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Volume 50, Issue 1
Displaying 1-8 of 8 articles from this issue
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Yasunori TARU, Koichi KOBAYASHI, Masahisa TAKASAGO, Kyo TAKAOKA1993 Volume 50 Issue 1 Pages 1-9
Published: January 25, 1993
Released on J-STAGE: November 22, 2010
JOURNAL FREE ACCESSWhen poly (4-methyl-l-pentene) (PMP) and polystyrene (PS) films, which had been treated by a CF4 plasma discharge, are immersed in water, hydrophobic groups (-CF1, -CF2, -CF3) at the surface are reversed into an inert region. The dynamic characterization of the film surface was studied with respect to the contact angle of water and XPS spectra. When the treated film was immersed in water, the hydrophobic groups located up to 15Å from the surface, were reverted; they then migrated to an inert region beginning 15-30Å below the surface. These groups, then diffused into the inert region of the film, and could not be detected by XPS. Movement of the hydrophobic group was influenced by the segmental motion of the bulk molecule. This phenomenon was very vigorous above the glass transition temperature (Tg) . The diffusion rate of the hydrophobic group immersed in water at a below Tg differs from polymer to polymer. The diffusion coefficient of CF4-PMP is higher that of CF4-PS. The activation energies for the diffusion of the hydrophobic groups were 6 and 12 kcal/mol for CF4-PMP and CF4-PS, respectively.View full abstractDownload PDF (1480K) -
Tatsundo TANAKA, Takamichi YAMAKAWA, Naotake KASHIWAGURA, Toshihide IN ...1993 Volume 50 Issue 1 Pages 11-17
Published: January 25, 1993
Released on J-STAGE: November 22, 2010
JOURNAL FREE ACCESSUltra-high modulus rods were fabricated from wholly-aromatic copolyesters containing, t-butylhydroquinone (t-Bu-HQ), 4, 4'-diphenyldicarboxylic acid (BB), and p-hydroxybenzonic acid (HBA), and the properties and structures were investigated. The drawn rods were prepared by extensionally drawing from a die of 7mm diameter. The structrures of rods having 60mol%, 50mol%, 40 mol%, and 30mol% HBA were investigated by wide-angle X-ray diffraction (WAXS) and scanning electron microscopy. Two kinds of crystals were observed by WAXS. One kind of crystals contained the polymer chains of poly (p-oxybenzoate) and the other contained the polymer chains of poly (t-butyl 1, 4-phenylene-4, 4'-diphenyldicarboxylate). It was found that the higher stretching modulus (Es) was obtained for the rods containing a larger crystalline size of poly (t-butyl 1, 4-phenylene-4, 4'-diphenyldicarboxylate). Es and degree of crystalline orientation (π) of the surface layers and the center portions were measured within the drawn rods at a low extensional drawn ratio. The difference in Es and π between the surfaces and center portion of drawn rods was almost negligible. The rods of wholly-aromatic copolyester having 50mol% HBA and 50mol% t-Bu-HQ/BB yielded ultrahigh bending modulus of 91GPa for 1.0mm rod diameter and of 54GPa for 3.0mm rod diameter. Es of drawn rods decreased gradually with temperature upto 180°C. Even at 150°C, however, Es of rods remaind high level of 50 GPa.View full abstractDownload PDF (1518K) -
Takao NOMURA, Takeyoshi NISHIO, Hiroki SATO, Hironari SANO1993 Volume 50 Issue 1 Pages 19-25
Published: January 25, 1993
Released on J-STAGE: November 22, 2010
JOURNAL FREE ACCESSA blend of impact-resistant poly (propylene-ethylene) copolymer and 20-30wt% of ethylene-propylene rubber (EPR) is widely used in the outer parts of automobiles. The properties of the material can not be fully explained on the basis of the generally accepted morphological model of polypropylene (PP) matrix and EPR domains. In this report, a morphological model composed of PP crystaline lamella domains distributed in a matrix consisting of networked amorphous PP and EPR is proposed, based on the detailed investigation by transmission electron microscopy (TEM), and visco-elastic and pulsed NMR measurements. This new morphological model reasonably explains several phenomena, such as the constancy of the impact strength and the elongation at break measured as a function of molecular weight of PP and the discontinuity in the Rockwell hardness and heat sag observed as a function of EPR content.View full abstractDownload PDF (2974K) -
Takao NOMURA, Takeyoshi NISHIO, Hiroki SATO, Hironari SANO1993 Volume 50 Issue 1 Pages 27-34
Published: January 25, 1993
Released on J-STAGE: November 22, 2010
JOURNAL FREE ACCESSIn blends of impact-resistant poly (propylene-ethylene) copolymers and 20-30wt% of ethylene-propylene rubber (EPR), the matrix consists of elastomers. We could improve the mechanical properties of the blends by introducing a hard segment in the matrix. An ethylene-based copolymer with some degree of crystallinity was added to the blends in order to be dispersed like IPN crystalline lamella in the EPR phase. Thus, a marked improvement was observed in the hardness and modulus. Such a phenomenon is discussed on the basis of a mechanical model and a finite element method. Further, it was found that the dynamic hardness was related to the amounts of crystalline, intermediate and amophous components determined by pulse-NMR.View full abstractDownload PDF (2710K) -
Masashi BEPPU, Teruhiko BABA, Chiyoshi KAMIZAWA1993 Volume 50 Issue 1 Pages 35-40
Published: January 25, 1993
Released on J-STAGE: November 22, 2010
JOURNAL FREE ACCESSChitosan membranes for ultrafiltration were prepared by the phase inversion method with an aqueous solution of acetic acid as the solvent. In order to improve the membrane performance, various organic solvents were employed as the gelating agents. Their effects on the membrane formability and performance were investigated from the viewpoint of their behaviors in gelating processes. The gelating agents showing good membrane formability could be grouped into two groups depending on the heat change obtained by mixing chitosan solution and gelating agent. The agents showing endothermic change in the case of mixing formed tight membranes and the agents showing exothermic change formed loose membranes. Further, the agents having the higher fluidity formed the looser membranes among the exothermic gelating agents. These results suggest that the affinity for water of the gelating agent as well as the relative exchange ratesbetween water in chitosan-rich phase and the gelating agent play important roles as determinants for the membrane performance.View full abstractDownload PDF (1371K) -
Keiji MAEDA, Yasuo YUKI1993 Volume 50 Issue 1 Pages 41-47
Published: January 25, 1993
Released on J-STAGE: November 22, 2010
JOURNAL FREE ACCESSPoly (methyl methacrylate-co-methacrylic acid) -graft-polysiloxanes (PMAA-g-PDMSs) were prepared by radical copolymerization of methyl methacrylate (MMA), methacrylic acid (MAA), and silicone macromonomer (Si-MM). PMAA-g-PDMSs were treated with aqueous sodium hydroxide solution to give poly (methyl methacrylate-co-sodium methacrylate) -graft-polysiloxanes (PMAANa-g-PDMSs). Surface properties of coating films of copolymers having silicone branches (Mn=1000, 10000) were evaluated in terms of contact angle and dynamic coefficient of friction. From contact angle toward droplets of each solvent, the critical surface tensions (γc) were estimated by extrapolation to cos θ=1 and the solid surface tensions (γs) were evaluated by the extended Fowkes'equation. γcs were decreased from 32 dyn/cm to 22-24dyn/cm by the introduction of silicone segments. γs also decreased by the introduction of silicone segments; the values of each component (γsa, γsb, andγsc) were changed. The dynamic coefficient of friction decreased with neutralization of PMAA-g-PDMSs.View full abstractDownload PDF (1077K) -
Hiroko MAEDA, Masao SUZUKI, Hajime SHOHI, Kenichi ASAHINA1993 Volume 50 Issue 1 Pages 49-56
Published: January 25, 1993
Released on J-STAGE: November 22, 2010
JOURNAL FREE ACCESSReversibility of acetalization of poly (vinyl alcohol) with butyraldehyde and syntheses of a series of poly (vinyl butyral) s with high acetalization degrees were examind. The reaction was carried out sequentially by the dissolution and precipitation method. The degree of butyralization in polymer was determined by titration, IR, and elemental analysis. The highest degree was 91mol%, which suggests that the acetalization is reversible.View full abstractDownload PDF (1262K) -
Akio TAKAHASHI, Akira NAGAI, Masao SUZUKI, Akio MUKOH1993 Volume 50 Issue 1 Pages 57-63
Published: January 25, 1993
Released on J-STAGE: November 22, 2010
JOURNAL FREE ACCESSThe curing mechanism of a maleimide-styryl (MS) resin, which was prepared by the reaction of poly (bromo-4-vinyl phenyl methacrylate) (PVPM), 2, 2-bis [4- (4-maleimide phenoxy) phenyl ] propane (BBMI), and epoxy-modified polybutadiene (EPB), was investigated by differential scanning calorimetry (DSC). The curing reaction of the MS resin with 2, 5-dimethy1-2, 5-di (t-butyl peroxy) -3-hexine (25B) and benzoguanamine (BG) as hardeners was found to take place by radical polymerization of the double bonds in PVPM, BBMI, and EPB with 25B at about 140°C to 170°C followed by addition of the amino group of BG to the maleimide group of BBMI and the epoxy group of EPB at 210°C This curing reaction proceeded at lower temperature with dicyanodiamide (Dicy) instead of BG as a hardener. Addition reaction of Dicy to BBMI and EPB was completed below 190°C.View full abstractDownload PDF (969K)
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