试样颗粒对天然橡胶丙酮抽出物的影响

依照标准GB/T 3516—2006,采用索氏抽提法测定不同形状、不同数目天然橡胶试样的丙酮抽出物,结果表明:试样表面积越大;径向尺寸越短,其质量分数值越高。长条形试样表面积较大;径向尺寸较短,又便于制取,其试样适合测定天然橡胶丙酮抽出物。     

复合橡胶溶剂抽出物的方法改进

优化索氏抽提法测定复合橡胶溶剂抽出物的方法进行改进。在测定方法 GB/T 3516-2006的基础上,研究试样形状、回流速率和抽提时间对三种不同成份的复合橡胶溶剂抽出物的影响。结果表明试样形状为细长条,回流速率控制在20次/h,抽提时间为20 h,溶剂抽出物质量分数最高。优化后的方法细化了试验因素,能够为测定标准的修订提升提供依据。     

木材和纸浆中树脂成分的抽提分离及分析

介绍了木材和纸浆中树脂成分的抽提、分离及现代分析方法。索氏抽提、超临界流体抽提、Soxtec抽提和固相抽提法可对木材或纸浆中树脂成分进行抽提。DEAE－SePhex离子交换色谱技术可以将抽出物分离成中性组分、弱酸性组分和强酸性组分．用于抽出物分析的现代分析技术主要包括气相色谱（GC）、高效该相色谱、凝胶渗透色谱（GPC）、薄层色谱（TL）、红外光谱（IR）和核磁共振光谱（NMR）等。     

芳纶Ⅱ纤维表面处理剂含量测定标准化及其测试条件的研究

以芳纶Ⅱ纤维作为探讨对象,采用索氏抽提法测量芳纶Ⅱ纤维中的表面处理剂含量。研究了氯仿、丙酮、甲苯三种萃取剂以及不同萃取温度和不同萃取时间对结果的影响。     

饲料中粗脂肪含量的测定研究

通过对国标法酸水解法进行研究,发现在提取过程中用亚麻布进行过滤处理后进行提取最终测得的脂肪含量与国标法中饲料粗脂肪含量的测定结果基本相同。运用该法检测饲料中粗脂肪含量,可避免索氏抽提法测定过程中的繁琐、试验时间长,降低了检验成本。同时,通过对索氏抽提法进行研究,得出在转移滤渣的双纸滤纸时用定量滤纸将其包住后再放入滤纸筒进行抽提,可以有效降低实验成本。为饲料中粗脂肪含量测定提供参考。     

硫化胶中橡胶油含量的测定

研究硫化胶中橡胶油含量的测定。采用溶剂抽提法得到硫化胶的抽出物,并对其抽出物进行硅胶柱层析,建立了硫化胶中橡胶油含量的测定方法。该方法测定的硫化胶中橡胶油质量分数最大相对标准偏差为2. 3%,回收率为88. 0%～104. 1%。该方法操作简便,重复性好,结果准确、可靠。     

耐热性汽车制动材料的研究

围绕耐热性汽车制动材料的研制，用索氏抽提法测定了双酚Ａ型苯并恶嗪中间体在路易斯酸和六次甲基四胺作用下树脂的固化程度，同时利用ＩＲ、ＤＴＡ、ＴＧＡ等测试方法研究了固化物的结构和热稳定性。制备了以该树脂为基体的制动材料，测定了制动材料的热膨胀性及摩擦磨损性能，结果表明，开环聚合酚醛树脂具有良好的热稳定性，其制动材料高温摩擦系数稳定，热恢复性良好，热膨胀小。     

多孔硝酸铵中包裹剂含量三种测定方法比较

多孔硝酸铵储存及运输过程中很容易发生结块,为减少多孔硝酸铵的结块,很多生产企业生产过程中会加入一定量的包裹剂,如今多孔硝酸铵中包裹剂含量已成为许多客户关注的主要质量指标之一。目前测定多孔硝酸铵中包裹剂含量的分析方法主要有索氏抽提法、分液后重量法和分光光度法,为探寻更适合生产企业不同场合的分析方法,选取不同包裹剂含量的多孔硝酸铵样本,通过试验从精密度、准确度、分析耗时等方面对比索氏抽提法、分液后重量法和分光光度法测定多孔硝酸铵中包裹剂含量的差异。试验结果表明：三种分析方法的准确度及精密度均可满足分析要求,测定结果一致性较好且无显著性差异;据三种分析方法的特点,产品出厂检验时可优先考虑采用分液后重量法和索氏抽提法,分光光度法可作为中间过程控制的首选分析方法。     

硫化促进剂对橡胶老化性能的影响(2) 各种硫化促进剂的影响

ZnDMDC的作用(之一) 如前所述,Craig和Scheele曾表明,在用秋兰姆(无硫黄)体系硫化天然橡胶的过程中,三分之二的秋兰姆会变成二甲基二硫代氨基甲酸锌(以下简称ZnDMDC)。Flercher一直很重视这方面的研究,他推断这无疑会赋予秋兰姆胶以优良的耐老化性能。他首先用丙酮将天然橡胶(白绉片)抽出,将存在于天然胶中的天然防老剂除去。取抽出     

天然橡胶中非胶组分的作用

综述了非胶组分中蛋白质、类脂物、丙酮溶物、水溶物、无机盐、酶类和细菌等组分的主要成分和含量及其对天然胶乳稳定性以及对天然橡胶生胶综合性能的影响,对天然橡胶的生产加工和科学研究具有理论指导意义。     

Focused Microwave (FMW) Extraction of Polycyclic Aromatic Hydrocarbons (PAHs) from Plant Bioindicators,Comparison with Classical Techniques

Extraction efficiencies of polycyclic aromatic compounds (PAHs) from spruce needles (Picea abies) obtained by recently introduced “focused microwave assisted (FMW) extraction” (i) and conventional methods represented by extraction enhanced by sonication (ii) and Soxhlet extraction (iii) were compared. n-Hexane:acetone (azeotropic ratio, 53.5 wt % of acetone) extraction mixture was used in all experiments. The influence of various parameters (extraction time, intensity of irradiation, moisture content) both on the recoveries of PAHs from spruce needles (Picea abies) and the amount of co-isolated matrix components potentially interfering within the determinative step was examined. The mean extraction efficiencies of PAHs obtained by FMW extraction and sonication were found to be lower (82 % and 75 %, respectively) compared the extraction in Soxhlet apparatus (equal 100 %).     

溶剂和提取方法对苍耳子油提取的影响(英文)

为了有效提高苍耳子油的提取效率,考察了提取溶剂和提取方法对其提取率的影响.在5种常用提取溶剂(乙醇、乙酸乙酯、丙酮、二氯甲烷和环己烷)中,采用索氏提取法时二氯甲烷的提取率最高,采用微波法时乙醇的提取率最高.另外,采用微波法提取的苍耳子油的得率略低于索氏提取法,但微波法的提取效率更高,提取时间节省近30倍,溶剂消耗节省2倍.综合考虑,微波法提取具有更大的优势.     

碳纤维表面浆料涂层索氏提取去除方法的研究

采用丙酮和石油醚索氏提取的方法,进行了碳纤维表面涂层去除的研究工作。利用AFM、SEM和XPS对碳纤维表面形貌、微观结构以及元素含量进行分析,并对碳纤维及其环氧复合材料的性能进行了表征。结果表明:碳纤维经丙酮抽提24 h,石油醚再抽提24 h后,纤维表面的涂层已完全去除,单丝拉伸强度略有降低,降低幅度为2.31%,但碳纤维/环氧树脂复合材料的界面剪切强度增加4.10%,层间剪切强度增加3.49%,表明该涂层去除方法具有较好的实验效果。     

Efficient Extraction of Fuel Oil Hydrocarbons from Wood

Abstract

Sequential cold (room temperature) extraction from aged contaminated wood samples (southern yellow pine) with acetone followed by n‐pentane (upon a 3–4 days of sample incubation with each solvent) yielded more than 90% analyte recovery for both ambient (natural moisture content) and water‐submerged wood, significantly exceeding the recoveries obtained with one‐step extraction using single solvents and/or their mixtures. By contrast, a much faster ultrasound/Soxhlet extraction led to a virtually complete analyte recovery while using a 1∶1 mixture of these two solvents. Evidence obtained indicates that a possible role for the first solvent, acetone (in addition to collection of loose analyte), is the removal of an aqueous barrier surrounding the strongly adsorbed hydrocarbon, thus enabling its extraction by the second (non‐polar) solvent. For larger analyte concentrations (>60 mg n‐hexadecane/g wood), the high‐affinity binding sites became saturated (yielding 5–10 mg unrecovered analyte/g wood), and then a single solvent was sufficient for a near‐quantitative extraction.     

Extraktion mit überkritischen Fluiden,mikrowellenunterstützte und Soxhlet-Extraktion zur Probenvorbereitung von Boden und Klärschlamm für die gaschromatographische Analytik der PCB

Supercritical Fluid Extraction, Microwave Assisted Extraction and Soxhlet Extraction for the Analysis of PCB's in Soil and Sewage Sludge The supercritical fluid extraction (SFE) was applied on the analysis of PCB's in soil and sewage sludge. Some questions concerning the performance of SFE were studied. With spiked samples and the modifier toluene put directly onto the sample the effect of a static extraction before the dynamic extraction step is described. It was found that matrices with a high content of total organic carbon show matrix effects in SFE, which was identified by calibration of the whole analytical process and eliminated by repeating the extraction. Two real samples were used to compare the SFE with soxhlet extraction and organic solvent extraction by means of microwave energy. The extracts were cleaned by column chromatography on aluminium oxide and silica gel modified with silver nitrate and afterwards analysed by GC-ECD and GC-MS (SIM mode). Soxhlet and SFE gave comparable results. The best extraction results were achieved by microwave assisted extraction with a solvent mixture of hexane/acetone 3:1.     

Comparison of experimental solvent extraction techniques to determine the apparent composition of solvent refined coal

The apparent composition of Kentucky 9/14 solvent refined coal (SRC) has been determined by two Soxhlet solvent extraction techniques and one ultrasonic bath extraction technique. Each Soxhlet method gave significantly different composition results. Further, neither Soxhlet method gave results which agreed with data from the ambient temperature ultrasonic bath extractions. A third Soxhlet method involving reverse sequential extraction was found to be unsatisfactory for routine quantitative use because of excessive solvent loss and the possibility of sample repolymerization.     

A rapid microwave‐assisted solvent extraction method for assessment of stabilizer concentration in crosslinked polydimethylsiloxane

Crosslinked polydimethylsiloxanes were prepared containing 0.05 to 0.2 wt % of either a phenolic antioxidant (Irganox® 1010) or a hindered amine stabilizer (Tinuvin® 144). The stabilizer concentration was assessed by HPLC and UV‐Vis spectroscopy of Soxhlet and microwave‐assisted solvent extracts. Almost complete recovery of stabilizer was achieved with Soxhlet extraction. High stabilizer recovery was achieved when acetone was used as the solvent in the microwave‐assisted extraction. HPLC was shown to be an efficient method for determining the concentration of Irganox 1010. For Tinuvin 144 the selectivity of both UV‐Vis spectroscopy and HPLC was poor, leading to imprecise evaluation of the antioxidant concentration. The loss of stabilizer by migration from polymer to hot water (75 and 95°C) was monitored for the systems stabilized with Irganox 1010 and the diffusion coefficient of the antioxidant in the polymer was determined. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2185–2192, 2004     

Removal of ungrafted monomer from polypropylene‐graft‐maleic anhydride via supercritical carbon dioxide extraction

The removal of spent initiator, excess initiator and unbound monomer from newly synthesized polypropylene‐graft‐maleic anhydride (PP‐g‐MA) has typically been carried out using Soxhlet extraction. Standard solvents used in the Soxhlet process are xylene, toluene, acetone or methanol. These chemicals are not only hazardous to some degree, but also lead to undesirable maleic anhydride (MA) ring opening. This paper establishes that supercritical carbon dioxide (scCO₂) extraction of residuals prevents anhydride ring opening and eliminates the need for post‐extraction vacuum‐drying of the copolymer product. An added benefit of this innovative process is that environmentally friendly carbon dioxide (CO₂) is used in place of harmful solvents. The successful extraction of the residuals is established by thermogravimetric analysis (TGA), whereas FTIR spectroscopy is used to compare the anhydride content of Soxhlet‐extracted PP‐g‐MA to that of scCO₂‐extracted copolymer. Polym. Eng. Sci. 44:1636–1641, 2004. © 2004 Society of Plastics Engineers.     

The extraction of natural cashew nut-shell liquid from the cashew nut (Anacardium occidentale)

In the two-stage recovery of natural cashew nut-shell liquid (CNSL) by solvent extraction, the overall yields from half-shells obtained by mechanical cutting and from chilled fragmented shells (to solidify the phenols) by manual processing are identical, indicating that no physical loss of phenolic material occurs in the mechanical process. At the first stage, prior to comminution, the yield from intact half-shells of mechanical origin is considerably less than that from manually processed shells due to extensive internal fracturing of the shell structure and greater solvent penetration in the latter case. Static solvent extraction of macerated shells gave the same yield as Soxhlet extraction, but the filtration stage was difficult and large volumes of solvent were required. Soxhlet solvent extraction or ultrasound/solvent extraction of manually processed shells at ambient temperature gave similar yields and economy in solvent usage. Both were much superior to mechanical agitation. By catalyzed decarboxylation of the recovered natural CNSL an almost theoretical yield (25%) of phenolic lipid rich in cardanol was obtained, which is considerably higher than that (10%) in the traditional recovery of technical CNSL by the hot oil bath industrial method. Natural CNSL contains a predominant amount of anacardic acid and represents a novel phenolic lipid source. Chemical reduction with air/aqueous hydrazine gave saturated natural CNSL. Polymerization of natural CNSL was effected in alkaline solution with paraformaldehyde. Part 27. Part 26, ref. 1.