Preparation and characterization of cyclo olefin copolymer (COC)/silica nanoparticle composites by solution blending

A series of organic cyclo olefin copolymer (COC)/SiO₂ nanocomposites, containing 1, 5, 10 and 15 wt% SiO₂ nanoparticles, were prepared by solution blending. The differential scanning calorimetric (DSC) analysis indicated that the glass transition temperature (T _g) of composites were higher than that of pure COC and raised significantly as the SiO₂ content increased from 1 to 15 wt%. The decomposition temperatures (Td) of composites were investigated by thermogravimetric analyzer (TGA) and showed 13 °C increase by the addition of 15 wt% SiO₂ when compared to pure COC. From the scanning electron microscopic (SEM) observation, finer size of silica was dispersed in the COC matrix without large agglomerates. The light transmittance of COC/SiO₂ composites was still higher than 85% as the SiO₂ content up to 10 wt%. The oxygen barrier property of the composite film show significant improvement when compared to pure COC.     

氧化锌铝(ZAO)陶瓷靶材制备及其薄膜性能

溶胶-凝胶方法制备的ZnO和Al2O3混合粉末经冷压预成型加真空低压烧结,制备了高致密度(相对密度99%)、低成本的ZAO陶瓷靶材.研究了ZAO靶材与无氧铜的粘接性能.用中频交流磁控溅射ZAO靶材的工艺制备了ZAO薄膜.利用SEM和XRD分析测试了陶瓷靶材断口形貌以及靶材和薄膜的结构.试验结果表明制得的ZAO靶材具有良好的粘接性和溅射性能,内部组织致密,靶材中有明显的ZnAl2O4相.在优化沉积工艺条件下,制备的ZAO薄膜方块电阻为35 Ω,电阻率可达3.84×10-4 Ω·cm,可见光透过率(λ=550 nm)可达91.1%.沉积态的ZAO薄膜具有很好的结晶性,并呈现(002)择优取向.ZAO薄膜有明显的紫外吸收限,带隙Eg约为3.76 eV.ZAO靶材的工业化磁控镀膜试验也取得了较好的结果.     

Solid-state reactive sintering of La2-xGdxZr2O7 transparent ceramics and their optical properties

Transparent polycrystalline La_2-xGd_xZr₂O₇ (x = 0.4–2.0) ceramics were fabricated by solid-state reactive sintering using commercially available La₂O₃, Gd₂O₃ and ZrO₂ nanopowders as the raw materials. The phase composition, microstructure evolution, densification and optical transmittance of the resulting ceramics were investigated. XRD and Raman results reveal that both the powders and ceramics are in single-phase pyrochlore structure. With the promotion of Gd content, the disorder degree of pyrochlore structure increases gradually while the cell parameters decrease. The x = 1.0, 1.2 and 1.6 samples exhibit high optical transmittance in the 450 nm-6.0 μm range, and the La_0.4Gd_1.6Zr₂O₇ sample shows the highest transmittance of 83.84%. The transparent La_2-xGd_xZr₂O₇ ceramics with high optical quality are available as scintillator matrice and high temperature window material.     

Influence of Lipids Isolated from Soybean Seed on Different Properties of Cassava Starch

The effect of lipids isolated from soybean seeds on the properties of cassava starch was investigated. Both polar and non‐polar lipid fractions were complexed with starch and the physicochemical and rheological properties were examined. The FTIR spectra of the complexed starches showed all the absorption bands characteristic of native starch with an extra minor peak at 2355 cm^‐1.The complexes prepared using the polar lipid fraction in diethyl ether as solvent exhibited a swelling volume of 32.5 mL/g compared to 36.9 mL/g for petroleum ether as solvent. A similar effect was observed with the non‐polar fraction. The apparent amylose content of the complexes was found to be lowered as a result of complexation. Total and soluble amylose contents and water‐binding capacity of the complexes were higher while their enzyme digestibility was noticeably lowered. The peak viscosity of the complexes was suppressed as a result of complexation. The polar layer exhibited a greater influence on the viscometric properties of the complexes with a higher breakdown ratio and hence higher stability. When compared to native starch, the percentage light transmittance of the complexes was noticeably reduced. The results indicate a considerable influence of the isolated lipid fractions on starch properties which can be useful in food and industrial applications.     

Nematic liquid crystal alignment on the ion beam-exposed ZnO film

This paper investigates the nematic liquid crystal (NLC) alignment on ion beam-exposed zinc oxide (ZnO) films. The ZnO films are deposited by a radio frequency magnetron sputtering. During the deposition of ZnO film, we supplied sufficient oxygen gas for high resistivity and transmittance. The deposited films show a high transmittance of over 90% and high resistivity of over 10¹⁰ Ω cm. The ZnO films show a high deposition rate of 26.7 Å/min. Images obtained via scanning electron microscopy of the ZnO film surfaces, before and after the ion beam exposure, show that groove patterns are formed being to be parallel to the ion beam exposure direction. LC cells are fabricated with the ion beam-exposed ZnO films. The NLC molecules align parallel to the ion beam exposure direction. The electro-optic and response characteristics of fabricated cells show the possibility of application to liquid crystal displays.     

Ag grid/ITO hybrid transparent electrodes prepared by inkjet printing

An Ag grid/indium tin oxide (ITO) hybrid transparent electrode was developed for printable optoelectronic devices using inkjet printing. By inserting an inkjet-printed Ag grid between inkjet-printed ITO electrodes, the sheet resistance of the inkjet-printed ITO electrode was significantly reduced from 6.5 to 0.54 Ω/square. However, the optical transmittance of the Ag grid/indium tin oxide (ITO) hybrid electrode gradually decreased with decreasing Ag grid separation distance due to the scattering of light on the Ag grid lines. From the figure of merit values of the Ag grid/ITO hybrid transparent electrodes, the optimized Ag grid width for the hybrid electrodes was determined to be 3 mm, which is consistent with the calculated results. The low sheet resistance and fairly high optical transmittance of the Ag grid/ITO hybrid transparent electrode suggests its use as a transparent electrode for inkjet printing-based printable optoelectronic devices.     

近红外偏振探测器校正方法

近红外偏振探测器是近年来一种新的探测器结构,它将光栅附在了焦平面探测器的表面.为了解决光栅透射率和角度不均匀对线偏振度测量的影响,采用了一种新的线偏振度求解方法.该方法对光栅透射率和光栅角度进行了校正,消除了光栅透射率和光栅角度不均匀性对线偏振度测量的影响,理论上表明了红外偏振成像质量与光栅透射率和光栅角度无关.实验结果显示,在使用黑体作为标定光源和不考虑偏振像元之间串扰的情况下,采用原有的计算方法得到的结果是真实值的14%~24%,透射率校正后的结果是真实值的80%~120%,透射率和角度校正后的结果是真实值的96%~104%.     

Transmittance predictions for transparent alumina ceramics based on the complete grain size distribution or a single mean grain size replacing the whole distribution

A simple method, based on the equivalent composite model or the dense polycrystalline model, is proposed for predicting the in-line transmittance in ceramics with a grain size distribution of birefringent crystallites. It is shown that the transmittance predictions based on the Rayleigh-Gans approximation are indistinguishable from those based on Mie theory, so that the latter can be replaced by the former. Based on normal distributions of different position and width it is shown that size distributions with smaller mean sizes lead to higher transmittance, whereas the effect of the distribution width on the transmittance is comparatively weak (with the narrowest distribution being the most favorable for high transmittance). The key result of this paper is the fact that for the distributions investigated (normal and log-normal) the transmittance prediction based the whole grain size distribution can be replaced by a transmittance prediction based on the geometric mean of the intensity-weighted distribution.     

Transmittance enhancement of spark plasma sintered CaF2 ceramics by preheating commercial powder

Spark plasma sintering (SPS) is a convenient approach for preparing transparent CaF₂ ceramics. However, carbon contamination is a key issue that should be addressed to achieve high transparency. In this study, a commercially available CaF₂ powder was preheated under vacuum before performing SPS to mitigate carbon contamination. During the preheating of the CaF₂ powder, impurities adsorbed on the particle surface, such as H₂O, CO₂, and O₂, are desorbed. Moreover, the interdiffusion of carbon contaminants is suppressed due to the pre-sintering of the raw powder. The in-line transmittance of the CaF₂ ceramic prepared from the preheated powder increased to 85 % at the wavelength of 1100 nm, which is 38 % higher than that of the ceramic prepared without preheating. In addition, the in-line transmittance increased with increasing grain size of the ceramic, possibly because of the decrease in the number of scattering sources with the reduction in the grain boundary fraction.     

PVA/Nano-SiO2薄膜的性能研究

通过熔融挤出法制备了聚乙烯醇(PVA)/nano-SiO2薄膜,并分别利用万能电子拉力机、透光仪以及差式扫描量热仪(DSC)和热萤分析仪(TG)对薄膜的透明性、力学性能和热性能进行了测试和研究.结果表明:随着纳米SiO2用量的增加,薄膜的拉伸强度、硬度、撕裂强度、透光率不断增加,热稳定性也得到提高,但是薄膜的断裂伸长率以及结晶度却呈下降趋势.