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Predecessor
Volume 76, Issue 6
Displaying 1-8 of 8 articles from this issue
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[in Japanese]2003 Volume 76 Issue 6 Pages 185
Published: 2003
Released on J-STAGE: May 28, 2007
JOURNAL FREE ACCESSDownload PDF (160K) -
Shinzo YAMASHITA2003 Volume 76 Issue 6 Pages 186-191
Published: 2003
Released on J-STAGE: May 28, 2007
JOURNAL FREE ACCESSRubber technology for operating milling and mixing with ease and a higher effeciency plays an important role in manufacturing rubber products. The milling patterns classified by Tokita and White are compared qualitatively with the time-temperature correspondence principle under a consideration of molecular structure of rubber.
Some chemical reactions of rubber attributed to mastication were outlined concerning “cold” and “hot” mastications. At the hot mastication SBR crosslinks predominantly to produce macrogels, contrary to degradation of NR. The macrogels induce poor processability and lowering of the mechanical properties. Some protection methods are cited.
Dispersive mixing of reinforcing filler is concerned with the size reduction of agglomerated particles produced by interparticle forces. Lowering the interparticle forces of ppt-silica and increasing its affinity toward rubber molecules are attainable by using bis(3-triethoxysilyl propyl)-tetrasulfane (TESPT).
The ease of the filler incorporation mainly depends on the milling patterns, whereas the filler dispersion proceeds by mechanical shear as shown in “Onion Model” proposed by Shiga and his coworkers. The stress for destroying the aggromerates are evaluated from the equation developed by Rumpf. The mechanisms of carbon gel formation and carbon scorch phenomenon caused by mixing are also discussed.View full abstractDownload PDF (1023K) -
Hiroshi TAKATSUGI2003 Volume 76 Issue 6 Pages 192-197
Published: 2003
Released on J-STAGE: May 28, 2007
JOURNAL FREE ACCESSThe mechanism of fillers incorporation and dispersion in rubber mixing were considered from an experimental point of view. The dispersion of fillers is stabilized by a bound rubber generated in the vicinity of the interface between rubber and fillers. Combination of shear with press-expansion in the mixing, contributes to dispersion of fillers into a rubber mixture.
From the practical viewpoint, the demerit of a tangential-type mixer generates a lot of micro void in the compound employing unsuitable rotation speed of the rotor. In other case, an intermeshing-type mixer brings causes unfavarable deviation of FIT (Filler Incorporation Time).View full abstractDownload PDF (1114K) -
Masayoshi ITO2003 Volume 76 Issue 6 Pages 198-203
Published: 2003
Released on J-STAGE: May 28, 2007
JOURNAL FREE ACCESSDevelopment of bound rubber phase in silica filled rubber compounds was discussed in connection with filler-polymer interactions. The amount of bound rubber increased with increasing the averaged size of agglomerate formed by silica particles, independent of chemical structure of rubber molecules. In addition, no trace of bound rubber was found in silica-filled rubber compounds in which no agglomerate existed. This suggests that the bound rubber phase corresponds to the entrapped rubber phase in the agglomerate. NMR results revealed that chemical interactions were negligible between silanol groups and non-polar rubber molecules such as IR and SBR. In that case, the averaged size of agglomerate was dependent on the silanol number per unit surface area of silica particles. For polar rubber molecules such as NBR, infra-red spectra suggested the existence of hydrogen bonding between silanol groups and nitrile groups of NBR. With increasing the nitrile group content of NBR, the averaged size of agglomerate as well as the amount of bound rubber decreased. The hydrogen bonding suppressed the development of agglomerate in the compound, leading to the decrease in the amount of bound rubber entrapped in the agglomerate. Further, the hydrogen bonding had no effect on the formation of bound rubber on the silica particles. Such formation mechanism of bound rubber in silica filled rubber compound is quite different from the case of carbon black filled rubber compounds.View full abstractDownload PDF (1454K) -
Asahiro ARAGON2003 Volume 76 Issue 6 Pages 204-209
Published: 2003
Released on J-STAGE: May 28, 2007
JOURNAL FREE ACCESSThe quality of the rubber with a formulation should be determined as a consequence of the combined effect of the unit processes of mixing. The unit processes playing major roles in mixing filled compounds would be dispersion of the filler, chain scission of the polymer, and bound rubber formation. In order to understand the relation between the mixing condition and the quality of the mixed material, the extents of these unit processes have to be measured, and the results have to be combined together to examine any relation with the quality of the material. Such an examination became possible with a recently developed method to determine directly the extent of chain scission. An example is introduced here, analyzing mixing of compounds with a highly loaded SBR formulation. It is shown that the three unit processes proceed cooperatively, and that the variations of the crosslink density and the tensile properties of the cured rubbers are the direct consequence of the variations of those unit processes.View full abstractDownload PDF (1059K) -
[in Japanese]2003 Volume 76 Issue 6 Pages 210-211
Published: 2003
Released on J-STAGE: May 28, 2007
JOURNAL FREE ACCESSDownload PDF (327K) -
Takashi HAKUTA2003 Volume 76 Issue 6 Pages 212-218
Published: 2003
Released on J-STAGE: May 28, 2007
JOURNAL FREE ACCESSFoamed rubber is now widely used in a variety of technological applications.
First, the text explains the general outline of technology for obtaining foamed rubber such as the choice of blowing agents, the balance a cure crosslinking reaction and a blowing agent decomposition reactions, and the mechanism of foamed rubber.
Second, the text explains manufacture technology of weather-strip sponge which is the typical sponge product of EPDM.
Finally, the text introduces the latest technology for contributing to the cost-reduction of foamed rubber, the safety sanitation and the performance improvement such as the high-cure crosslinking reaction-EPDM, the EPDM alloy and EPDM by hydrosilylation.View full abstractDownload PDF (1287K) -
Yoshitsugu Hirokawa2003 Volume 76 Issue 6 Pages 219-222
Published: 2003
Released on J-STAGE: May 28, 2007
JOURNAL FREE ACCESSPolymer gels consist of three-dimensional cross-linked polymer network and fluid. Internal structures relating to inhomogeneities of cross-linked polymer network are important factors characterizing the polymer gels. Internal structures of poly(N-isopropylacrylamide) gel obtained at various temperatures were observed by means of confocal laser scanning microscope and found to be bicontinuous structures consisting of dense and sparse cross-linked polymer networks. Generation process of the bicontinuous structures was also discussed on the basis of the results observed on temperature quenched gels.View full abstractDownload PDF (929K)
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