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Volume 48, Issue 9
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Kunio ESUMI, Kenjiro MEGURO1975 Volume 48 Issue 9 Pages 535-538
Published: September 20, 1975
Released on J-STAGE: November 20, 2012
JOURNAL FREE ACCESSThe electron donor properties of magnesia were investigated by means of 7, 7, 8, 8-tetracyanoquino-dimethane (TCNQ) adsorption. The radical-forming activity, i. e., the relative TCNQ anion radical concentration, was measured as a function of magnesia calcining temperature which was varied from 200 to 800°C. The result showed that the concentration of the electron donor sites on magnesia which can reduce TCNQ to the corresponding anion radical depends upon the calcining temperature and has the minimum value at 500°C. It was recognized from infra-red studies thatutw absorption bands are present at 3,720 and 3,640 cm-1 on the surface of magnesia and the intensities of the two bands changes against the calcining temperature. A correlation was found to exist between the concentration of electron donor sites, presumably, the concentration of surface hydroxyl ions, and the radical-forming activity.View full abstractDownload PDF (498K) -
Kunio ESUMI, Kenjiro MEGURO1975 Volume 48 Issue 9 Pages 539-543
Published: September 20, 1975
Released on J-STAGE: November 20, 2012
JOURNAL FREE ACCESSThe grinding effect on surface properties of magnesia and zinc oxide was investigated bymeans of chloranil adsorption. When chloranil was adsorbed on the surfaces of the ground oxides from its acetonitrile solution, the surfaces of the ground oxides acquired the characteristic color of each oxide. The presence of the chloranil anion radicals on the colored oxide surfaces was confirmed by the ESR absorption and electronic spectra. The radical-forming activity was determined by ESR. In the case of magnesia, the radical-forming activity decreased at the initial stage and then increased after 20 min. of the grinding time. On the other hand, the radical-forming activity of zinc oxide did not change against the time of grinding. The results suggest that the electron donor sites on the magnesia surface are affected with the grinding time and those of the zinc oxide are little affected.View full abstractDownload PDF (464K) -
Kunio ESUMI, Kenjiro MEGURO1975 Volume 48 Issue 9 Pages 544-546
Published: September 20, 1975
Released on J-STAGE: November 20, 2012
JOURNAL FREE ACCESSElectron spin resonance (ESR) and electronic spectra of 7, 7, 8, 8-tetracyanoquinodimethane (TCNQ) being adsorbed on TiO2 were used for the study of the surface properties of TiO2. It is recognized by these measurement that anatase titanium dioxide has the electron donor properties, but rutile has not.View full abstractDownload PDF (331K) -
Hideo MIMURO, Masana KOJIMA1975 Volume 48 Issue 9 Pages 547-554
Published: September 20, 1975
Released on J-STAGE: November 20, 2012
JOURNAL FREE ACCESSThe correlation between accelerated and natural weathering was examined by using white melamine alkyd paints pigmented various kinds of titanium dioxide at various pigment weight concentration (hereinafter called P. W. C.). Used were five kinds of titanium dioxide which differ in surface treatment, particle size, and particle size distribution, and are considered different in photochemical activities. The natural weathering was carried out at Florida, U. S. A. ; Yokkaichi, Kishu and Choshi Japan.' The accelerated weathering was made by using two kinds of testing machine at different cycles of operation, the details of which are shown below.
Dew Cycle Weather-O-Meter (hereinafter called Dew-WOM)
Light-on/Darkness =60 min/60 min
Sunshine Weather-O-Meter (hereinafter called Sun-WOM)
Spray cycle 1 : 18 min in 120 min
Spray cycle 2 : 12 min in 60 min
During the period of light-on without water-spray, black panel temperature was kept at 63±3°C.
Deterioration was periodically measured both by the degree of chalking and by the changes of 60°Cspecular gloss.
During the natural weathering at Florida and Yokkaichi, better durability was observed on the titanium dioxide having low photochemical activities and narrow particle size distribution, while at Choshi and Kishu, the better was the titanium dioxide of lower photochemical activities.
In the accelerated weathering by Dew-WOM or Sun-WOM at cycle 1, the titanium dioxide having smaller particle size with narrower distribution showed better results, irrespective of photochemical activities, while the weathering results by Sun-WOM at cycle 2 showed resemblances in gloss retention to those of the natural weathering at Florida and Yokkaichi, and in commencement of chalking to those at Kishu and Choshi.
In the natural weathering, the lower P. W. C. brought about the better gloss retention, and in the accelerated weathering by Dew-WOM or by Sun-WOM at cycle 1, the results were contrary. But, the weathering by Sun-WOM at cycle 2 gave similar results to those of the natural weathering.
It can be concluded that on melamine alkyd paint films pigmented with titanium dioxide, the results of natural weathering can be easily presumed by the results of Sun-WOM weathering at spray cycle of 12 min in 60 min because of the good correlation of results in the kinds of titanium dioxide and in P. W. C. between them.View full abstractDownload PDF (1077K) -
Hiroshi TAKAMI, Hiroshi MAKIUCHI1975 Volume 48 Issue 9 Pages 555-560
Published: September 20, 1975
Released on J-STAGE: November 20, 2012
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Taketo BABA1975 Volume 48 Issue 9 Pages 561-570
Published: September 20, 1975
Released on J-STAGE: November 20, 2012
JOURNAL FREE ACCESS -
Keisuke MORIYAMA1975 Volume 48 Issue 9 Pages 571-581
Published: September 20, 1975
Released on J-STAGE: November 20, 2012
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Shigeyoshi TANAKA, Eimitsu SUZUKI1975 Volume 48 Issue 9 Pages 582-586
Published: September 20, 1975
Released on J-STAGE: November 20, 2012
JOURNAL FREE ACCESSDownload PDF (626K)
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