plane strain state in comparison with that of polyamide-66 (PA-66). The plastic deformation of PA-66 varied from unstable plastic deformation (craze) to stable plastic deformation (microcraze) as the temperature increased. On the other hand, the plastic deformation of PBT was unstably deformed over the examined temperatue (293-420 K). This difference in plastic deformation was discussed on the basis of the theory of plastic instability. It was concluded that instability of plastic deformation of PBT was caused by an increase in the ratio of the yield stress to the shear elastic modulus with increasing temperature.View full abstractDownload PDF (6156K) -
Masaru ICHIKAWA, Masataka SUGIMOTO, Koichi HATADA, Tadashi TANAKA1995 Volume 52 Issue 3 Pages 149-154
Published: March 25, 1995
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSEffect of the width of molecular weight distribution on the toughness of polypropylene (PP) has been experimentally studied. The samples of different molecular weight distribution were prepared by the controling process of polymerization at a constant tacticity and by scission of the polymer chain with a peroxide. The effect of the width of molecular weight distribution on toughness was tested by the three-point bending of U-notched bars. The toughness increased with the decrease of the width of molecular weight distribution in either case, although its effect depends more on the number average molecular weight rather than on the width of molecular weight distribution.View full abstractDownload PDF (4934K) -
Shuji SAKOHARA, Teruyuki KOSHI, Masashi ASAEDA1995 Volume 52 Issue 3 Pages 155-162
Published: March 25, 1995
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSDimethylaminoethyl methacrylate gels were synthesized by crosslinking with ethylene glycol dimethacrylate (EGDMA), diethylene glycol dimethacrylate (DEGDMA), or triethylene glycol dimethacrylate (TEGDMA). They swell in aromatic solvents but hardly at all in paraffinic solvents. The gels were formed in the pores of thin silica membranes. The composite membranes were used for separation of benzene/cyclohexane mixtures by the pervaporation method. As expected from the swelling-shrinking behavior of the gels in benzene/cyclohexane mixtures, benzene permeated selectively through the membranes. The selectivity depended on the length of the crosslinking agents used for synthesizing the gels, and increased in this order: EGDMA>TEGDMA>DEGDMA. Furthermore, the swelling-shrinking behavior in benzene/cyclohexane mixtures depended on tempcrature, because of the heat-sensitive property of gels, and even in cyclohexane, the swelling of gels was clearly noticed with increasing temperature. Thus the selectivity of composite membranes lowered with increasing the separation temperature.View full abstractDownload PDF (1536K) -
Kazuhide MORI, Tutomu ARAKAWA, Keiko TAMURA, Yoshihiro SHIBUSA1995 Volume 52 Issue 3 Pages 163-168
Published: March 25, 1995
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSThe Monte Carlo method was applied to predict the chlorine distribution in chlorinated polyethylene. Mutual interaction coefficients between chlorines were determined from molecular orbital calculations. Effective parameters to account for the synthetic condition were experimentally obtained from NMR measurements. Since the simulation results for chlorine distribution are in good agreement with NMR experiments, we conclude that the approach is a useful method to evaluate the correlation between reactivity and structure. Furthermore, it can also be applied to different substitution and adsorption reactions.View full abstractDownload PDF (992K) -
Tatsuo NAKAMURA, Yoshihiko KONDO, Noriko SUZUKI, Masanao TANAKA, Hiroa ...1995 Volume 52 Issue 3 Pages 169-173
Published: March 25, 1995
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSAmmonia gas adsorption characteristics of various polymer-iron chloride complexes have been investigated. Among them poly (vinyl alcohol) -FeCl3 chelate showed an excellent ammonia gas adsorption rate and amount of saturated adsorption compared with other polymer-metal chelates deodorizers on the market.View full abstractDownload PDF (780K) -
Koichi KITAO, Hidekazu TURUTA1995 Volume 52 Issue 3 Pages 174-180
Published: March 25, 1995
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSThe relation between rapid crack propagation and crystallinity of a variety of polyethylenes (used for excluding pipes) has been investigated. The fracture toughness of polyethylenes with different crystallinities, such as linear low density polyethylene (LLDPE), medium density polyethylene (MDPE), and high density polyethylene (HDPE), was evaluated by the Charpy impact test. The value of the absorbed energy at -20°C, a parameter for low temperature toughness, increased with the crystallinity, accordingly the density of the polyethylene. On the other hand, the value of the absorbed energy at 20°C, a parameter for the toughness at ambient temperature, decreased with the crystallinity of the polyethylene and increased with the intensity of β relaxation.View full abstractDownload PDF (3113K) -
Koichi KITAO, Hidekazu TURUTA1995 Volume 52 Issue 3 Pages 181-186
Published: March 25, 1995
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSThe relation between rapid crack propagation and morphology of a variety of polyethylenes (used for excluding pipes) has been investigated. The fracture toughness of polyethylenes such as linear low density polyethylene (LLDPE), medium density polyethylene (MDPE), and high density polyethylene (HDPE) annealed under various conditions was evaluated by the Charpy impact test. The relaxation behavior of polyethylene was affected by annealing, and the absorbed energy at 20°C was dependent on the intensity of β relaxation rather than the crystallinity of the resin. The sample quenched after annealing showed smaller β relaxation intensity and smaller absorbed energy at 20°C, compared with the samples cooled slowly after annealing.View full abstractDownload PDF (952K) -
Takeshi YAMAMOTO, Hiroaki FURUKAWA1995 Volume 52 Issue 3 Pages 187-193
Published: March 25, 1995
Released on J-STAGE: March 15, 2010
JOURNAL FREE ACCESSFor amorphous glassy polymers, their shear yield stresses and crazing stresses were represented by molecular parameters, which are related to chain flexibility, interchain effect and effective volume for shear yield stress, void formation and fibrillation stress for crazing stress, respectively. These molecular parameters were satisfactorily calculated by group contribution method, which is a semi-empirical method for predicting the properties of polymers by summing parameters assigned to either atoms, groups or bonds. By using these calculated molecular parameters, shear yield stress and crazing stress were predicted for glassy polymers. The predicted values were in good agreement with the ones measured at various temperatures including room temperature, and therefore the present method is useful to predict their temperature dependences.View full abstractDownload PDF (1152K)
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