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Volume 83, Issue 10
Displaying 1-6 of 6 articles from this issue
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Regular Papers
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Ryuichi TAKAGI, Masayoshi ITO2010 Volume 83 Issue 10 Pages 311-317
Published: 2010
Released on J-STAGE: February 15, 2011
JOURNAL FREE ACCESSElectron spin resonance (ESR) and wide angle X-ray diffraction (WAXD) measurements under the tensile deformation were carried out for H-NBR, NBR and SBR vulcanizates with varying cross-link densities to discuss on the changes of network structure during tensile deformation. The H-NBR vulcanizates showed a strain-induced crystallization at room temperature, but the NBR and SBR vulcanizates did not. At a given stress, the radical concentration determined by ESR measurements was higher for H-NBR vulcanizates than for NBR and SBR vulcanizates. The degree of strain-induced crystallization at a given strain was likely to increase with the decrease of crosslink density. These results suggested that the strain-induced crystallization of H-NBR vulcanizates was accompanied by the partial breakdown of network structure in the vulcanizates.View full abstractDownload PDF (1159K) -
Asahiro AHAGON, Kazuo MIYASAKA2010 Volume 83 Issue 10 Pages 318-323
Published: 2010
Released on J-STAGE: February 15, 2011
JOURNAL FREE ACCESSDispersion of carbon black in compounds for practical use is examined from three aspects; effects of carbon black loading, deformation characteristics of raw polymer, and chain scission during mixing. A threshold carbon black loading, above which efficiency of dispersion is greatly improved, is found to exist. It coincides with the percolation threshold of the filler and also with the loading where appreciable Payne effect becomes detectable. The findings suggest that dispersion in practical compounds proceeds most efficiently via elongation of agglomerates. The relations of dispersion with deformation characteristics of raw polymer and with the extent of scission in agglomerates also support the elongation-driven mechanism in dispersion of the filler loaded above its percolation threshold.View full abstractDownload PDF (516K) -
Satoshi MIWA, Takako KIKUCHI, Yoshito OHTAKE, Keiji TANAKA2010 Volume 83 Issue 10 Pages 324-330
Published: 2010
Released on J-STAGE: February 15, 2011
JOURNAL FREE ACCESSThe degradation of ethylene-propylene-diene terpolymer (EPDM) in ozone water has been investigated. The surface of EPDM specimen degraded rapidly in ozone water. It showed adherence after ozone water treatment, since the polymer near the surface decomposed. From Fourier transform infrared (FT-IR) spectroscopy, the aggregation structure near the surface of EPDM treated with ozone in aqueous solution was different from that treated with ozone in gas phase. This may be due to that the degradation of EPDM by ozone in aqueous solution was initiated by hydroxyl radical, which was generated by self-decomposition of ozone. Through nuclear magnetic resonance (NMR) spectroscopy, the detected structures from degraded EPDM after ozone water treatment agreed with the most probable structures, which may be produced by ozone water treatment. It was concluded that the degradation of EPDM proceeded in ozone water, regardless of its good ozone resistance in air, because hydroxyl radical caused the decomposition of EPDM, which was initiated from proton abstraction from saturated hydrogen carbon linkage of EPDM main chain.View full abstractDownload PDF (1094K) -
Kazumi NAKAYAMA, Takayuki SAITO, Yoshito OHTAKE2010 Volume 83 Issue 10 Pages 331-336
Published: 2010
Released on J-STAGE: February 15, 2011
JOURNAL FREE ACCESSThe influences of moisture in un-crosslinked rubber on mechanical properties and crosslinking reaction were investigated in dicumyl peroxide (DCP)-crosslinked ethylene-propylene-diene terpolymer (EPDM), sulfur-crosslinked EPDM and sulfur-crosslinked natural rubber (NR).
The influences of water at the crosslinking reaction on mechanical and aging properties for DCP crosslinked EPDM and sulfur crosslinked EPDM were little. On the other hand, presence of water at the crosslinking reaction in the sulfur crosslinked NR made the crosslinking reaction progress excessively by shortening its scorch time, resulting in changing the properties such as mechanical strength and crosslink density, and deterioration of mechanical strength occured early. It was assumed that the water in un-crosslinked NR accelerated crosslinking reaction by promoting the formation of zinc stearate from stearic acid and zinc oxide, although the water in un-crosslinked NR at the crosslinking reaction did not directly react with NR molecule.View full abstractDownload PDF (378K)
General Reviews
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Shigeyuki TOKI2010 Volume 83 Issue 10 Pages 337-344
Published: 2010
Released on J-STAGE: February 15, 2011
JOURNAL FREE ACCESSNatural rubber is composed of rubber component (around 94 %) and non-rubber components (around 6 %) such as proteins, phospholipids, carbohydrates, metals and others. The functional groups of the ends of rubber chains react with non-rubber components and make naturally occurring networks. At the same time, non-rubber components make micelles, agglomerates and crystals. The superior mechanical properties in natural rubber to synthetic analogue are owed to hierarchical multi-scaled structures, that is, naturally occurring network and multi-scaled structures of non-rubber components. Synchrotron X-ray, atomic force microscopy, optical microscopy and simultaneous stress strain measurement revealed the role of hierarcic multi-scaled structures and naturally occurring network in natural rubber. Proteins in non-rubber components make multi-scaled (nano to micron) size of agglomerates and may not contribute to naturally occurring network since de-proteinized natural rubber show higher modulus and higher tensile strength and larger strain at break than original natural rubber in un-vulcanized state.View full abstractDownload PDF (1371K)
Technical Note
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2010 Volume 83 Issue 10 Pages Annc10_303
Published: 2010
Released on J-STAGE: February 15, 2011
JOURNAL RESTRICTED ACCESSDownload PDF (367K)
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