Non-isothermal decomposition kinetics of hydrogarnet in sodium carbonate solution

Carbonation decomposition of hydrogarnet is a significant reaction of the calcification-carbonation new method for alumina production by using low-grade bauxite. In this work, non-isothermal decomposition kinetics of hydrogarnet in sodium carbonate solution was studied by high-pressure differential scanning calorimetry (HPDSC) at different heating rates of 2, 5, 8, 10, 15 and 20 K·min^-1, respectively. The activation energy (E_a) was calculated with the help of isoconversional method (model-free), and the reaction mechanism was determined by the differential equation method. The calculated activation energy of this reaction was 115.66 kJ·mol^-1. Furthermore, the mechanism for decomposition reaction is Avrami-Erofeev (n = 1.5), and the decomposition process is diffusion-controlled.     

Alkaline dyeing of polyester and polyester/cotton blend fabrics using sodium edetate

An alkaline dyeing of polyester with an alkali‐stable disperse dye, Dianix® Scarlet AD‐RG, was developed using sodium edetate as an alkaline buffering agent. The results obtained indicate the suitability of using sodium edetate for alkaline dyeing of polyester when compared with the control alkaline dyeing using Dianix AD system. Selected mono and bifunctional reactive dyes were used in combination with the alkali‐stable disperse dye for dyeing of polyester/cotton blend. Different dyeing methods for cotton and polyester/cotton blend fabrics using sodium edetate were evaluated in comparison with their respective control alkaline dyeing methods. The results of using sodium edetate in one‐bath two‐stage and two‐bath dyeing of polyester/cotton blend were comparable with that of the control dyeing method. Particularly, no change in the leveling and fastness properties was evaluated for all samples irrespective of the dyeing method. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Flame-resistant polyester/cotton fabrics

New experimental results are reported for the modification of 50/50 polyester/cotton blend fabrics made from bromine-free and bromine-containing polyester with a reactive flame retardant compound of high phosphorus content. Reaction of the cotton in the blend with methyl-phosphonic diamide yields modified fabrics in which flame resistance is attained without impairment of fabric hand. The level of flame resistance depends on the amount of insolubilized phosphorus in the treated fabric, but the hand is essentially unchanged even for fabrics of high phosphorus content which pass the vertical test of DOC-FF-3-71. The results of this work provide a basis for improved definitions of future approaches to the development of flame resistant polyester/cotton blend fabrics.     

Alkaline dissolution monitoring of radial‐type polyester microfiber fabrics by a cationic dye‐staining method

The alkaline dissolution behavior of radial‐type polyester microfibers during high‐temperature alkali treatment and cold‐pad batch alkali treatment was successfully monitored using a cationic dye‐staining method. The weight reduction behavior of the alkali‐treated microfiber fabrics and their staining behavior with a cationic dye were compared. In addition, the termination of dissolution monitored by both methods was confirmed by scanning electron microscopy. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 279–285, 2006     

Effects of sodium hydroxide and calcium hydroxide on polyester fabrics

The results of a comparison between the effects of sodium hydroxide and calcium hydroxide on poly(ethylene terephthalate) fabrics are presented. Calcium hydroxide can produce weight‐loss effects similar to an aqueous solution of sodium hydroxide. The effects of some treatment variables on weight loss, fiber diameter, bending rigidity, and strength of yarns taken from fabrics are examined. The results are explained in terms of current views of polyester alkaline hydrolysis. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 631–637, 1999     

涤棉织物化学回收工艺研究

以废旧涤棉织物为原料,乙二醇(EG)为醇解剂,通过改变醇解时间、醇解温度、EG/废旧涤棉织物中聚对苯二甲酸乙二醇酯(PET)质量比(mEG/mPET)、催化剂种类及用量等研究了蓬松态下废旧涤棉织物的醇解工艺,以及醇解过程对涤棉织物中棉纤维性能的影响。结果表明:随着醇解时间、醇解温度的提高,mEG/mPET的增大,涤棉织物的醇解程度增大,各参数达到一定程度后醇解程度基本不变;最佳醇解工艺为涤棉织物中mEG/mPET为2/1,催化剂用量为涤棉织物中PET质量的0.30%,醇解温度196℃,醇解时间1 h;在乙酸锌、碳酸钠、乙酸钾、氯化镁4种催化剂中,碳酸钠综合催化效果最佳;经醇解过程后涤棉织物中棉纤维表面变得粗糙,力学性能有较大下降。     

Thermal decomposition kinetics of sodium perborate tetrahydrate to sodium metaborate by using model-fitting and model-free methods

Model-free and model-fitting methods have been applied to data for nonisothermal and isothermal decomposition of sodium perborate tetrahydrate to sodium metaborate. The kinetic triplet (f(a), A and E) of sodium perborate tetrahydrate was found by model fitting method defined with a single step reaction, which has an excellent fit for nonisothermal data and obeys different kinetic models and yields highly uncertain values of Arrhenius parameters. The isothermal and nonisothermal data for thermal decomposition of sodium perborate tetrahydrate to sodium perborate monohydrate and sodium metaborate were evaluated by model-free isoconversional method. The complex nature of multi-step process of sodium perborate tetrahydrate to sodium metaborate was more easily indicated by using wide temperature range in nonisothermal isoconversional method.     

Durable press finish of cotton/polyester fabrics with 1,2,3,4‐butanetetracarboxylic acid and sodium propionate

Sodium hypophosphite (SHP) is widely used as an effective catalyst for the esterification reaction of cellulose with 1,2,3,4‐butanetetracarboxylic acid (BTCA). However, catalysts containing phosphorus cause significant shade changes in dyed fabrics because of their reductive nature, and the effluents containing phosphorus cause eutrophication in rivers and lakes. Hence, their commercial application as catalysts in textile processing is limited. In this study sodium propionate and its catalytic activities as a nonphosphorous catalyst were investigated. The evidence for esterification and crosslinking of cellulose with BTCA in the presence of sodium propionate was shown by an improved wrinkle recovery angle and durable press rating of treated fabrics. The presence of ester groups in the treated fabrics was confirmed by FTIR analysis. The performance of sodium propionate as a catalyst for BTCA was comparable to that of SHP. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 654–661, 2001     

复分解法生产小苏打母液的综合处理

为了处理回收复分解反应生产小苏打过程的含氯化铵和氯化钠的母液,采用多效真空降膜蒸发、热泵等蒸发节能新技术,克服了热法回收氯化铵和氯化钠中设备腐蚀严重、能耗较高的技术难题,取得了热法回收氯化铵和氯化钠工艺的突破性进展,并成功应用于实际生产,达到了节能环保的目的。该技术也适用于其他含氯化铵和氯化钠溶液的处理。     

废旧涤棉混纺织物的循环醇解工艺研究

以经过致密化处理的废旧涤棉军装(废旧涤棉)为原料,以乙二醇(EG)为醇解剂,通过改变EG与废旧涤棉的配比、醇解时间、醇解液循环使用次数等研究了废旧涤棉的醇解效率,以及不同循环次数对醇解产物对苯二甲酸乙二醇酯(BHET)和涤棉织物中的棉纱性能的影响。结果表明:在废旧涤棉与EG质量比为1∶(10~12),废旧涤棉与Na_2CO_3质量比为1∶0.003,反应温度196℃,反应时间1 h的醇解条件下,醇解液可以循环使用,最佳循环使用次数为4,醇解后产物绝大部分仍为BHET单体,醇解物产率高于60%;醇解后棉纱表面虽有一定程度破坏,但其断裂强度最高仍达1.76 c N/dtex,满足开松再纺纱的要求,可实现棉纱的二次回收利用。     

真空氧等离子体表面改性涤纶织物研究

采用真空氧等离子体对涤纶织物进行表面改性,探讨不同处理压强、处理时间下织物润湿性能和分散染料染色性能的变化。使用X射线光电子能谱技术研究了织物表面处理前后化学组成及元素含量的变化,利用扫描电子显微镜表征了处理后织物表面形貌的变化。结果表明:真空氧等离子体处理后的涤纶织物表面氧元素的含量从24.1%上升到40.7%,表面粗糙程度提高;同时织物的润湿性能提高,润湿时间由1680s下降到51s;等离子体处理后涤纶织物的分散染料染色性能改善,其表面深度值由12.3增加为15.6,透湿量由2941g/(m~2·d)增加为3282g/(m~2·d)。     

饱和铬酸钠共存苛性碱中铬铁矿的氧化分解行为

为考察铬铁矿苛性碱氧化浸出反应体系循环苛性碱溶液对铬铁矿氧化分解行为的影响,以90℃下饱和铬酸钠共存苛性碱(代替单一苛性碱溶液)作为反应介质,研究了苛性碱浓度、氧气分压、铬铁矿粉粒度、反应温度、反应时间等参数对铬铁矿氧化分解过程的影响规律,分析了铬酸钠与苛性碱的分离效果以及铬酸钠与铝、硅杂质元素的分离效果。研究结果表明,铬铁矿氧化分解的较佳工艺条件为苛性碱浓度50wt%、氧气分压3.2 MPa、铬铁矿粒度小于48 μm、反应温度250℃、反应时间240 min。在较优工艺条件下,铬铁矿中铬元素的浸出率达到95.24%;铬铁矿中浸出的铬有96.36%以铬酸钠晶体的形式在后续浸出渣溶解分离过程中进入溶晶液,而铬铁矿中浸出的铝、硅分别有84.92%和95.04%进入到浸出液中;同时,未参与反应的苛性碱有89.41%保留在浸出液中。与苛性碱单一反应介质氧化分解铬铁矿的过程相比,本工作采用的反应方式将从铬铁矿中浸出的主元素铬、杂质元素铝和硅,以及未参与反应的苛性碱分别调整到溶晶液和浸出液中,获得了较好的分离效果。     

纳米羟基磷灰石在光催化聚酯织物上的应用研究

将纳米羟基磷灰石(HAP)溶于一定pH值(氨水调节pH值)的水中,制成HAP质量分数为1%的水分散体系;将聚酯织物浸泡于HAP的水分散体系中12 h,经清洗烘干后,再在纳米二氧化钛(TiO₂)质量分数1%的分散体系中浸泡12 h,浸轧后,再在120℃下焙烘2 h;通过对吸附HAP后的聚酯织物的结构和性能进行测试,研究了HAP在不同pH值水中的分散性能,以及HAP对紫外光照射聚酯织物的稳定性及对聚酯本身的保护性能。结果表明:在pH值为12.50时、HAP质量分数为1%的水分散体系中,HAP能均匀致密地分布于聚酯织物表面,并能有效结合;在紫外线强度10 000μW/cm²条件下照射2 h后,纳米TiO₂光催化剂能促进甲醛和聚酯织物的分解;纳米HAP对聚酯织物光催化分解的保护效果不明显。     

乙二醇分离回收废弃涤棉混纺织物

利用乙二醇(EG)对废弃涤棉混纺织物醇解分离,并对醇解工艺优化,使涤棉易于分离,实现循环利用。通过单因素实验,考察了EG与织物的质量配比、醇解温度、醇解时间等因素对醇解分离效果的影响。研究表明:当EG与涤棉混纺织物的质量配比为3∶1、过滤温度60℃以上时最利于过滤回收,较适宜的醇解温度为196~210℃,醇解时间为2.5 h。回收后的棉纤维物理机械性几乎没有损伤,可被重复利用。同时,回收的再生PET特性黏度可达0.65 dL/g以上,可以满足纺丝要求。     

Esterification kinetics of glycerol with fatty acids in the presence of sodium and potassium soaps

The kinetics of the direct esterification of glycerol with fatty acids in the presence of sodium and potassium soaps, synthesized in situ to obtain modified acylglycerol emulsifiers, were investigated. The effect of temperature, soap concentration and fatty acid hydrocarbon chain length on the concentration of monoacylglycerols in the reaction mixture was examined. The kinetic studies proved that esterification of glycerol with fatty acids by our method is a first order consecutive reaction with monoacylglycerol as stable intermediate product. The corresponding rate constants and activation energies were evaluated. With the known reaction rate constants, the maximum concentration of monoacylglycerol may be calculated. It was stated that the proposed method opens up possibilities for a specific adjustment of the acylglycerol composition and, thus, of the hydrophilic-lipophilic properties and the characteristics of the emulsifier.     

Enhanced adhesion of polypyrrole/PW12O hybrid coatings on polyester fabrics

Polyester fabrics have been treated with plasma to increase polypyrrole/PW₁₂O₄₀^3‐ (hybrid material) adhesion to its surface. With the plasma treatment, the roughness of the fibers increases as it has been observed by means of atomic force microscopy (AFM). Polar functional groups are also created on the surface of polyester fabrics as X‐ray photoelectron spectroscopy (XPS) measurements have shown. These polar groups contribute to the adhesion of polypyrrole to the fibers. Coatings obtained on plasma treated fabrics were more resistant to washing and rubbing fastness tests. The use of an inorganic counter ion (PW₁₂O) that contains an element with a high atomic number (W) helps to locate zones where the coating is missed; this is achieved by means of micrographs obtained by backscattered electrons (BSE). The electrical resistance of the fabrics was also measured by electrochemical impedance spectroscopy (EIS), obtaining also better results with the plasma treated fabrics. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Wash fastness of fluorocarbon finishes on polyester fabrics

A fabric's surface tension provides a measure of its ability to repel water and oil, while water penetration can be evaluated from a fabric's hydrostatic pressure, which depends mainly on the pore size and thus on the weave. One way of making a surface hydrophobic is to coat it with fluorinated polymers, which confer a low surface tension, reducing the fabric's wettability while preserving its breathability. We have shown that polyester microfibre fabrics (which already have a tight weave and hence high hydrostatic pressure) can be treated with fluorinated finishes to increase water and oil repellency. Observation of a piece of fluorinated polyester microfibre fabric over a number of washings has shown that a regenerative heat treatment preserved the repellency of the fabric but had little influence on the decrease in hydrostatic pressure that occurs with washing.     

Selective properties of polyester and cotton/polyester fabrics gamma radiation grafted with different binary mixtures of vinyl monomers

Radiation graft copolymerization of individual and comonomer mixtures of vinyl monomers onto polyester and cotton/polyester fabrics by the mutual method has been investigated. The effect of factors that may affect the grafting yield, such as solvent composition, comonomer mixture composition and radiation dose, have been examined. Suitable conditions that gives the highest graft yield without altering the original properties of the substrates are reported briefly. An attempt was made to determine the graft yield fraction from each monomer in the final graft copolymer in the case of grafting comonomer mixtures by using elemental analysis of nitrogen. Moreover, the results of elemental analysis were used to determine the reactivity ratios of the vinyl monomers. Some selective properties of the graft copolymers of polyester and cotton/polyester with the individual and comonomer mixtures have been investigated. The studied properties are the dye affinity for various dyestuffs and the mechanical properties in terms of tensile strength, elongation at break and Young's modulus. In general and regardless of the system used, grafting improves the dyeability of polyester and cotton/polyester with basic, vat, acid and disperse dyes. Also, it was found that improvement in dyeing and mechanical properties depends essentially on the composition of the graft copolymer and not on the composition of the feed comonomer solution or the total graft yield. © 1999 Society of Chemical Industry     

Modelling the properties of pigment‐dyed polyester/cotton sheeting fabrics by response surface methodology

The aim of this study was to model the effect of pigment, binder and fixer concentrations on the rubbing fastness, crease recovery, tear strength and stiffness of pigment‐dyed polyester/cotton sheeting fabrics. The design and analysis of experiments were carried out using Minitab^® statistical software according to the central composite design of response surface methodology. It was found that an increase in the binder concentration significantly improves the dry rubbing fastness, crease recovery and stiffness of the fabric, with a corresponding decrease in fabric tear strength, without significantly affecting the wet rubbing fastness. An increase in the fixer concentration significantly improves both the dry and wet rubbing fastness and crease recovery, with a decrease in fabric tear strength and stiffness. The effect of binder and fixer concentrations on crease recovery was not linear and there was significant negative interaction between these factors for dry rubbing fastness. The effect of pigment concentration was not found to be statistically significant for the types and range of concentrations of pigment, binder and fixer used in this study.