ZrO2-Al2O3复相陶瓷的研究

以纳米ZrO 、微米Al O 为原料,采用无压烧结方式制备了ZTA 复相陶瓷。结果表明:nano-ZrO 的 2 2 3 2加入有利于制备细晶ZTA 复相陶瓷。此外,nano-ZrO 的加入对 Al O 陶瓷的显微结构也产生影响,ZrO 颗粒以 2 2 3 2“晶内型”和晶界型两种形式存在。合理的配方组成及制备工艺有利于 Z r O 以四方亚稳相存在。Z r O 含量为 2 23 0 w t % 时,其四方相含量可达 6 9 %,有利于应力诱导相变增韧,该 Z T A 复相陶瓷的抗弯强度、断裂韧性分别达到 604MPa、6.87MPa·m1/2。     

壳聚糖及其衍生物对重金属吸附性能的研究

壳聚糖分子中含有大量的氨基和羟基,可以进行多种化学改性,得到相应的衍生物。改性前后的壳聚糖对重金属都具有吸附作用,可以作为重金属离子的富集剂。文章综述了近年来壳聚糖及其衍生物在吸附重金属方面的研究进展,对比了不同产品对重金属的吸附容量和选择性,以及它们所适用的条件。文章指出,进一步开发水溶性和螯合能力优良的壳聚糖衍生物是今后研究的方向。     

Removal of Cu(II) from aqueous solutions by chelating starch derivatives

Two chemically modified starch derivatives, crosslinked amino starch (CAS) and dithiocarbamates modified starch (DTCS), were prepared and used for the removal of Cu(II) from aqueous solutions. CAS was found to be effective for the adsorption of Cu(II), which tended to form a stable amine complex. Adsorption of Cu(II) onto DTCS was higher than that onto CAS. Experiments showed that the adsorption processes of Cu(II) on both CAS and DTCS were endothermic, and followed Freundlich isothermal adsorption. For both adsorbents, dynamic modeling of their adsorption showed that the first‐order reversible kinetic model described the adsorption process. The adsorption rate constants of CAS and DTCS were 1.578 and 10.32 h^?1, respectively. From the results of the thermodynamic analysis, free energy ΔG, enthalpy ΔH, and entropy ΔS of the adsorption process were calculated. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3881–3885, 2004     

Autogenous and drying shrinkage of alkali-activated slag mortars

Shrinkage of alkali-activated slag (AAS) cement is a critical issue for its industrial application. This study investigated the mechanisms and effectiveness of shrinkage-reducing agent (SRA) and magnesia expansive agent on reducing autogenous and drying shrinkage of AAS mortars that were activated by liquid sodium silicate (LSS) solution with modulus (SiO₂/Na₂O molar ratio) of 0-1.5. The results showed that the autogenous shrinkage of AAS mortars increased with the increase of LSS modulus from 0 to 0.5, then decreased as modulus increased up to 1.5. The drying shrinkage consistently increased with the increase in the modulus of LSS. The oxyalkylene alcohol-based SRA could significantly reduce the autogenous and drying shrinkage of AAS mortars while the magnesia expensive agent was comparatively less effective. The autogenous shrinkage of AAS mortars was inversely proportional to the internal relative humidity, while the drying shrinkage was more related to the mass loss of samples. Mathematical models were established to describe the autogenous and drying shrinkage behavior of AAS mortars.     

3,4,5-三甲基叔丁基苯的合成与分析

介绍了以连三甲苯和氯代叔丁烷为起始原料 ,在自制的非均相催化剂W 1 0 0作用下一步合成3,4 ,5 -三甲基叔丁基苯的简便方法。经探索性试验、正交试验和单因素试验确定了最佳反应条件 :连三甲苯与氯代叔丁烷物质的量比为n连三甲苯∶n氯代叔丁烷 =1∶1 ,催化剂W 1 0 0的用量占连三甲苯的质量分数为 2 % ,反应温度 5℃ ,反应时间 7～ 8h ,在此条件下 ,3,4 ,5 -三甲基叔丁基苯的收率达到 79%以上     

Effect of nonsolvent additives on PES ultrafiltration membrane pore structure

Different nonsolvent additives, namely, diethylene glycol, n-butyl alcohol (NBA), and ethylene glycol monomethyl ether, were added into the casting solution (polyethersulfone/dimethylformamide/lithium chloride) to prepare ultrafiltration (UF) membrane via phase inversion. The effects of different additives and their concentration on the pore structure of the prepared UF membrane were studied. The cross-sectional morphology of the membrane was observed via scanning electron microscopy. The addition of nonsolvent additives improved the large-cavity structure of the membrane. When the additive was low-content NBA (1–3 wt %), the membrane pore structure transformed from large-cavity structure to fully sponge-like structure. When the content of additive NBA was 3 wt %, the flux of the prepared UF membrane was 130.45 L (m⁻² h⁻¹), the rejection of PEG20000 was 95.54% and the flux remained high at 4 bar in long-term stability test. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47525.     

Construction of efficient desalting layer on a cellulose acetate membrane by acetalized surface crosslinking treatment

For the purpose of enhancing the desalination performance, a desalting layer was successfully constructed on a cellulose acetate (CA) virgin membrane via acetalized surface crosslinking treatment. The acetalization crosslinking reaction consists of two hydroxyl groups reacting with one aldehyde group to remove one molecule of water. Results showed that the reaction occurred on the surface of the CA membrane, as measured by Fourier‐transform infrared (FTIR), differential scanning calorimeter (DSC), X‐ray photoelectron spectroscopy (XPS), and scanning electron microscope (SEM). The water flux and desalination performance were compared before and after crosslinking, and the formation of the desalting layer greatly improved the desalination performance of the membrane. In addition, the crosslinking temperature, crosslinking time, and formaldehyde solution mass fraction of the CA membrane structure and performance were explored. It was observed that the CA flat membrane showed better desalination performance, with a salt rejection rate of 98.55% and a water flux of 9.88 L/(m²·h), under a processing temperature of 100 °C 11% formaldehyde solution mass fraction and a crosslinking time of 60 min. POLYM. ENG. SCI., 59:913–918, 2019. © 2018 Society of Plastics Engineers     

Preparation of PET/LDH composite materials and their mechanical properties and permeability for O2

The terephthalate‐intercalated LDHs (TA‐LDHs) are used to improve the barrier properties of poly(ethylene terephthalate) (PET) for their application in liquid food packaging. First, TA‐LDHs were synthesized from freshly prepared metal hydroxides. PET/LDH nanocomposites were then prepared by a masterbatch process. The structures and morphologies of TA‐LDHs and PET/LDH nanocomposites were characterized using X‐ray diffractometer, transmission electronic microscopy, and scanning electron microscope. The mechanical performances and the oxygen permeability of the PET/LDH composites were measured using a precision universal tester and differential pressure gas permeameter, respectively. The influence of TA‐LDH content on their structures and properties was studied. PET/LDH nanocomposites with 1 and 2 wt% of TA‐LDHs are partially exfoliated nanocomposites, while PET/LDH with 5 wt% of TA‐LDHs is an intercalated nanocomposite. The PET/LDH nanocomposites prepared by a masterbatch process show better mechanical properties and gas barrier properties. PET/LDHs‐m2 with 2 wt% of TA‐LDHs could offer up to a 29.4% improvement in tensile strength over PET and the Young's modulus is increased by 38.9%. The O₂ permeation of PET/LDHs‐m2 with 2 wt% of TA‐LDHs is decreased by 46.2%. POLYM. ENG. SCI., 59:E366–E371, 2019. © 2019 Society of Plastics Engineers     

静电场中极板表面液膜蒸发特性研究

以静电场中水分子的极化和受力特性为基础,对热干烟气中极板表面液膜内水分子输运过程进行分析。考察了电场特征、液膜物性对静态高压电场中液膜蒸发特性的影响并提出了蒸发模型;同时研究了多场（温度、速度和静电）耦合作用下液膜蒸发过程中的主导作用机制。结果表明：离子风为静态高压电场中液膜蒸发的主要动力,蒸发速率是自然蒸发的6.7倍（25 kV）。液膜蒸发为等速过程,蒸发速率与电场强度呈正相关关系;液膜加入溶质,蒸发过程受抑制,蒸发模型变为等速和降速两个过程,最终液膜表面析出溶质;流场耦合静电场作用下,液膜蒸发速率随电压升高先缓慢上升（U＜20 kV）后快速上升（U＞20 kV）,流速和电压分别是这两阶段的主要影响因素;温度场耦合静电场作用下,蒸发速率大于单场叠加数值。研究结果为热干烟气中极板表面稳定成膜、系统水耗及空间电场中温湿度分布等问题的研究提供理论支撑。     

多组分氯盐体系镁锂分离规律初探

以Na₂CO₃为沉淀剂,初步研究了多组分氯盐混合体系（0.6 mol MgCl₂+1.1 mol LiCl+3.2 mol NaCl）中选择性沉镁的工艺规律。结果表明：在25~80 ℃,总C与总Mg物质的量比[n（C_T）/n（Mg_T）]为 0.8~1.1时,25 ℃形成针状MgCO₃·3H₂O,40 ℃以上形成Mg₅（CO₃）₄（OH）₂·4H₂O不规则片状团聚微球,其中40~50 ℃形成的片状物较为分散且粒径较小,导致固液分离困难。40 ℃时沉镁率最低。温度越高,Li₂CO₃越易形成,沉锂率越大。n（C_T）/n（Mg_T）越大沉镁率和沉锂率越高。室温（25 ℃）、n（C_T）/n（Mg_T）=1.0时,沉镁率达98%以上,且沉锂率<0.1%,镁锂分离效果最好。