Examination of the Dye‐Fixing Ability of Porous χ‐Alumina Flake Powders

Porous χ‐Al₂O₃ is a new material for fabricating coated inkjet printing paper. Paper coated with χ‐Al₂O₃ powders has excellent water fastness. This study investigated the dye‐fixing ability of χ‐Al₂O₃ powders through measurements of adsorption isotherms. The variations in zeta potential, pore volume, pore size distribution, and specific surface area of χ‐Al₂O₃ powders during the dye‐fixing process were also examined. The results show that χ‐Al₂O₃ powders have a strong affinity to dye colorants. The adsorption isotherm is classified as HA‐type and the adsorption data fit the Langmuir model. In addition to the positive‐charged surface of χ‐Al₂O₃ provides cationic sites for fixing dye colorants via electrostatic interaction, the porous structure on the surface of χ‐Al₂O₃ particles plays an indispensable role in trapping the colorant.     

Heavy water enrichment by thermal diffusion in the flat‐plate frazier scheme with column heights increased at a constant ratio for improved performance

This study investigates heavy water enrichment using the Frazier scheme of flat‐plate thermal diffusion columns with the column number adjusted and the column heights varied at a constant ratio with the total sum of column heights fixed. The equations for predicting the best number of columns and the best column‐height ratio for maximum separation are derived. Considerable improvement in performance is obtainable if the column‐height ratio and/or column number in a modified Frazier scheme are properly assigned, instead of using the conventional Frazier scheme of uniform column height with the same total sum of column heights. © 2013 Canadian Society for Chemical Engineering     

羟乙基纤维素和羧甲基纤维素溶液的稳定性

羟乙基纤维素(HEC)溶液的表面张力和视粘度很少受添加剂的影响,很稳定.羧甲基纤维素(CMC)溶液的稳定性则明显较差.但是,HEC:CMC=8:2(重量比)的溶液有与HEC溶液相近的稳定性.     

三元膨胀型混凝土防水剂的研究

按照砼防水剂国标规定的测试方法，对减水剂－胶态膨胀剂－晶态膨胀剂系统的三元复合膨胀型砼用防水剂进行了研究。研究表明：胶态膨胀剂的掺入能明显地　提高砼的抗渗性，降低砼的强度；共同掺入胶态与晶态膨胀剂，砼的抗渗性明显地提高，强度无明显的降低，而且具有补偿收缩的微膨胀性；掺三元膨胀型防水剂的砼，抗渗标号达到Ｓ３０；确定了三元复合膨胀型砼用防水剂的最佳配比。     

Smart Wearable Textiles with Breathable Properties and Repeatable Shaping in In Vitro Orthopedic Support from a Novel Biomass Thermoplastic Copolyester

In this study, materials with low melting temperatures and high toughness are developed for orthopedic applications. A series of an aliphatic copolyester based on sebacic acid (SeA), a green resource, is copolymerized with ethylene glycol, trimesic acid, aminocaproic acid, and adipic acid (AA) to produce poly(ethylene sebacate‐co‐ethylene adipate) (PESA) with various molar ratios through melt polymerization. Thermal characterizations of the PESA copolyesters are tuned with SeA and AA in varying molar ratios, exhibiting a crystalline phase with a lower degree of perfection. The melting point (T_m) and crystallization temperature (T_c) of the copolyesters are observed at 60–70 and 30–40 °C, respectively. Furthermore, a high Young's modulus ranging between 140 and 200 MPa is observed, which could be attributed to the 3D network structure formed by the trimesic acid unit used as a cross‐linking agent. Within the authors' research group, the PESA copolyesters are adopted to reinforce the mechanical properties of a 3D air mesh fabric as a composite application. Also, the highly breathable and low‐weight characteristics of 3D fabric with PESA copolyesters render them suitable for replacing traditional plaster in the future.     

Low‐Dielectric Constant and Low‐Temperature Curable Polyimide/POSS Nanocomposites

With the rapid development of ultra large scale integrated circuits, low stress, low thermal expansion, low dielectric constant, and low temperature curable (<250 °C) polyimides (PIs) with excellent mechanical, thermal properties are required. Unfortunately, high curing temperatures above 300 °C and limited dielectric property still remain to be solved. Herein, a new type of aminopropyl isobutyl polysilsesquioxane (POSS) with single vertex activity is introduced by in situ polymerization resulting in the PI‐POSS nanocomposites which exhibit a low dielectric constant (κ ≤ 2.6). Furthermore, low‐temperature curing at 200 °C (99.4% imidization) under the catalysis of quinoline is also achieved. The as‐prepared PI‐POSS nanocomposites also show excellent mechanical properties of which the tensile strength can reach up to 148 MPa and the elongation at break achieves 98%. Moreover, the temperature of weight loss 5% is as high as 550 °C and the glass transition temperature can also reach 349 °C. The as‐prepared PI‐POSS nanocomposites prove excellent electrical performance and mechanical properties, showing a huge market prospect of 5G chip packaging and millimeter wave antenna in the future.     

Raman spectra and extended X-ray absorption fine structure characterization of La(2−x)/3NaxTiO3 and Nd(2−x)/3LixTiO3 microwave ceramics

A-site deficient perovskite compounds, La_(2?x)/3Na_xTiO₃ (0.02 ≤ x ≤ 0.5) and Nd_(2?x)/3Li_xTiO₃ (0.1 ≤ x ≤ 0.5) microwave ceramics, were investigated by Raman scattering. Nd_(2?x)/3Li_xTiO₃ (0.1 ≤ x ≤ 0.5) was also investigated by extended X-ray absorption fine structure (EXAFS) measurement. The Raman shifts of the E (239 cm^?1) and A₁ (322 cm^?1) modes of La_(2?x)/3Na_xTiO₃ were found to decrease with x. However, the E (254 cm^?1) and A₁ (338 cm^?1) of Nd_(2?x)/3Li_xTiO₃ were found to blueshift with x, which was caused by Li substitution. The redshift of the A₁ (471 cm^?1) phonon of Nd_(2?x)/3Li_xTiO₃ (0.1 ≤ x ≤ 0.3) indicates that O–Ti–O bonding forces lessen with Li concentration, which is consistent with the EXAFS result that Ti–O bond lengths increase for 0.1 ≤ x ≤ 0.3. For x > 0.3, the EXAFS result shows that Ti–O bond lengths decrease. Moreover, Ti–O bond lengths show strong correlation with the microwave dielectric constants of Nd_(2?x)/3Li_xTiO₃.     

Design and fabrication of an affordable polymer micromixer for medical and biomedical applications

In this article, an affordable split‐and‐recombine polymer static micromixer and its fabrication process are described. The structure of the micromixer was designed to take advantage of the process capabilities of both ultraprecision micromachining and microinjection molding. This arrangement allows a considerably short machining time, high productivity, and flexibility as compared with many of the previous fabrication processes used in manufacturing of micromixers, for example, the cleanroom process. Moreover, in recent years, microinjection molding has become a cost effective mass production method for polymeric components with micro and nano scale features. Specifically, in this study four dominating processing parameters in microinjection molding, including melt temperature, injection velocity, packing pressure, and packing time were selected as variables to investigate their effects on replication quality. Both experimental and numerical results showed that the packing pressure and packing time played an important role on replication, followed by melt temperature while the injection velocity seemed to have no influence on replication. Finally, experiments using two colored water solutions were conducted to evaluate the device performance, and the mixing result demonstrated the successful fabrication and performance of the injection molded polymer micromixer. POLYM. ENG. SCI., 50:1594–1604, 2010. © 2010 Society of Plastics Engineers     

Operation analysis of a photovoltaic lighting system with battery and heater

An operation analysis is presented for a photovoltaic system consisting of the photovoltaic generator, the battery, the light, and the heater. An optimal resistive load for lighting is determined according to the characteristics of the battery. The working domain of the battery is marked out to display the range of the battery charge supplied by the photovoltaic generator. Before sunrise and after sunset, the battery supplies power to the light with an optimal resistive load. When the sun is above the horizon but sunset or not sunrise for the tilled photovoltaic module, the system is at rest. If the beam radiation is really incident on the surface of the module and induces a characteristic inside the working domain, all power will charge the battery. Once the characteristic is outside of the working domain, the resistive load is chosen to balance the currents of photovoltaic generator, battery charge, and heater. It is the only situation of concurrence. If the open-circuit voltage of the photovoltaic array under insolation is less than the zero-current voltage of the battery at the fractional state of charge, or if the battery is at full charge, the battery is disconnected from the photovoltaic system and the power output of the photovoltaic array to the heater is found by the method of maximum power point tracking.     

AN INVESTICATION OF A MARAGING STEEL WITH LOWER Ni AND Co CONTENTS

实验表明,降镍钴含锰铬12Ni马氏体时效钢有较高的强度和较好的韧性。观察了这类钢的时效沉淀相和位错组态;分析了位错的易交滑移特性;根据六角密排相沿位错线的层错区沉淀机制讨论了实验结果,还提出了用合金中原子的平均电子浓度作为预测马氏体时效钢高温奥氏体的稳定性和溶解度的判据。这些为马氏体时效钢降镍钴和合理的合金化提供有益的看法。