铝锆偶联剂的表征及应用

采用碱式氯化铝和氯氧化锆与有机物反应，合成了具有羟基稳定性和水解稳定性的铝锆偶联剂，并经红外光谱检测确证，用该偶联剂对纳米二氧化硅进行表面改性，发现可显著提高粉体的分散性。     

有机羧酸改性氮化铝粉体的抗水解性能

采用有机羧酸和PEG作为表面活性剂对工业AlN粉体进行表面改性处理,研究了改性前后AlN粉体的抗水解特性以及表面改性机制。研究结果表明,AlN表面与水分子发生化学反应,导致溶液的pH值迅速提高,表面包覆有机羧酸可有效地改善AlN粉体的抗水解性能;AlN粉体在水中浸泡48h后,氮含量基本保持不变,除了AlN晶相外,没有其他晶相出现,且改性粉体在高剪切应力的水基球磨介质中也保持较强的稳定性。     

端乙烯基聚醚改性三硅氧烷表面活性剂的合成及性能

以1,1,1,3,5,5,5-七甲基三硅氧烷(MDHM)和二乙烯基-1,4-丁二醇醚为原料,合成了聚醚改性的三硅氧烷表面活性剂。采用红外光谱(FT-IR)法和表面张力仪对其结构和性能进行了表征,并对其水解稳定性和乳化性能进行了测定。研究结果表明:产物的CMC(临界胶束浓度)为0.026 g/L、γCMC(最低表面张力)为18.3 m N/m和HLB(亲水亲油平衡)值为13.37,说明产物具有渗透、润湿之双重特性,并能显著降低水溶液的表面张力;当产物的p H为5~8时,其具有良好的水解稳定性;该产物具有优良的亲油性和亲水性,并且其乳化性能优异。     

由菜籽粕合成N—月桂酰基复合氨基酸表面活性剂

以菜籽粕为原料,用盐酸水解制得复合氨基酸液（ＡＡ）,再与月桂酰氯反应合成Ｎ－月桂酰基复合氨基酸表面活性剂。研究了水解条件对氨基酸得率的影响,探讨了物料配比、溶液的ｐＨ值、反应温度以及溶剂对合成反应的影响,实验结果表明,菜籽粕的最佳水解条件为：水解温度１０５￣１１０℃,盐酸的浓度６．０ｍｏｌ／Ｌ,水解时间１８ｈ,氨基酸的得率为８９．６％。合成Ｎ－月桂酰基复合氨基酸的最佳条件为月桂酰氯：复合氨基酸液：     

有机化钙硅胶的制备和性质

通过阴离子表面活性剂(SAS、SDS和SDBS)在钙硅胶上的吸附研究了有机化钙硅胶的制备。测定了此硅胶的Zeta电位、差热分析,红外光谱、物理结构、润湿热、接触角、热稳定性和水解稳定性、并对实验结果进行了讨论。     

表面活性剂对甘油三乙酯酸性水解的影响

采用酸碱滴定法测定了甘油三乙酯酸性水解的总速率常数k。试验发现，当加入各种类型常用的表面活性剂时，随着表面活性剂浓度变化，k值变化很小。这表明，甘油三酯的水解与单酯存在着较大的差别。一般表面活性剂对单酯水解有明显影响的静电作用与增溶效应这两大规律并不适于甘油三酯水解。这对于甘油三酯振荡反应的设计具有重要的指导意义。     

修饰SOD的稳定性研究

本文对采用低碳脂及酸修饰的ＳＯＤ在不同温度和ＰＨ值条件下的稳定性以及抗蛋白酶水解能力等进行了研究，结果表明：修饰ＳＯＤ具有半衰期长，对热和ＰＨ有较强的稳定性，对蛋白酶水解有较强的抵抗力。     

α-磺基脂肪酸甲酯钠盐的性能研究

考察了MES二钠盐质量分数随pH值和温度的变化,比较了MES与LAS、AOS、AES及Igepon-A等在洗衣粉、肥皂及香波中的应用性能,从而得出:pH值在3 5～9 0、温度80℃以下,MES具有良好的水解稳定性及优异的抗硬水能力,在高达1500×10-6mol·L-1硬度的硬水中,仍具有极强的去污力,在粉状、块状和液体洗涤剂中有良好的应用前景。     

新奥苷肽的水解和光解特性

[目的]明确新奥苷肽的环境化学规律,研究了其在水、土壤中的样品前处理方法,以及室内条件下新奥苷肽的水解和光解特性。[方法]室内条件下,进行了新奥苷肽在pH值4、7、9缓冲液中的水解试验,以及在水中、土壤表面的光解试验。[结果]新奥苷肽在pH值4、9的缓冲溶液中稳定性良好,在pH值7的缓冲溶液中稳定性差。(25±1)℃时新奥苷肽在p H值7条件下的水解半衰期为0.864 d;新奥苷肽在水中光解半衰期为35.5 h,在土壤表面光解半衰期为23.2 h。[结论]新奥苷肽的水解等级为易水解;在水中表现为难光解,在土壤表面表现为较难光解。     

枯草芽孢杆菌表面展示氨肽酶的构建及协同水解大豆蛋白

氨肽酶是蛋白质深度水解的重要协同酶,但游离酶使用成本高且稳定性差,限制了其工业化应用。本研究利用表面展示技术将来源于铜绿假单胞菌GF31的氨肽酶基因Aps展示到Bacillus subtilis WB800N芽孢的表面,构建了一种易分离且稳定性好的新型全细胞生物催化剂。通过免疫荧光分析,证明氨肽酶在芽孢表面正确表达。在最适反应温度60℃、pH=9.0的条件下,氨肽酶活力最高可达75.61U/g芽孢。将表面展示氨肽酶协同碱性蛋白酶水解大豆蛋白,在60℃、碱性蛋白酶与表面展示氨肽酶加入比例为2∶1、水解pH先为10.0后为9.0的条件下,水解5.0%的大豆蛋白8h,水解度最高可达55.50%,分别是表面展示氨肽酶与碱性蛋白酶单独水解时的3.3倍、1.5倍。同时16种游离氨基酸含量大幅度提升,其中疏水性氨基酸亮氨酸、酪氨酸和苯丙氨酸含量分别增加19.21mg/L、8.59mg/L和16.77mg/L,鲜味氨基酸谷氨酸、天冬氨酸含量增加13.98mg/L和4.11mg/L,说明表面展示氨肽酶在蛋白质的深度水解及对蛋白水解液脱苦、增鲜方面具有显著的作用,具有良好的工业应用前景。     

Hydrolytic stability of cured urea‐formaldehyde resins modified by additives

Urea‐formaldehyde (UF) resins are prone to hydrolysis that results in low‐moisture resistance and subsequent formaldehyde emission from UF resin‐bonded wood panels. This study was conducted to investigate hydrolytic stability of modified UF resins as a way of lowering the formaldehyde emission of cured UF resin. Neat UF resins with three different formaldehyde/urea (F/U) mole ratios (1.4, 1.2, and 1.0) were modified, after resin synthesis, by adding four additives such as sodium hydrosulfite, sodium bisulfite, acrylamide, and polymeric 4,4′‐diphenylmethane diisocyanate (pMDI). All additives were added to UF resins with three different F/U mole ratios before curing the resin. The hydrolytic stability of UF resins was determined by measuring the mass loss and liberated formaldehyde concentration of cured and modified UF resins after acid hydrolysis. Modified UF resins of lower F/U mole ratios of 1.0 and 1.2 showed better hydrolytic stability than the one of higher F/U mole ratio of 1.4, except the modified UF resins with pMDI. The hydrolytic stability of modified UF resins by sulfur compounds (sodium bisulfate and sodium hydrosulfite) decreased with an increase in their level. However, both acrylamide and pMDI were much more effective than two sulfur compounds in terms of hydrolytic stability of modified UF resins. These results indicated that modified UF resin of the F/U mole ratio of 1.2 by adding acrylamide was the most effective in improving the hydrolytic stability of UF resin. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Aminopropylsilane treatment for the surface of porous glasses suitable for enzyme immobilisation

During silylation of porous glass with 3-aminopropyltriethoxysilane, the properties of the carrier affected the concentration of bound amino groups, the formation of aminopolysiloxane mono- or multilayer on the surface, and the hydrolytic stability of the layer formed. The influence of the carrier depended on the specific surface area and the size of pores. In contrast to silylation performed in organic solvents, in aqueous solutions a monolayer of aminopolysiloxane of high hydrolytic stability was formed on the surface of porous glass. Tetraethoxysilane modification of porous glass prior to silylation with aminosilane yields carriers of increased hydrolytic stability. Glucoamylase immobilised on carriers, that were modified in aqueous solutions, exhibit higher enzymatic activity.     

Synthesis and evaluation of water-reducible acrylic–alkyd resins with high hydrolytic stability

Relatively poor hydrolytic stability is one of the major drawbacks of waterborne alkyd resins. Therefore, the shelf life of the paints containing these kinds of resins is usually short. In this research, the hydrolytic stability of water-reducible alkyd resins has been improved by employing polyacid acrylic copolymers in alkyd resins structure. In addition, the effect of other raw materials (such as neutralizing agent) and synthesis conditions on the resins properties was investigated. The results showed that the optimum synthesized water-reducible acrylic–alkyd resins had a high hydrolytic stability and their acid values increased only 23.5% after 4 months storage at ambient temperature. The synthesized resin was also used in an air-drying water-reducible lacquer formulation and its physical and mechanical properties were evaluated.     

Lysosomes and essential fatty acid deficiency

The hydrolytic activity usually associated with lysosomes increased in the homogenates and subcellular fractions of rat liver as a result of essential fatty acid (EFA) deficiency. The proportion of the total (tissue homogenate) activity found in each subcellular fraction, however, was unchanged by EFA deficiency. Lysosomes isolated from normal and EFA-deficient rat livers differed significantly in their stability to thermal and osmotic variations. This suggested that lysosomal membranes, like other membranes, were altered by EFA deficiency. In spite of increased tissue-bound hydrolytic activity and altered lysosomal membranes, hydrolytic activity of the serum was not markedly changed in EFA deficiency. These minor changes in hydrolytic activity and in lysosomal membrane stability seemed insufficient to explain the general lesions of EFA deficiency. Published with the approval of the Director of The Wisconsin Agricultural Experiment Station.     

Extremely enhanced hydrolytic stability of poly(ethylene terephthalate) films

Poly(ethylene terephthalate) (PET) films possessing extremely enhanced hydrolytic stability were developed by combining the improved processes of polymerization, melt extrusion, and biaxial stretching. The PET films obtained from the combined process were better than commercially available PET films with highest hydrolytic stability at present. An accelerated test (at 120°C and 100% relative humidity) was performed to learn the key parameters governing elongation‐based hydrolytic durability of PET films. The results suggested that ultimate hydrolytic stability was because of the combined effects of significant decrease in the content of carboxylic acid terminal groups and enhanced crystallinity. Another reason for this was an increase in ground‐state dimer sites due to intermolecular stacking between terephthalate units. These dimer sites were probably located in the densely packed amorphous regions, as suggested from the intrinsic fluorescence spectrum of PET films. The PET films developed in this study are very useful in outdoor applications such as backsheet materials in solar cell modules. POLYM. ENG. SCI., 58:261–271, 2018. © 2017 Society of Plastics Engineers     

改善液压油水解安定性、放气性及破乳化性的研究

就改善液压油的水解安定性、放气性及破乳化性进行了研究,试验表明金属减活剂和高碱度清净剂能改善液压油的水解安定性,清净剂还可改善液压油的破乳化性,硅型和非硅型抗泡剂对放气性和抗泡性的影响不同,需从配方技术上进行平衡,才能达到效果.     

Synthesis and characterization of sulfonated block copolyimides derived from 4,4'‐sulfide‐bis(naphthalic anhydride) for proton exchange membranes

A series of sulfonated copolyimides (SPIs) with hydrophilic segment length of 20–60 based on 4,4′‐sulfide‐bis(naphthalic anhydride) (SBNA) have been successfully synthesized to improve hydrolytic stability and proton conductivity. The SPI membranes were cast from their m‐cresol solutions, and they were characterized by determining the water uptake, water swelling ratio, mechanical properties, hydrolytic stability, oxidative stability, and proton conductivity. It was found that the water uptake of SPI membranes was low and decreased as the hydrophilic segment length increased, which led to good dimensional stability. In addition, the SPI membranes with low ion‐exchange capacity (IEC) value displayed excellent hydrolytic stability and retained good mechanical properties even after harsh hydrolysis testing, in which the block SPI with hydrophilic segment length of 40 had the best hydrolytic stability, while those with high IEC value showed an apparent decrease. All of the block SPI membranes show better conductivity than the random ones at the temperature range from 30 to 70°C. Interestingly, the proton conductivities of random SPI membranes were higher than that of corresponding block ones at 90°C. The block SPI with hydrophilic segment length of 40 gave the highest proton conductivity as the temperature increased among the block SPIs. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41501.     

PBO纤维稳定性的研究进展

介绍了聚对苯撑苯并双噁唑(PBO)纤维的热分解行为、热分解机理、水解稳定性、光稳定性及化学稳定性等方面的研究进展。PBO纤维的热稳定性和化学稳定性优良,其水解稳定性和光稳定性较差。通过热处理可提高PBO纤维的强度和模量。指出应进一步研究PBO纤维的稳定性,提高其性能,扩大应用领域。     

Announcements

Hydrolysis of poly(ester urethane ureas) (PURUs) is a complex phenomenon which impedes the analysis of the relationships between their composition and hydrolytic stability. Hydrolytic stability of PURUs decreases due to rising (i) polyol acidity, (ii) content of ester groups, (iii) flexibility and (iv) hydrophilicity of the backbones; molar mass of polyols does not seem to have any appreciable effect on it. Negative influence of ether groups (which have better hydrolytic stability than ester groups) is probably linked to the increase in the backbone flexibility and, consequently, to easier access of water molecules to ester groups. Positive effect of aromatic rings in polyols can be ascribed to enhanced rigidity of the backbones as well as to increased hydrolytic stability of adjacent ester groups due to the resonance effect. It can be presumed that the mentioned effects will superpose and simultaneously predestine the resulting hydrolytic resistance. Considering the observed tendencies, it is possible to qualitatively predict the trends how the hydrolytic stability will respond to changes in PURUs composition.     

Multiblock sulfonated poly(arylene ether sulfone)s with fluorenyl hydrophilic moieties for PEMFC applications

Multiblock sulfonated poly(arylene ether sulfone) (MB-SPAES) ionomers containing fluorenyl hydrophilic moieties were synthesized and converted into proton exchange membranes (PEMs) through solution casting, as well as other two types of MB-SPAES membranes containing hydrophilic biphenyl and hexafluoroisopropyl diphenyl moieties for the comparison. Chemical structures of the MB-SPAES ionomers were confirmed by ¹H NMR spectrometer. Fundamental physical properties were characterized based on the ionic group content, the hydrophilic/hydrophobic block structure and length, including ion exchange capacity (IEC), water uptake, size change, mechanical property, proton conductivity, hydrolytic stability and fuel cell performance. All the obtained MB-SPAES membranes were transparent and mechanical ductile, suitable for PEM applications. Water uptake and size change results showed that the MB-SPAES membranes containing fluorenyl hydrophilic moieties absorbed less water and swelled smaller in water than the other two types at similar IECs, indicating their better dimensional stability. Proton conductivity and hydrolytic stability results indicated that the fluorenyl hydrophilic moieties were also favorable to gain better proton conductivity and hydrolytic stability.