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Predecessor
Volume 75, Issue 11
Displaying 1-6 of 6 articles from this issue
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Eiichi KAWAI, Hee Cheong LEE, Yuusuke TAKAO, Kenji OGINO, Hisaya SATO2002 Volume 75 Issue 11 Pages 465-468
Published: 2002
Released on J-STAGE: May 28, 2007
JOURNAL FREE ACCESSCopolymers of butyl acrylate (BA) and ethyl acrylate (EA) were prepared. Their conversion was kept below 10% for obtaining samples with a narrow chemical composition distribution. The composition of each sample was determined by 1H nuclear magnetic resonance (NMR). The mixture of the copolymers was separated depending on composition by normal and reversed phase high performance liquid chromatography (HPLC) using cross-linked acrylamide and styrene beads, respectively. Samples with higher BA content eluted earlier with normal phase HPLC, while opposite order with reversed phase HPLC, indicating that BA unit is less polar than EA unit. Observed composition distribution of copolymers was broader than the calculated one assuming copolymerization theory. The difference between them can mainly be explained by the peak broadening in the column and tailing.View full abstractDownload PDF (707K) -
Relation of Molecular Mobility to Higher Order Structures and Mechanical PropertiesToru NOGUCHI, Hitoshi IWABUKI, Kazuya NAGATA, Eisuke YAMADA2002 Volume 75 Issue 11 Pages 469-475
Published: 2002
Released on J-STAGE: May 28, 2007
JOURNAL FREE ACCESSPeroxide-crosslinked EPDMs filled with calcium-carbonate, silica, or carbon-black and unfilled EPDM were prepared at. varying cure time. Spin-spin relaxation time, T2, for these specimens were measured by a pulsed NMR spectroscopy with Hahn echo method. The decay curve was decomposed into two components, i.e. a short T2 and a long T2, which were respectively arising from network molecules and non-network molecules. For all these specimens, with the increase in the apparent crosslinking density, the network and the non-network T2 became shorter, resulting in the increase in tensile stress at 100% clongation and the decrease in the tensile strength. The higher order structures of calcium- carbonate-filled and silica-filled EPDMs were similar to that of unfilled EPDM. In the case of carbon-black-filled EPDM, however, the network T2 was found to be longer and the network fraction smaller than those of other specimens, while the apparent crosslinking density increased and the non-network T2 shorter. Carbon-black reinforcement seemingly did not relate to the higher order structures obtained by pulsed NMR.
The retention of stress under fatigue for all these specimens tended to decrease as the network T2 became longer. This result suggested the relationships between the fatigue behavior and the molecular mobility of network component.View full abstractDownload PDF (1169K) -
Toshiaki KASAZAKI, Hiroaki HANADA, Makoto SUZUKI, Mutsuhisa FURUKAWA2002 Volume 75 Issue 11 Pages 476-481
Published: 2002
Released on J-STAGE: May 28, 2007
JOURNAL FREE ACCESSThermal deterioration behaviors of the thick cylindrical polyurethanes were analyzed from the surface of samples to the inside. The polyurethanes were prepared from p-phenylene diisocyanate(PPDI), poly(hexamethylene carbonate) glycol(PHC), and chain-extenders which were 1, 4-butanediol (BD), 2, 2', 3, 3'-tetrachloro-4, 4'-diamino-diphenylmethane (TCDAM) and hydroquinone bis-2-hydroxyethyl ether(HQEE). Thermal deterioration behaviors of the polyurethanes aged at 150°C during 2 months were measured using Infra Red spectroscopy, dynamic viscoelastometer, DSC, and WAXS. While scission of allophanate crosslinkages and a little degree of micro-phase mixing occurred simultaneously in region of the surface of the samples, the micro-phase separation in the inside region was promoted by an annealing effect and reversible scission of allophanate crosslinkages. These behaviors depended on rigidity of hard segments.View full abstractDownload PDF (1007K) -
Keisuke CHINO, Makoto ASHIURA, Junichiro NATORI, Tetsuji KAWAZURA2002 Volume 75 Issue 11 Pages 482-487
Published: 2002
Released on J-STAGE: May 28, 2007
JOURNAL FREE ACCESSThermoreversible crosslinking rubber (TRC-IR) was easily synthesized by modification of isoprene rubber (IR) with maleic anhydride followed by the addition of 3-amino-1, 2, 4-triazole(ATA), in solid phase. The mechanical properties of the resulting rubber were more similar to the sulfur-vulcanized rubber than general thermoplastic elastomers (ex. SEBS). Although the tensile strength and elongation at break were lower than those of a corresponding sulfurcured rubber, the moduli were as high as those of sulfur-cured rubber. Re-forming of TRC-IR could be repeated more than 10 times without significantly changing its mechanical properties. Differential scanning calorimetry (DSC) and infrared analyses revealed that the superior mechanical properties and good recyclability are attributable to the strong hydrogen bonding. The TRC-IR showed an endothermic transition peak at around 185°C on the DSC chart, indicating cleavage of the hydrogen bonding. A hypothetical model which comprises strong crosslinking moiety formed by the seven-points hydrogen bonding was suggested. The thermoreversible crosslinking system was also applied to IIR and EPM. These rubbers also showed superior mechanical properties as well as excellent recyclability and fluidity.View full abstractDownload PDF (972K) -
Takeshi HOTAKA, Yasuhiro ISHIKAWA, Kunio MORI2002 Volume 75 Issue 11 Pages 488-493
Published: 2002
Released on J-STAGE: May 28, 2007
JOURNAL FREE ACCESSA resorcinol-formaldehyde (RF) resin is typically formulated in a compound for steel cord coating in order to improve the brass-rubber adhesion in the interface. A hexamethoxymethylmelamine (HMMM) is also formulated to accelerate the condensation reaction in the RF resin. Our study found that formulation of HMMM in the absence of RF resin has an ability to trap amines generated from N, N'-dicyclohexylbenzothiazole-sulphenamide(DCBS) accelerated vulcanization system, which prevents stress-induced corrosion crack in the brass layer at the brass plated steel cord. In this study, the nature of HMMM formulation was thoroughly investigated.
It was clarified that the physical properties of the vulcanized rubber such as crosslink density and strain modulus are effectively improved by trapping the residual amine component. When the RF resin was used in conjunction with the HMMM, the process of such amine-trap is tremendously interrupted due to the preferential consumption of the RF resin at condensation. However, the HMMM begins to trap the amine immediately after the complete of condensation reaction even during the formulation with the RF resin. It was revealed by ASTM pull-out test that the adhesion property is greatly improved by trapping the residual amine.View full abstractDownload PDF (1079K) -
Zihao Lu, Yoshitaka Uchiyama, Tomoaki Iwai2002 Volume 75 Issue 11 Pages 494-498
Published: 2002
Released on J-STAGE: May 28, 2007
JOURNAL FREE ACCESSA series of experiments was performed using a pin-on-disk type tribometer to investigate the μ-v characteristics of eight rubber specimens and their friction-induced vibrations. The experiments were made under various applied loads and sliding speeds. It was shown that the vibrations occurred in speed ranges in which the slopes of the μ-v curves were negative. The pin specimens of NR, SBR, and HNBR showed high negative slopes in the μ-v curves. At that time, marked friction-induced vibrations were observed. As the applied load is increasing, the amplitude of vibrations tended to decrease, while the speed ranges in which the vibrations occurred were also expanded to higher speeds. The vibration amplitude obtained by numerical analysis of the mechanical model coincided with the experimental results.View full abstractDownload PDF (859K)
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