PZT-polymer composites fabricated with YAG laser cutter

Piezoelectric composites have been constructed by YAG laser cutting of PZT ceramics and back-filling with silicone rubber. Composites containing 46–76 vol.% PZT have been prepared with several different rod sizes. The measured dielectric constant ranges from 310 to 598, d₃₃ from 297 to 305 pC/N, and g₃₃ from 87 × 10⁻³ to 62 × 10⁻³ V m/N. The influence of the new fabrication method on the piezoelectric properties of the composite is evaluated, and it is confirmed that an elastomer with low elastic modulus increases g₃₃ and suppresses the radial mode vibration in resonance. For the PZT-silicone rubber composites made by YAG laser cutting, g₃₃ can be enhanced in 1–3 composites to about three times the value for solid PZT. The piezoelectric properties are compared with those of 1–3 composites made by ultrasonic cutting. The g₃₃ values of composites fabricated by ultrasonic cutting are larger than those fabricated by laser cutting. These results indicate that to get higher values of g₃₃ it is necessary to perforate PZT with ditches of the same width.     

Illuminance dependency of L/Y (lightness/luminance-factor)-ratio effect

Using a modified model for predicting the perceived lightness of chromatic object colors for various adapting illuminances, the following two kinds of predictions were done for seven illuminance levels from 2 to 3000 lx on the basis of the Wysecki data. One concerned the contour lines of equal L/Y (lightness/luminance-factor) ratios in the whole chromaticity gamut, and the other the values of L/Y ratios for spectral colors. All the colors predicted have tristimulus value Y = 20. The computed results confirmed that the difference of L/Y-ratio effect found between the Wysecki and the Sanders-Wyszecki experiment was caused by the difference of the test adapting illuminance between them.     

Visual clarity and feeling of contrast

The visual clarity of a lighting environment is significantly affected by changing the general color rendering index (Ra) of its illumination. This effect has been studied by a number of researchers, but the cause of this effect has not been thoroughly studied. In order to clarify this, the mutual relations between visual clarity, lightness perception, and feeling of contrast are analyzed by using object colors under illuminations with various Ra values. the results obtained are as follows. (1) the visual clarity of a lighting environment is different from the lightness perception of the object colors in the environment. (2) the change in visual clarity of a lighting environment is highly correlated to a feeling of contrast between object colors under the illumination. (3) the effect of visual clarity is estimated effectively by assessing the feeling of contrast using a specially selected four-color combination. (4) the illuminance for equal visual clarity for any illumination is predicted by the equality of feeling of contrast under the same illumination specified by the gamut area made by the component colors of the four-color combination in a brightness and colorfulness space. (5) the effect of visual clarity under various illuminations cannot be predicted by using their Ra values.     

Relationship between brightness/luminance ratio and additivity‐law failure

The degree of additivity‐law failure of a mixture color consisting of two component chromatic colors has very complex characteristics depending on the used component colors and their mixing conditions. It is significantly affected by the mixture‐color chromaticity and by the brightness/luminance ratio at the chromaticity. A simple relationship was derived between the following quantities: degree of additivity‐law failure, additivity‐law luminance (luminance of the mixture color derived by postulating additivity law), and brightness/luminance ratio at the chromaticity of the mixture color. This relationship can be applied to any additivity‐law failure experiment and any formula on brightness/luminance ratio. © 2002 Wiley Periodicals, Inc. Col Res Appl, 27, 185–190, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/col.10045     

Chemical composition of silages treated with some volatile fatty acids,with special reference to the changes in sugars

In eight separate experiments with laboratory silos, silages were prepared with 50 mmol caproic (nC₆), isocaproic (iC₆), valeric (nC₅) and isovaleric (iC₅) acid additions per kg Italian ryegrass or cocksfoot, and stored at 25°C for 70 days. In the nC₆ and iC⁶ treatments, fermentation was consistently inhibited, and also the contents of water-soluble carbohydrates (WSC) were considerably higher in the silages than in the grasses. This increase in WSC was partly explained by the increase in glucose but the difference between WSC and “glucose + fructose” was clearly larger in the silages than in the grasses. In the nC₅ and iC⁵ treatments, various results were obtained; in some cases, presumably due to high dry matter content, fermentation was inhibited and WSC increased, while, in one case, fermentation was improved with higher lactic acid and lower butyric acid production than in the control silage. According to the results of five experiments with bag silos, although the inhibition of fermentation was observed by the treatment with nC₆, little or no increase in WSC during ensilage was found.     

Mechanical properties of silane‐treated,silica‐particle‐filled polyisoprene rubber composites: Effects of the loading amount and alkoxy group numbers of a silane coupling agent containing mercapto groups

The surface treatment of spherical silica particles with a silane coupling agent with mercapto groups was carried out. The treated silica particles were incorporated within polyisoprene and then vulcanized. The effects of the loading amount and alkoxy group number of silane on the stress–strain curve of the filled composite were investigated. For this purpose, silanes with dialkoxy and trialkoxy structures were used. The loading amount of silane on the silica surface was varied from 1 to 8 times the amount required for monolayer coverage. The stress at the same strain increased with the silane treatment, and it was higher in the dialkoxy structure than in the trialkoxy structure above 300% strain. There was no significant influence of the loading amount on the stress for the trialkoxy silane structure. However, the stress was influenced by the loading amount, and the maximum stress was observed at 4 times the silane amount required for monolayer coverage for the dialkoxy structure. The stress had a good relationship with the crosslinking density of silica‐filled polyisoprene rubber (measured with a swelling test). The reinforcement effect by the silane treatment of silica was found to be affected strongly both by the entanglement of the silane chain and polyisoprene rubber matrix and by the crosslinking reaction between the mercapto group of silane and polyisoprene rubber in the interfacial region. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009