丙三醇辅助水热法合成纳米棒状LiFePO4

在丙三醇存在下,以FeSO4·7H2O,LiOH·H2O和H3 PO4为原料,采用水热法合成了橄榄石结构的纳米棒状LiFePO4.产物结构与形貌用X射线衍射、红外、扫描电子显微镜、能谱分析测试技术进行了表征.讨论了反应时间、温度、混合溶剂比例对产品形貌的影响.结果表明,当V(水)/以丙三醇)=2:1时,在180℃反应2...     

不同添加物和制备方式对Al2O3热稳定性的影响

通过水溶液成胶和丙三醇络事助成胶制备了不同的结构的γ－Ａｌ２Ｏ３,研究了Ｌａ,Ｓｉ,Ｂａ以及Ｌａ,Ｓｉ和Ｌａ,Ｂａ双组分改性对它们结构热稳定的作用,讨论了改性元素的引入方式及硅铝比的影响。结果表明,丙三醇络合助成胶能明显提高Ａｌ２Ｏ３的比表面积和孔径,并能显著改善Ａｌ２Ｏ３的热稳定性。     

Preparation and characterization of rosin glycerin ester and its bromide

Rosin glycerin ester and its bromide were prepared from natural renewable rosin, glycerin and liquid bromine which were first subjected to an esterification reaction, followed by an addition reaction. Their structures were characterized by an infrared (IR) spectrum and their thermal resistance was conducted with thermal gravity (TG) and differential scanning calorimetry (DSC). It showed that the bromide in the rosin glycerin ester decomposed faster than the ester; hence it may be used as fire-resistant material.     

丝素-氧化石墨烯-甘油复合膜的制备及性能

采用浇铸法在丝素-甘油复合膜中添加氧化石墨烯,用以改善复合膜的综合性能,通过X射线衍射(XRD)、全反射傅里叶变换红外光谱(ATR-FTIR)、力学万能试验机、场发射扫描电镜(FESEM)和溶失率测试等方法研究了氧化石墨烯对复合薄膜结构与性能的影响。结果表明:加入氧化石墨烯后,丝素的晶型由Silk I向SilkⅡ转变,拉伸强度提高了32%。氧化石墨烯在丝素的结晶过程中起到成核剂的作用;氧化石墨烯可以增加复合膜在37℃水溶液中的稳定性。     

甘油单醚类化合物对纤维素膜的增塑作用

报道甘油单丁醚、单己醚、单庚醚和单辛醚４种化合物的合成，并用作再生纤维素膜的增塑剂．实验结果表明这４种甘油单醚类化合物对纤维素膜具有较好的增塑作用，随增塑剂单醚碳原子数的增加，增塑效果降低，但增塑剂与纤维素分子间相互作用增强．经甘油单己醚、单庚醚和单辛醚增塑的再生纤维素膜其耐水洗性明显高于甘油增塑的膜．     

磷脂核苷缀合物甘油结构修饰新方法及应用

通过环甘油磷脂核苷缀合物的亲核开环,为甘油结构修饰提供了一条简便有效的新路线.三乙胺对环甘油磷脂核苷缀合物的亲核开环,在室温下就能进行,合成了一类结构新型的以卵磷脂类似物作载体的核苷前药.     

Swelling of Lamellar Gel from Catanionic Hydro- and Perfluoro-Carbon Surfactant Mixtures by Refractive-Index Matching

Bilayer swelling behavior of cationic and anionic surfactant mixtures in solution induced by adding glycerin was investigated. The measurements were performed a system, cationic tetradecyltrimetylammonium bromide (TTABr), and anionic sodium perfluorodecanoate (C₉F₁₉CO₂Na) surfactant mixtures with their stoichiometric mole ratio being exactly 1 in aqueous solution. The non-precipitated phase of cationic and anionic hydro- and perfluoro-carbon surfactant mixtures being the mole ratio of 1:1 could be identified to be lamellar gel phase, which was characterized by freeze-fracture transmission electron microscopy (FF-TEM) and x-ray diffraction (XRD) measurements. Deuterium nuclear magnetic resonance (²H NMR) and rheology were used to characterize the phase transition from the lamellar gel to smaller vesicles. Phase transition from lamellar gel to smaller vesicles can be induced by adding glycerin to replace water. The addition of glycerin lowers the turbidity of the dispersion and swells the interlamellar distance between bilayers, which could be explained by matching of refractive index between solvent and bilayers.     

Development of UHPLC/Q-TOF Analysis Method to Screen Glycerin for Direct Detection of Process Contaminants 3-Monochloropropane-1,2-diol Esters (3-MCPDEs) and Glycidyl Esters (GEs)

The U.S. Food and Drug Administration’s (FDA′s) Center for Veterinary Medicine (CVM) has been investigating reports of pets becoming ill after consuming jerky pet treats since 2007. Renal failure accounted for 30% of reported cases. Jerky pet treats contain glycerin, which can be made from vegetable oil or as a byproduct of biodiesel production. Glycidyl esters (GEs) and 3-monochloropropanediol esters (3-MCPDEs) are food contaminants that can form in glycerin during the refining process. 3-MCPDEs and GEs pose food safety concerns, as they can release free 3-MCPD and glycidol in vivo. Evidence from studies in animals shows that 3-MCPDEs are potential toxins with kidneys as their main target. As renal failure accounted for 30% of reported pet illnesses after the consumption of jerky pet treats containing glycerin, there is a need to develop a screening method to detect 3-MCPDEs and GEs in glycerin. We describe the development of an ultra-high-pressure liquid chromatography/quadrupole time-of-flight (UHPLC/Q-TOF) method for screening glycerin for MCPDEs and GEs. Glycerin was extracted and directly analyzed without a solid-phase extraction procedure. An exact mass database, developed in-house, of MCPDEs and GEs formed with common fatty acids was used in the screening.     

The structures of low molecular weight glycerin propoxylates: An experimental,semi-empirical,and Monte Carlo study

A simple Monte Carlo model has been developed for calculating the structural features and properties of low molecular weight triols produced by the base-catalyzed propoxylation of glycerin. The model computes the probability of a reaction to a specific oligomer from the local site reactivities of model compounds with an adjustment for the molecular weight of the reacting oligomer. The resulting product array is then used to calculate typical polymer properties such as average molecular weight, polydispersity, and average chain length. Trial rate constants were estimated from the activation energies of MNDO-PM3 semi-empirical molecular orbital theory. For the compounds used to model the oligomer chain end groups, the activation enthalpies were found to be within the ranges reported for experimental values. Although the predicted enthalpies of activation were significantly higher for the alkoxylation directly at glycerin, this was found to be attributable to intramolecular hydrogen bonding in the reactants that was disrupted in the transition states. Although the hydrogen bonding energies were higher than what are normally considered typical, comparison tests showed that the calculated energies agreed well with experimental values of alkoxide anion–alcohol systems. The PM3 rate constants, when used to calculate Monte Carlo probabilities, predicted the isomer distribution of the four isomeric monopropoxylates with a error of 4%. Optimization of the model reduced this to 0.5%. However, to accurately predict the oligomer distribution of higher molecular weight adducts and other properties, the correction term (M₀/M_i)^b had to be included, where M₀/M_i is the ratio of the molecular weight of glycerin to the molecular weight of the oligomer undergoing alkoxylation, and b is assigned the value 0.7. Although b is empirical, it is consistent with a simple molecular mechanics (MM2) conformational study of the relative availability of the reactive end groups. When the final model was used to simulate the propoxylation of glycerin for a variety of PO/glycerin ratios, it was found to accurately reproduce properties such as primary hydroxyl content, polydispersity, oligomer distribution, and change in the monopropoxylate isomer ratio as a function of bulk PO/glycerin ratio. © 1995 John Wiley & Sons, Inc.     

Glass Transition Study of Nile Tilapia Myofibrillar Protein Films Plasticized by Glycerin and Water

Studies on glass transition of myofibrillar proteins based edible films are scarce. This work aimed to determine the T _g of edible films from Nile Tilapia myofibrillar proteins as a function of water content. Films with 30 or 70 g of glycerol/100 g of protein and several water content, were analyzed with a DSC TA 2010. Samples conditioned at water activity between 0.11 and 0.75, clearly showed one glass transition at low temperatures (<223 K), and another transition, less visible, above 273 K. DSC curves of samples conditioned ata _w=0.84, also showed an endothermic peak below 273 K. These results rendered evidence of phase separation within edible films. This revised version was published online in July 2006 with corrections to the Cover Date.