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141.
The peel and tack properties of mixtures of polystyrene-block-polybutadiene-block-polystyrene (SBS) and a tackifier were investigated after these were crosslinked by ultraviolet (UV) irradiation at various amounts of benzophenone (BP) as a photoinitiator and trimethylolpropane mercaptopropionate (TRIS) as a crosslinking agent.The degree of crosslinking of polybutadiene (PB) block in the SBS mixture was qualitatively estimated from the amount of gel fraction as well as the change in the glass transition temperature of the PB block. The crosslinking of the PB block was done within 3 min after UV irradiation and the peel strength of crosslinked specimens was as low as 45[percnt] of specimens without crosslinking. Nano-tack and bulk tack properties as well as the surface tension of mixtures were measured depending upon amounts of BP and TRIS. 相似文献
142.
Yoshiyuki Sano Marcekazu Konda Chan Woo Lee Yoshiharu Kimura Takeo Saegusa 《大分子材料与工程》1997,251(1):181-191
A new technique for imparting antistatic properties to poly(ethylene terephthalate) (PET) fiber has been developed. In this technique, blend polyester fibers containing poly(ethylene terephthalate/5-sulfoisophthalate) (SIP-PET) were prepared by blend spinning and then treated with various cationic surfactants in the process of dyeing. The surfactants could effectively be immobilized on the fiber as the counter cations of the sulfonate groups of the 5-sulfoisophthalate (SIP) units and aid the release of static electrons formed in the fiber. Thus, the half-life time (t1/2) of leakage of static charge and the surface resistivity (Rs) of the blend PET fibers became much lower after treating. The best result was obtained with a methylated quaternary ammonium salt of a stearylamine-ethylene oxide (EO) adduct or hydrochloride of a laurylamine-EO adduct as the surfactant of which the number of EO units was around ten. Even after five washing cycles the t1/2 value of the fibers treated with these surfactants was kept lower than 30 s with the Rs value maintained in the order of 1013 Ω cm-2. Therefore, the present technique could be useful for practical production of polyester fibers with “semi-permanent” antistatic properties which can be recovered by re-treatment even if they were lost. 相似文献
143.
The infrared reflectance and transmission spectra of amorphous CdGe
x
As2 were investigated to study the amorphous structure with varying Ge content. The mid-infrared optical absorption edges of amorphous CdGe
x
As2 with 0<x<1.2, were observed in the range 1.6–1.7 m, indicating a structural similarity in short-range order throughout. Comparing the reflectance and transmission spectra of amorphous and devitrified crystalline phases established that the structures of amorphous CdGe
x
As2 transformed from the CdAs2 basic structure to the chalcopyrite (CdGeAs2) structure, as one progressed fromx=0 tox=1.2. The infrared spectra were interpreted interactively with radial distribution function, magnetic susceptibility, density measurements, and crystallization studies. The crystallization behaviour of amorphous CdGe
x
As2 that was heat treated at different temperatures was investigated using far-infrared transmission spectra. 相似文献
144.
Khaksar Pour Amin Chaw Seng Woo Palaiahnakote Shivakumara Tahaei Hamid Anuar Nor Badrul 《Multimedia Tools and Applications》2021,80(16):24121-24145
Multimedia Tools and Applications - Rating a video based on its content is one of the most important solutions to classify videos for audience age groups. In this regard, Film content rating and TV... 相似文献
145.
The effects of winglet offset distance, winglet coverage, and winglet cross section on the over-tip leakage loss for the plane tip have been investigated experimentally in a turbine blade cascade for a tip gap height-to-span ratio of h/s = 1.36 %. The results show that the over-tip leakage loss for the full coverage winglet increases steeply with increasing the winglet offset distance. This loss generation is attributed to flow disturbances over the forward-facing and backward-facing steps within the tip gap. The winglet flush mounted to the tip surface provides the best result. With the leading edge winglet portion or without it, the both-side winglet always provides better aerodynamic performance than the corresponding pressure-side winglet or suction-side winglet. Longer coverage of the both-side winglet leads to lower loss. Therefore, the full coverage winglet performs best in the loss reduction for the plane tip. In general, thinner winglet leads to better aerodynamic result, and the winglet cross section having a slant bottom surface with the smallest thickness at its outer end is recommended. 相似文献
146.
Chan-Geun Song Jonghan Won Inhoon Jang Hyeunseok Choi 《Journal of the American Ceramic Society》2021,104(9):4398-4407
In metal oxide nanofiber fabrication using the electrospinning method, heat treatment is performed at temperatures of 500°C or higher for crystallization and polymer desorption. Therefore, it is difficult to fabricate low-temperature phase metal oxides that crystallize at low temperatures. TiO2, a representative metal oxide often used as photocatalysts, is known to have higher photocatalytic activity in the low-temperature phase (anatase structure) than in the high-temperature phase (rutile structure). Studies on the fabrication of TiO2 anatase nanofibers using conventional electrospinning have reported disadvantages such as the partial expression of rutile structures and low crystallinity. This study developed an anatase TiO2 nanofiber as a high-efficiency catalyst based on the electrospinning method and a residual organic matter cleaning method that employs ultra-violet (UV) light. We fabricated nanofibers using the electrospinning method and implemented TiO2 nanofibers with the anatase structure through heat treatment at 260°C. Residual organics remaining after heat treatment of the fabricated crystalized TiO2 nanofibers were removed by exposing them to UV light, thereby improving photocatalytic efficiency. The photocatalytic efficiency of the fabricated TiO2 nanofibers was confirmed through a methylene blue (MB) decomposition experiment under visible light irradiation. The photocatalytic efficiency (time taken for the concentration of the MB solution to reach 50%) of the UV-treated TiO2 nanofibers was approximately six times higher than of P25 and the heat-treated nanofibers. 相似文献
147.
The superplastic deformation behavior of quasi-single phase Zn-0.3 wt. %Al was investigated. A series of load relaxation and
tensile tests was conducted at various temperatures ranging from RT (20 °C) to 200 °C. The recently proposed internal variable
theory of structural superplasticity was applied. The flow curves obtained from load relaxation tests were shown to consist
of contributions from interface sliding (IS) and accommodating plastic deformation. In the case of quasi-single phase Zn-0.3
wt.% Al alloy with an average agrain size of 1 μm, the IS behavior could be described as a viscous flow process characterized
by a power index of Mg=0.5. A large elongation of about 1400% was obtained at room temperature and the strain rate sensitivity parameter was about
0.4. Although relatively large-grained (10 μm) single phase alloy showed a high value of strain rate sensitivity comparable
to that of fine-grained alloy at very low strain rate range, IS was not expected from the analysis based on the internal variable
theory of structural superplasticity at room temperature. As the temperature increased above 100 °C, however, the contribution
from IS was observed at a very low strain rate range. A high elongation of ∼400% was obtained in a specimen of 10-μm-grain-size
at 200 °C under a strain rate of 2×10−4/sec.
Jointly appointed at Center for Advanced Aerospace Materials (CAAM) 相似文献
148.
A composite coating of aluminide-yttrium has shown excellent corrosion resistance in a cyclic high-temperature hot-corrosion environment. To understand the effect of yttrium on the stability of the composite coating, the specimens were prepared with various coating parameters of Y thickness, sequence of post heat treatment and surface condition before Y-ion plating. Performance of the composite coating was evaluated by isothermal oxidation and cyclic high-temperature hot corrosion. Isothermal-oxidation-test results show that the Y in the composite coating helps to form a thick and dense Al2O3 scale which is ductile and resistant to thermal stress. The Y in Al2O3 may act as a donor which leads to an increase in concentration of interstitial oxygen and, thus, increases in oxidation rate. The presence of Y2O3 and (Y, Al) O-type compounds in grain boundaries of Al2O3 and boundaries between the Al2O3 and NiAl effectively prohibits the fast diffusion of oxidants (such as O and S) and Al along grain boundaries. Consequently, it may induce slow diffusion through the matrix, and thus the corrosion resistance of the composite coating under cyclic hot corrosion increases substantially. 相似文献
149.
Hyoun Woo Kim Kwang-sik Kim Woon-suk Hwang Rafael Reif 《Metals and Materials International》2002,8(5):463-467
We investigated the effect of the rinsing and drying technique on the oxygen and carbon concentration on a silicon surface.
Rinsing in deionized water increased the interfacial oxygen concentration and helped generate defects. Blow-drying was more
efficient than spin-drying in reducing interfacial oxygen concentration. Exposure to the atmosphere was detrimental to obtaining
high crystallinity in the epitaxial layer. We evaluated the effectiveness of the cleaning process by observing the grown epilayer
and the epilayer/substrate interface. 相似文献
150.
Young-Wook Kim Yong-Seong Chun Ji Yeon Park Woo Seog Ryu Dong-Soo Park 《Metals and Materials International》2007,13(3):197-200
A new process using SiC fiber fabrics and SiC tapes to produce dense 2D SiC fiber-SiC (SiC/SiC) composites is demonstrated.
The strategy for fabricating the SiC/SiC composites involves: (i) alternately stacking the SiC fiber fabrics and SiC tapes
at room temperature, (ii) pyrolyzing of the stacked composites, and (iii) hot-pressing the pyrolyzed composites. By controlling
the hot-pressing temperature, it is possible to obtain dense 2D SiC/SiC composites with relative densities of >98%. The 2D
SiC/SiC composites show no degradation of the SiC fibers and a higher mechanical strength. 相似文献