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Shigeyuki Toki Igors Sics Benjamin S. Hsiao Syozo Murakami Masatoshi Tosaka Sirilux Poompradub Shinzo Kohjiya Yuko Ikeda 《Journal of Polymer Science.Polymer Physics》2004,42(6):956-964
The molecular orientation and strain‐induced crystallization of synthetic rubbers—polyisoprene rubber, polybutadiene rubber, and butyl rubber [poly(isobutylene isoprene)]—during uniaxial deformation were studied with in situ synchrotron wide‐angle X‐ray diffraction. The high intensity of the synchrotron X‐rays and the new data analysis method made it possible to estimate the mass fractions of the strain‐induced crystals and amorphous chain segments in both the oriented and unoriented states. Contrary to the conventional concept, the majority of the molecules (50–75%) remained in an unoriented amorphous state at high strains. Each synthetic rubber showed a different behavior of strain‐induced crystallization and molecular orientation during extension and retraction. Our results confirmed the occurence of strain‐induced networks in the synthetic rubbers due to the inhomogeneity of the crosslink distribution. The strain‐induced networks containing microfibrillar crystals and oriented amorphous tie chains were responsible for the ultimate mechanical properties. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 956–964, 2004 相似文献
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Thawatchai Tuntulani Praput Thavornyutikarn Sirilux Poompradub Nongnuj Jaiboon Vithaya Ruangpornvisuti Narongsak Chaichit Zouhair Asfari Jacques Vicens 《Tetrahedron》2002,58(52):10277-10285
Tripodal aza crown ether calix[4]arenes, 5a, 5b, 6a and 6b, have been synthesized. The structure of protonated 5a was elucidated by X-ray crystallography to be a self-threaded rotaxane. Complexation studies of 5a and 5b towards anions using Na+ as countercation were carried out by 1H NMR titration in dimethylsulfoxide-d6 and the mixture of chloroform-d and methanol-d4, respectively. Ligands 5a and 5b were able to form 1:1 complexes with Br−, I− and NO3− and the complexation stability varied as follows: NO3−>I−>Br−. The effect of countercation on anion complexation was also investigated. The results showed that the association constants of 5a towards Br− in the presence of various cations varied as K+>Bu4N+>Na+. The enhancement in anion complexation ability of 5a may result from the rearrangement of the tripodal ammonium unit in the presence of K+. The neutral forms, 6a and 6b, were able to form complexes with transition metal ions such as Co2+, Ni2+, Cu2+ and Zn2+. The stability of the complexes followed the sequence: Ni2+2+Cu2+Zn2+. Compounds 6a and 6b may, therefore, potentially be used as either transition metal ion or anion receptors that can be controlled by pH of the solution. 相似文献
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Natchamon Watcharakul Sirilux Poompradub Pattarapan Prasassarakich 《Journal of Sol-Gel Science and Technology》2011,58(2):407-418
In situ silica reinforcement of natural rubber (NR) grafted with methyl methacrylate (MMA) (MMA-GNR) was achieved via the
sol–gel reaction of tetraethoxysilane (TEOS) by the use of solid rubber and latex solutions. Silica contents within the MMA-GNR
as high as 48 and 19 phr were obtained when using the solid rubber and latex solutions, respectively, under optimum conditions.
The conversion efficiency of TEOS to silica was close to 95%. The in situ formed silica MMA-GNR/NR composite vulcanizates
were prepared. MMA-GNR/NR composite vulcanizates reinforced with the in situ formed silica prepared by either method had similar
mechanical properties to each other, but a shorter cure time and higher mechanical properties than those reinforced with the
commercial silica at 9 phr. The TEM micrographs confirmed that the in situ formed silica particles were well dispersed within
the MMA-GNR/NR composite matrix, whilst the commercial silica particles showed a significant level of agglomeration and a
lower level of dispersion. 相似文献
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Yuko Ikeda Sirilux Poompradub Yuichi Morita Shinzo Kohjiya 《Journal of Sol-Gel Science and Technology》2008,45(3):299-306
Effect of amines on an in situ silica generation in natural rubber was investigated, and n-hexylamine, n-heptylamine and n-octylamine were found to increase the in situ silica content. The nanometer sized silica particles up to ca. 80 parts per
hundred rubber by weight were generated in situ in the rubber matrix via a sol–gel reaction of tetraethoxysilane. Additionally, dispersion of the silica in the rubbery matrix was more homogeneous
than that of commercial silica dispersed by a conventional mechanical mixing. In this in situ silica generation, the polarity
and solubility in water of amine were influential factors for controlling the in situ silica content in the rubbery matrix.
The obtained high in situ silica filled natural rubber was useful to prepare high performance nanocomposite elastomers. 相似文献
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Benjawan Chaichua Pattarapan Prasassarakich Sirilux Poompradub 《Journal of Sol-Gel Science and Technology》2009,52(2):219-227
The in situ silica filling of natural rubber (NR) was carried out via the sol–gel reaction using tetraethoxysilane. The effect
of the in situ silica content on the curing, mechanical, dynamic mechanical and thermal properties of the composite vulcanizate
materials was investigated in comparison to that with a commercial silica preparation. The Mooney viscosity of the in situ
silica filled NR vulcanizates showed a lower value compared with that of the commercial filled ones. The mechanical properties
of the in situ silica composite materials, i.e., the moduli and compression set, were improved compared with the commercial
silica filler NR vulcanizates. The reinforcement effect of in situ silica did not accord with the Smallwood equation but in
contrast was in good agreement with the Guth and Gold equation using a shape factor (f) which itself was in close agreement with estimates derived from independent TEM analysis. The pseudo-network structure of
the in situ silica was low, which resulted in a lower storage modulus at 25 °C. By filling NR with in situ silica, the thermal
properties of the composite vulcanized material were also improved, and well dispersed in situ silica particles within the
NR matrix were also observed. 相似文献
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Cuttlebone was proved to be a biomass for new reinforcing filler for natural rubber (NR). The cuttlebone particles were obtained by crushing cuttlebone and followed by sieving. Density and crystal structure of the cuttlebone were 2.70 g/cm3 and an aragonite form of CaCO3, respectively. The surface area and average diameter of the cuttlebone particles were measured and the reinforcement effect as filler for NR was investigated. The cuttlebone particles did not prevent a peroxide cross-linking reaction of NR, and mechanical properties of peroxide cross-linked NR filled with cuttlebone particles were found to be comparable with those of peroxide cross-linked NR filled with commercial CaCO3 filler. Presence of chitin on the surface of the cuttlebone particles was speculated to result in a good interaction between cuttlebone particles and NR, which may be ascribed to the mechanical properties of cuttlebone filled NR samples. 相似文献
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