聚对苯二甲酸丁二酯纤维在超临界二氧化碳介质中的染色研究

用超临界二氧化碳作介质，在40～120℃，10～30MPa条件下使用分散染料对聚对苯二甲酸丁二酯(PBT)纤维进行染色试验，并测定了3种分散染料在超临界二氧化碳介质中的溶解度。研究了染色温度、压力、时间及染料结构对染料上染量的影响，考察了染料溶解度与染料上染量的关系。试验表明，在80℃，20MPa下，染色30min，PBT纤维能得到良好的染色效果，上染量达4．01mg/g(分散红60)、2．43mg／g(分散黄23)、11．19mg/g(分散蓝79)。     

超临界CO2清洗技术

介绍了超临界CO2清洗的工艺及其应用,分析了超临界CO2清洗在技术、经济及环保方面的特点。     

Absorption of low molecular weight solutes into polyurethane in supercritical carbon dioxide

Absorption of a series of low molecular weight solutes into polyurethane was investigated in supercritical carbon dioxide with different conditions. The effect on the amount of solutes absorbed in polyurethane due to these factors such as pressure, temperature, absorption time, decompression time, the character of solutes, and the amount of cosolvent was examined by a gravimetric method. The absorption mechanism was discussed. The desorption of solutes in polyurethane showed a dependence on the logarithm of time. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 3162–3168, 2000     

Surface modification of polybutadiene facilitated by supercritical carbon dioxide

The hydrophilicity of polymers can be improved through surface modification, traditionally done with conventional organic solvents, but these may cause the deterioration of polymer bulk properties due to irreversible polymer swelling. However, supercritical carbon dioxide (scCO₂) not only swells the polymer reversibly, but also acts as a convenient transport medium for monomeric solutes, which may be subsequently polymerized. Thus we are able to modify the polymer surface without affecting its bulk strength and durability. Here we report scCO₂ surface modification of polybutadiene using ultraviolet‐visible (UV/Vis) and Fourier transform infrared (FTIR) spectroscopy. Monomers such as 3‐vinylbenzoic acid and crotonic acid are used to study the effects of pressure, solute structure, and reaction mechanism on the diffusion rates and partitioning of monomers between the fluid phase and the polymer. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 522–530, 2003     

超临界二氧化碳技术的应用进展

超临界流体(SCF)因其具有很多优异特性而广泛应用于各个领域。主要介绍了超临界二氧化碳流体技术在萃取、制备超细颗粒材料、化学反应、酶催化、高分子科学、化学分析以及精密仪器清洗几个领域中的应用进展。     

Hydrolysis of sugarcane bagasse using supercritical carbon dioxide to obtain fermentable sugars

This work evaluates the hydrolysis of sugarcane bagasse using supercritical carbon dioxide to obtain fermentable sugars in a single‐step process. The effects of temperature, pressure, despressurization rate, moisture content and reaction time on the amount of fermentable sugars released were assessed. Results obtained showed the feasibility of adopting the present procedure since it produced about 287 g of fermentable sugars per kg of dry bagasse, which corresponds to 60% yield on the basis of total cellulose. Such a result is very attractive from an industrial viewpoint because there is no use of toxic solvent, solvent removal is completed (no residues), and the method has very low water consumption since the process is a solid–gas reaction. © 2012 Society of Chemical Industry     

Preparation of molecularly imprinted polymers in supercritical carbon dioxide

Molecularly imprinted polymer nanoparticles were prepared in supercritical carbon dioxide using a noncovalent imprinting approach. In the present work, propranolol was used as a model template, methacrylic acid as a functional monomer, and divinylbenzene as a crosslinker. Under a high dilution condition, the heterogeneous polymerization resulted in discrete crosslinked polymer nanoparticles. Compared with the nonimprinted polymers, the imprinted nanoparticles displayed much higher propranolol uptake in a low polarity organic solvent. The use of a single enantiomer (S)‐propranolol as the template clearly demonstrated that the imprinted binding sites are chiral‐selective, with a cross‐reactivity towards (R)‐propranolol of less than 5%. The overall binding performance of the imprinted nanoparticles was comparable to imprinted polymers prepared in conventional organic solvents. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2863–2867, 2006     

利用超临界二氧化碳流体脱硫再生丁基橡胶

研究了硫黄硫化的丁基橡胶在超临界二氧化碳流体辅助下的脱硫降解行为,讨论了脱硫工艺的条件,并通过凝胶渗透色谱、核磁共振、差示扫描量热等对丁基再生胶的结构和性能进行了考察。结果表明,在二氧化碳的超临界状态下丁基橡胶的脱硫降解更加充分。脱硫的最佳工艺条件为: 反应温度180 ℃,反应压力14. 1 MPa,脱硫剂二苯基二硫的用量为橡胶质量的8%; 经过120 min 脱硫反应后丁基再生胶中溶胶的质量分数为98. 5%。在有热降解和脱硫剂参与的脱硫反应的共同影响下,丁基再生胶中溶胶的数均分子量降至原胶的40%左右; 再生胶主链上接枝了部分脱硫剂的苯环; 硫化和脱硫过程中在接枝于主链上的极性基团的影响下,再生胶中溶胶主链双键氢的振动峰几乎消失,但再生胶的玻璃化转变温度并没有明显变化。     

PP/超临界CO2连续挤出发泡成型

以超临界CO2为发泡剂,在连续挤出发泡过程中研究了超临界CO2用量对高熔体强度均聚聚丙烯(PP)发泡成型过程的影响.随着超临界CO2用量的增加,发泡挤出机口模压力降低,试样发泡倍率降低,泡孔尺寸变小,泡孔密度提高.在w(CO2)为3%,5%时,得到发泡倍率最高为13左右的PP发泡材料.w(CO2)为7%,发泡温度为12...     

Solubility of fatty acids in supercritical carbon dioxide

The solubilities of lauric, linoleic, myristic, oleic, palmitic and stearic acid in supercritical carbon dioxide (SC-CO₂) at different pressures and temperatures were measured. The solubility values obtained in this work were compared with previously published data, and possible causes for observed discrepancies were discussed. The solubilities of the six fatty acids were modeled by Chrastil’s equation, and estimated model parameters were used to plot the solubility isotherms of fatty acids at 313, 323 and 333°K (40, 50 and 60°C) as a function of SC-CO₂ density. The comparison of solubility isotherms of fatty acids and vegetable oil suggests that separation of fatty acids from triglycerides might be possible by using SC-CO₂ at densities less than 700 kg/m³. From the effect of temperature on fatty-acid and vegetable-oil solubility, it seems that the extraction yield could be increased without sacrificing the selectivity of SC-CO₂ for fatty acids by choosing a higher operating temperature. The data also suggest that fractionation of certain fatty acids might be possible by manipulating the processing conditions. Given the values of the constants, Chrastil’s equation could serve as a guideline for choosing appropriate processing conditions and predicting the effect of pressure and temperature of SC-CO₂ on solute solubility.     

Lipase-catalyzed glycerolysis of soybean oil in supercritical carbon dioxide

The transesterification of soybean oil with glycerol, 1,2-propanediol, and methanol by an immobilized lipase in flowing supercritical carbon dioxide for the synthesis of monoglycerides is described. A lipase from Candida antarctica was used to catalyze the reaction of soybean oil with glycerol, 1,2-propanediol, ethylene glycol, and methanol. Reactions were performed in supercritical carbon dioxide at a density of 0.72 g/L and at a flow rate of 6 μL/min (expanded gas). The substrates were added at flows ranging from 2.5 to 100 μL/min. Monoglycerides were obtained at up to 87 wt%, and fatty acid methyl esters at nearly 100 wt%. The reactivity of the alcohols paralleled the solubility of the substrate in liquid carbon dioxide. Glycerol has the slowest reaction rate, only 2% of that of methanol.     

Acylation of glucose catalysed by lipases in supercritical carbon dioxide

The acylation of glucose with lauric acid in a reaction catalysed by two Candida lipases and a Mucor miehei lipase in supercritical carbon dioxide (SCCO₂) was investigated. A linear dependence of the reaction rate on enzyme concentration was observed. Studies on the effect of temperature on enzyme activity showed that Candida antarctica lipase remains stable at temperatures as high as 70°C. Non-immobilised Candida rugosa lipase was found to have a temperature optimum at 60°C. The acylation reaction rate depended on the initial water activity of both substrates and enzyme; the optimum was 0·75 for Candida antarctica lipase, 0·53 for Candida rugosa lipase, and between 0·3 and 0·5 for Mucor miehei lipase. Candida rugosa lipase was most active at a molar ratio of sugar: acyl donor of 1: 3, while the optimum ratio was found to increase to 1: 6 when the reaction was catalysed by Candida antarctica and Mucor miehei lipases. © 1998 SCI     

Quality of wheat germ oil extracted by liquid and supercritical carbon dioxide

The extraction of wheat germ oil by liquid and supercritical CO₂ is described from the point of view of both operative method and pretreatment of raw material. The best conditions for wheat germ oil extraction are: pressure, 150 bar; temperature, 40°C; and solvent flow rate, 1.5 L/min at standard temperature and pressure. The yields and fatty acid compositions obtained are very similar to those resulting from the conventional extraction process using hexane as solvent (8.0 wt%), although a higher-quality oil is obtained by using CO₂ as solvent (free fatty acids, 12.4%; tocopherol content, 416.7 mg tocopherol/g wheat germ oil). These factors lead to the conclusion that the extraction process using CO₂ could be economically competitive with the conventional process, since it considerably simplifies the oil refinement stages and completely eliminates the solvent distillation stage, which are the most costly processing steps in terms of energy consumption.     

用超临界二氧化碳法制备超强吸水剂

以N，N’-亚甲基双丙烯酰胺(BIS)为交联剂，研究了疏水性单体丙烯酸十八酯(OA)与亲水性单体丙烯酸(AA)在超临界二氧化碳中的聚合反应，制备了超强吸水剂。结果表明，65℃、压力大于13MPa时，制备的产物都为白色固体粉末。用超临界二氧化碳萃取技术可以对产物进行纯化，50℃、20MPa下，产物经超临界二氧化碳萃取2次后纯度可大于95％，4次后单体残留率为0．28％。该超强吸水剂的吸水率有一定下降，然而保水率却得到提高。     

超临界二氧化碳染色技术研究进展

概述了超临界二氧化碳染色技术的染色机理,对不同染料的染色工艺条件的研究情况做了分析。阐述了染料研究和混合染料拼色研究的进展情况。对超临界二氧化碳的染色热力学和动力学性研究情况做了论述,对染料在超临界二氧化碳中的溶解度、染料在纤维与超临界CO2间的分配规律、染料在纤维中的扩散行为做了分析论述。对染色设备的国内外进展情况做了分析论述。指出了超临界二氧化碳染色技术产业化应用应解决的关键问题是增强染料的溶解和在纤维中的扩散,以及高压操作下大容积染色釜的研制。     

Cell removal with supercritical carbon dioxide for acellular artificial tissue

BACKGROUND: The objective of this work was to decellularize artificial tissue without using surfactant solutions. For this purpose, supercritical carbon dioxide was used as the extraction medium. RESULTS: Supercritical carbon dioxide containing a small amount of entrainer was a suitable medium to extract both cell nuclei and cell membranes from artificial tissue. Under gentle extraction conditions (15 MPa, 37 °C), cell nuclei were satisfactorily extracted from tissue within 1 h. In contrast, the efficiency of phospholipid removal depended strongly on the transfer rate of carbon dioxide in the interior of the tissue. Mechanical strength of tissue was not decreased even with prolonged treatment. CONCLUSION: Acellular artificial tissues could be prepared quickly by treatment with a carbon dioxide/entrainer system. The prepared acellular tissue could be obtained in absolutely dry condition. This is advantageous from the viewpoint of long‐term preservation without putrefaction and contamination. Copyright © 2008 Society of Chemical Industry     

Copolymerization of styrene and maleic anhydride in supercritical carbon dioxide

The copolymerization of styrene (St) and maleic anhydride (MA) was carried out in supercritical carbon dioxide (SC CO₂). It was found that St and MA are easy to copolymerize in SC CO₂ and the conversion can reach 97%, and that very fine and dry powders are obtained. The products were characterized using Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). GPC data showed that the molecular weight of the copolymer reach 3.62 × 10⁴ g mol^?1. Scanning electron microphotographs showed the minimum particle size of the product is about 200 nm. DSC measurements indicated that the glass transition temperature (T_g) of the copolymer increases with increasing the MA content in the copolymer. TGA curve showed that the copolymers were decomposed at about 350°C. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Lipase-catalyzed alcoholysis of cod liver oil in supercritical carbon dioxide

Enzymatic alcoholysis of cod liver oil, with an immobilized lipase, was carried out in supercritical carbon dioxide. The enzyme was catalytically active under the experimental conditions used. The reaction medium was investigated to preferentially extract ethyl esters, synthesized during the course of the experiment, from the unconverted cod liver oil substrate and side-products. The effect of pressure changes on the amount of tri-, di-, and monoglycerides and ethyl esters, present in both the extract and the remaining lipid residue, was determined. Furthermore, the fatty acid compositions of the lipid classes were analyzed, and the relative amounts of both eicosapentaenoic acid and docosahexaenoic acid to palmitic acid were determined. The results show that it is possible to preferentially extract the synthesized ethyl esters at low pressures. The extract collected at 9 MPa contained 64 g ethyl esters/100 g extract, while the total amount of all other lipid classes detected was 19 g/100 g extract. As the pressure was increased, the relative amount of the other lipid classes detected in the extract, especially triglycerides, was enhanced. The relative amounts of both eicosapentaenoic acid and docosahexaenoic acid to palmitic acid increased for some lipid classes in the extract. This increase was most pronounced for the monoglyceride lipid class. The integration of biocatalysis and product fractionation, applied in this study, suggests that the potential for biocatalysis in industrial processes is considerably wider than had been thought.     

超临界CO2二元系统相平衡的数值模拟

应用微扰理论,借助微扰状态方程,对超临界CO2 系统相平衡进行了模拟。编制了求解程序,介绍了状态方程中各参数的确定方法和程序模块的设计思想。针对超临界CO2 /非极性体系、超临界CO2 /极性体系,在不同温度、压力条件下的气液相平衡进行了计算,将计算结果与实验结果进行了比较,结果表明:微扰状态方程适合模拟超高压下的CO2 二元体系的相平衡。     

Surface modification of polymeric nanocomposite thin films using supercritical carbon dioxide

We report on an efficient and environmentally friendly means to modify surface properties of polymer films supported for nanoparticles. Ultrathin polystyrene (PS) films (<300 Å), in which inorganic nanoparticles were embedded, were exposed to supercritical carbon dioxide (scCO₂). The swollen structure was then preserved by quickly evaporating CO₂. X-ray reflectivity (XR) results showed that this procedure produced polymeric nanocomposite films with a low-density region of about 150Å at the polymer/air interface. The formation of the low-density layer was independent of the nature of the particles, indicating that the surface modification through exposure to scCO₂ may be a universal phenomenon regardless of a choice of nanoparticles.