Study of the influence of reaction conditions on the degree of substitution,intrinsic viscosity,and yield of oxidized cellulose acetate by factorial experimental design

A half‐fraction, two‐level, four‐factor factorial experimental design was used to study the effects of the acetic anhydride concentration, reaction temperature, reaction time, and sulfuric acid concentration on the degree of substitution, intrinsic viscosity, and yield of oxidized cellulose acetate (OCA). Oxidized cellulose containing 20% (w/w) carboxylic acid was used as the starting material. The data were fitted by multiple regression analysis with SAS software. The correlation coefficients obtained from plots of the predicted and observed values for the degree of substitution, intrinsic viscosity, and yield were 0.985, 0.993, and 0.991, respectively. Residual normal plots of the regression models showed a linear relationship. Lenth and main‐factor‐effect plots revealed an increase in the degree of substitution of OCA with an increasing concentration of acetic anhydride. The latter had no effect on the intrinsic viscosity and yield of OCA. An increase in the reaction temperature led to an increase in the degree of substitution and a decrease in the intrinsic viscosity and yield of OCA. The influence of the reaction time on the degree of substitution and intrinsic viscosity followed a trend similar to that observed with the reaction temperature, but the yield of OCA was unaffected. Increasing the concentration of sulfuric acid reduced the degree of substitution, intrinsic viscosity, and yield of OCA. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 696–705, 2005     

Surface activity of quaternary ammonium salts derived from jojoba oil

A number ofcis andtrans quatenary ammonium salts were synthesized from jojoba oil. All derivatives were found to be surface active agents, i.e., they reduced the surface tension to 35 dynes/cm⁻¹, at very low concentrations. The relationship between the surface activity and the molecular structure is discussed.     

十二烷基苯磺酸钠水溶液聚集性质的研究

用滴体积法测出十二烷基苯磺酸钠（ＳＤＢＳ）稀水溶液的表面张力；然后求出其临界胶束浓度（ＣＭＣ）。同时通过溶液的电导率、吸收光谱以及荧光光谱测定求出其ＣＭＣ。这样测出的ＣＭＣ值为１．２～１．６×１０－３ｍｏｌ／Ｌ，与文献值相符。也研究了部分水解的聚丙烯酰胺（ＰＨＰＡＭ）对ＳＤＢＳ聚集性质的影响；发现ＳＤＢＳ的ＣＭＣ值随ＰＨＰＡＭ的加人而减少并且ＰＨＰＡＭ水溶液的粘度随ＳＤＢＳ的存在而急剧降低（类似盐效应）。这些方法与性质对强化采油（ＥＯＲ）是重要的。     

Dielectric investigation of isotropic and anisotropic solutions of cellulose acetate in dioxane

The dielectric and optical characteristics of a sample of cellulose acetate (DS = 2.45) in dioxane solutions were studied at 10–50°C of concentration 10–50 wt% to include both isotropic and anisotropic phases. The study showed that the loss maximum, ε_max″, magnitude of polarization, (ε₀ ? ε_∞), static dielectric constant, ε₀, time of relation, (2πf_m)^?1, and refractive index, n_D, steadily increase with concentration up to the critical concentration (41 wt%) and then decrease. The mean-square dipole moment, 〈gμ²〉, decreases steadily up to the critical concentration then remains nearly constant, indicating that the isotropic solution changes to anisotropic, with smaller mean-square dipole moment. Comparison between the results of cellulose acetate (CA) and those of hydroxypropyl cellulose (HPC) reveals that, at the critical concentration in dioxane, the cholesteric structure of HPC possesses a greater mean-square dipole moment with higher temperature coefficient than does CA. The activation energy of the relaxation process for hydroxypropyl cellulose is higher, indicating a greater intrachain interaction compared with cellulose acetate.     

乙酸纤维素的应用及改性研究现状

随着污染问题及资源短缺问题的日益严重,乙酸纤维素作为纤维素的重要衍生物之一,具有良好的加工性能及可生物降解性能,近年来一直备受关注。本文系统介绍了乙酸纤维素在服装纺织、烟用滤嘴及膜材料等方面的应用,分析了目前乙酸纤维素应用中存在的问题。同时从共混改性、纳米及纳米复合改性、表面改性等方面对乙酸纤维素的改性技术的研究进展进行了综述,最后展望了乙酸纤维素的发展前景,指出开发简单易行能够工业化的改性技术及制备出可再生的生物降解材料研究是乙酸纤维素改性今后的主要发展方向。     

十二烷基苯磺酸钠表面张力的研究

通过表面张力的测定,研究了浓度、温度对溶液表面张力的影响,同时考察无机盐浓度对溶液表面张力的影响.结果表明:十二烷基苯磺酸钠溶液表面张力随浓度的增加、温度的升高和无机盐浓度逐渐的增大而降低,最终确定其CMC值为1.47×10-3mol/L,由于键能和水合离子半径的原因,NaCl对十二烷基苯磺酸钠表面张力的影响明显于KCl.     

异辛基酚聚氧乙烯醚/十二烷基溴化吡啶混合溶液的表面性质及各组分含量的测定

对不同组成的异辛基酚聚氧乙烯醚(TX-100)和十二烷基溴化吡啶(DDPB)混合表面活性剂在KH2PO4/Na2HPO4缓冲溶液中的表面性质进行了研究,结果表明TX-100和DDPB间存在着较弱的作用。研究结果证实利用高效毛细管电泳法能够较准确地测定该混合体系中各单组分表面活性剂的含量;并能将该方法用于测定TX-100和DDPB的临界胶束浓度。     

Morphology of polyethylene blended with thermotropic hydroxyethyl cellulose acetate

Morphology of low-density polyethylene (PE)/thermotropic hydroxyethyl cellulose acetate (HECA) blends, and the melting and crystallization behavior of PE in the blends were studied. The “sea island” morphology was observed in PE/HECA blends. The process of melting and crystallization of PE in blends was independent of the HECA fraction when the PE fraction was larger than 50 wt %. When the PE fraction is smaller than 20 wt %, however, multiple crystallization was observed in the low temperature region. HECA was incompatible with PE crystals in the blends, but partially compatible with the amorphous part of PE. HECA could exist between the PE lamellae in PE spherulites, and concentric ring morphology was observed in spherulites. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1285–1291, 1998     

Toughening of epoxy resin blended with thermotropic hydroxyethyl cellulose acetate

Thermotropic hydroxyethyl cellulose acetate (HECA) was totally miscible with uncured epoxy resin, and the miscibility was not influenced by the degree of substitution (DS) of HECA. When the epoxy resin was cured with diamine (DDA), HECA became immiscible with the epoxy resin matrix, and a heterogeneous system was formed. Epoxy resin existed as a constant phase, and HECA-rich domains were dispersed in the matrix with dimensions of about 0.2–0.5 μm. Epoxy resin could be toughened by HECA, and the impact strength of the epoxy resin blends with 10 wt % HECA was the maximum. HECA exhibited the highest toughening ability when the epoxy resin was cured at the temperature at which the HECA existed as a liquid crystalline state. The toughening ability was also influenced by the degree of substitution for acetyl of HECA, and the impact strength of the epoxy resin blends decreased with increasing the DS for acetyl of HECA. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 1159–1163, 1998     

OMR的合成及与其他表面活性剂混合溶液的表面性质

用酯交换甲酯化法合成出蓖麻油酸甲酯,将分离出的蓖麻醇酸甲酯与环氧乙烷反应,得到蓖麻醇酸甲酯乙氧基化物(OMR,EO平均数为10)。OMR及其与其他表面活性剂混合溶液的表面张力曲线表明,OMR分子在气液界面上的吸附和排布比较特殊,导致它的γCMC较大,为36.78 mN/m;但较大的分子结构也使它有比较低的CMC,为4.58×10-5mol/L。OMR与AEO9的混合溶液近似于理想溶液,其表面张力和CMC介于二者之间;OMR的加入能够使SDS的CMC降低近2个数量级,但混合溶液的协同作用不强;OMR与CTAB有很强的协同作用,混合溶液的表面张力曲线出现最低点,其γCMC值最小可达28.24 mN/m,远小于OMR的36.78 mN/m和CTAB的36.62 mN/m,混合溶液的CMC最低为2.80×10-5mol/L,亦低于OMR的CMC。     

磺酸型Gemini表面活性剂的合成及表面活性

以壬基酚、1,4-二溴丁烷和氯磺酸为主要原料,通过三步反应合成了新型的磺酸型Gemini表面活性剂9BA-4-9BA,讨论了合成反应时间、温度以及催化剂对产物纯度和产率等因素的影响,优化了反应过程。利用核磁共振谱和红外光谱表征了产物结构,并通过DCTA21表面/界面张力仪测试其水溶液中的表面张力。和传统表面活性剂相比,合成的Gemini表面活性剂9BA-4-9BA具有更高的表面活性,其临界胶束浓度和C20分别为6.2×10-4mol/L和1.1×10-5mol/L。     

Effect of concentrated sulfuric acid and nitroethane on insoluble residues in acetylating medium of cellulose acetate prepared from low grade pulps

Cellulose acetate was prepared from locally available low grade pulps containing α‐cellulose in the range of 79–94%. The chemical and spectroscopic characterization confirmed the acetylation of all the cellulosic sources studied in the work. The effect of concentrated sulfuric acid as a catalyst and nitroethane as a solvent in the acetylation medium in reducing the insoluble residues was studied. The gravimetric analysis has indicated that these reagents reduce the insoluble residues. This was further confirmed by the optical microscopic photographs. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1765–1771, 2005     

Tailoring surface properties of cellulose acetate membranes by low‐pressure plasma processing

The aim of this study was to tailor the surface properties of cellulose acetate membranes using low‐pressure plasma processing. Argon (Ar) plasma and Difluoromethane (CH₂F₂) plasma were used to control the surface wettabilities of cellulose acetate membranes. Optical emission spectroscopy was used to examine the various chemical species of low‐pressure plasma processing. In this investigation, the plasma‐treated surfaces were analyzed by X‐ray photoelectron spectroscopy, while changes in morphology and surface roughness were determined with confocal laser scanning microscopy. Ar plasma activation resulted in hydrophilic surface. CH₂F₂ plasma deposited hydrophobic layer onto the cellulose acetate membrane because of strong fluorination of the top layer. The results reveal low‐pressure plasma processing is an effective method to control the surface properties of cellulose acetate membranes. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

皂荚素及其复配体系表面活性的研究

系统地研究了皂荚素单组份及其复配体系在常温下的来得及面张力及泡沫性能,以及温度、盐度、水硬度、pH值等因素对其表面活性的影响。结果表明皂荚素是一种性能优良的天然表面活性剂,具有强的耐盐和耐硬水能力,与其他常见的几种阴离子、阳离子、非离子型表面活性剂复配后,均具有显著的协同剂应。     

季铵盐型阳离子型表面活性单体AMC16AB胶束化行为的研究

本文对季铵盐型阳离子表面活性单体2-丙烯酰胺基乙基十六烷基二甲基溴化铵（AMC16AB）的胶束化行为进行了深入的研究。使用紫外分光光度法测定了AMC16AB在水中的溶解度；同时采用表面张力法（环法）和电导滴定法测定其临界胶束浓度（CMC）及在浓度为CMC时的表面张力（γoc）。采用荧光探针法测定了不同浓度时（C〉CMC）AMC，6AB的胶束聚集数Nagg；并研究了AMC16AB浓度和外加盐浓度对Nagg的影响。实验结果表明表面活性单体AMC16AB在水中的溶解性强，但降低水表面张力的能力差，即表面活性差；与结构相同的一般表面活性单体相比，AMC16AB的CMC较低，Krafft点较低；AMC16AB的Nagg随浓度的增大而逐渐变大，随外加盐浓度增加开始时变化不大，当外加盐浓度达到临界值C★时，其胶束聚集数迅速增大。这些因素对AMC16AB胶束化行为的影响规律与普通的表面活性剂相似。     

一种含全氟壬烯基硅表面活性剂的制备

研究了2-甲基-2-全氟壬烯氧基乙氧基羰基乙基甲基二聚乙氧基硅烷(Ⅴ)的制备方法和表面活性。以甲基丙烯酸-2-全氟壬烯氧基乙基酯(Ⅰ)和甲基二氯硅烷(Ⅱ)为原料,在氯铂酸催化下经过硅氢化反应得到2-甲基-2-全氟壬烯氧基乙氧基羰基乙基甲基二氯硅烷(Ⅲ),Ⅲ与聚乙二醇(Ⅳ)缩合反应得到非离子表面活性剂Ⅴ。用FTIR和MS对其结构进行了表征,优化了硅氢化反应工艺条件,测试了Ⅴ水溶液的表面张力和临界胶束浓度(CMC)。中间体Ⅲ的较优合成条件为:以四氢呋喃为溶剂,n(Ⅰ)∶n(Ⅱ)=1∶1.2,50℃下反应24 h,收率68.0%。表面活性剂Ⅴ水溶液的临界胶束质量浓度为0.22 g/L,此时的表面张力为19.5 mN/m,表明Ⅴ是高活性氟硅表面活性剂。     

Chemical modification of cellulose acetate by allylation and crosslinking with siloxane derivatives

A new pathway to cellulose–siloxane hybrid materials was investigated. Allylated cellulose was prepared by chemical modification of cellulose acetate using three different procedures and was crosslinked afterwards by hydrosilylation in the presence of Karstedt's catalyst. Poly[dimethyl(methyl‐H)siloxane] with 25 mol% Si? H side groups and 1,1,3,3‐tetramethyldisiloxane were used as crosslinking agents in different ratios as regards the unsaturated component. The occurrence of the reaction was verified using Fourier transform infrared spectrometry following the reduction until disappearance of bands corresponding to Si? H and C?C bonds with the formation of new Si? C bonds that led to the crosslinking of the cellulose derivative. The reaction products were processed as films that were insoluble in common solvents. Surface (static contact angle, water vapour sorption capacity and swelling in various solvents), mechanical and thermal properties of the networks processed as films were investigated and the results were correlated with the reactant ratios. The crosslinking density was determined based on differential scanning calorimetry data. Copyright © 2012 Society of Chemical Industry     

一种氟硅表面活性剂的合成及其表面活性

研究了2-甲基-2-全氟-2'-甲基-3'-氧代己酰氧基乙氧基羰基乙基甲基二聚氧乙烯基硅烷(Ⅴ)的制备方法和表面活性。以甲基丙烯酸-2-全氟-2'-甲基-3'-氧代己酰氧基乙基酯(Ⅰ)和甲基二氯硅烷(Ⅱ)为原料,0.5%Karsted催化剂存在下(以Ⅰ的质量计),发生硅氢化反应,得到2-甲基-2-全氟-2'-甲基-3'-氧代己酰氧基乙氧基羰基乙基甲基二氯硅烷(Ⅲ)。Ⅲ与聚乙二醇(Ⅳ)缩合反应得到非离子表面活性剂Ⅴ。用FTIR和MS对其结构进行了表征,优化了硅氢化反应工艺条件,测试了Ⅴ溶液的表面张力、临界胶束浓度(CMC)和处理玻璃后的疏水性能。以四氢呋喃为溶剂,中间体Ⅲ的较优合成条件为:n(Ⅰ)∶n(Ⅱ)=1.2∶1,50℃下反应28 h,化合物Ⅱ的转化率可达到68.2%。表面活性剂Ⅴ水溶液的CMC为0.52 g/L,临界表面张力γ_(CMC)为22.8 m N/m,用V的THF溶液处理玻璃后,玻璃表面具有很好的疏水性和较好的疏油性。     

Morphology and mechanical properties of nanocomposites of cellulose acetate and organic montmorillonite prepared with different plasticizers

Nanocomposites of cellulose acetate and an organically modified montmorillonite (CA/MMTO) were prepared by melt intercalation in a twin‐screw extruder, using two different plasticizers: di‐octyl phthalate (DOP) and triethyl citrate (TEC). The influence of plasticizer type and the organoclay added to the structure, the morphology, and the thermal properties of the nanocomposites was investigated. XRD and SAXS results indicated a significant CA or/and plasticizer intercalation in the clay gallery for the CA/MMTO nanocomposites. In addition, the images obtained by TEM show that the morphology of CA/MMTO nanocomposites is made up of intercalated and exfoliated silicate layers. The glass transition temperature (T_g) of CA with DOP or TEC decreased in at almost same value, which shows the characteristics of both additives as plasticizers for cellulose acetate chains. Tensile tests indicate that the nanocomposites with either of the two plasticizers presented the same performance with respect to material properties. The results demonstrated that, for some applications, TEC is an useful alternative to plasticize CA in order to substitute DOP, a non eco‐friendly plasticizer. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Characterization of glow‐discharge–treated cellulose acetate membrane surfaces for single‐layer enzyme electrode studies

Cellulose acetate membranes (CA) were modified by means of plasma polymerization of ethylene diamine (EDA) and n‐butylamine (n‐BA). The motivation for this work was the application of a modified membrane for the single‐layer enzyme electrode. A tubular reactor with the external radiofrequency (13.56 MHz) excitation was used. Surface modification was performed at 5, 10, and 15 W power (at 27 Pa working pressure) for 5, 10, 15 min. Modified surfaces were characterized in detail by FTIR–ATR, XPS (ESCA), contact angle, and enzyme immobilization activity. The best treatment results were obtained for EDA with 5 W and 30 min and 15 W and 10 min. These results are discussed using surface analysis data. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1341–1352, 2001