聚酰胺酸溶液的流变性能研究

采用锥板粘度计研究了聚酰胺酸溶液的流变性能及其粘度的影响因素。结果表明:聚酰胺酸溶液属于非牛顿假塑性流体,还具有负触变性流体的特征。聚酰胺酸溶液的粘度随剪切速率的增加而减小,随浓度的增加而增大,随温度的升高而降低,随存放时间的延长而下降;质量分数为15％的聚酰胺酸溶液的粘流活化能为20．83 kJ／mol。     

聚芳醚砜酮纺丝溶液流变性能研究

研究了含二氮杂萘酮结构聚芳醚砜酮 (PPESK)的 N-甲基吡咯烷硐 (NMP)溶液体系的粘度对浓度、温度和切变速率以及砜酮比的依赖性。结果表明 ,该溶液的粘度随剪切速率的提高而降低 ,为非牛顿流体 ;粘度随溶液浓度的增大而增大 ,与浓度的高次幂成正比 ,随砜酮比的增加而下降 ;温度对粘度的影响服从 Arrhenius公式。用该溶液纺制的纤维经测定力学性能较好。     

高相对分子质量PAN纺丝溶液的流变性质

研究了聚丙烯腈 (PAN )纺丝溶液的浓度、温度及聚合物相对分子质量对纺丝溶液的 lgηa ～lgγ流动曲线、粘流活化能、非牛顿指数和结构粘度指数的影响。结果表明 :高相对分子质量聚丙烯腈纺丝溶液具有明显的非牛顿性 ,结构粘度指数随纺丝溶液浓度的升高 ,PAN相对分子质量的增大而增大 ,随纺丝溶液温度的升高、聚合物相对分子质量和浓度的降低而减小。纺制高性能的高相对分子质量PA N纤维宜采用较低的溶液浓度和较高的纺丝温度。     

聚酰胺树脂醇溶液研制及防腐应用

制备一系列组成不同的聚酰胺树脂醇溶液,考察各种因素对其凝胶时间的影响,得出：采用不同溶剂合成的溶液,凝胶时间都溶质浓度的增大而缩短;加入不同抗交剂,可以延长凝胶时间;在合成过程中,提高反应温度,增加搅拌速度,会使溶液的凝胶时间缩短另外,测定了所制备产物的粘度,发现溶液粘度随浓度的增大而增大,并随温度的升高而降低。对合成产品做为金属防腐涂料进行实验,证明其具有良好的耐酸、耐碱、耐盐耐油等性能,支附着     

醋酸纤维素/壳聚糖纺丝原液的流变性能研究

采用锥板式旋转粘度计法对醋酸纤维素/壳聚糖共混原液的流变性能进行测定。结果表明,醋酸纤维素/壳聚糖共混原液无第一牛顿区,为非牛顿流体。随着剪切速率的加大,原液呈现切力变稀现象。温度在较大剪切速率范围内影响着原液的粘度,粘度随温度的上升而下降,但在高剪切速率区间,温度的影响很小。总体来说,粘流活化能?Eη随原液总固浓度的提高而降低,但在总固浓度为8%左右时出现了一个极大值。原液的结构化程度随体系温度上升、总固浓度下降而减小。     

壳聚糖复合材料对废水中汞离子的吸附

以壳聚糖为基质,通过化学键合方法制备了铝涂覆的壳聚糖-铝氧化物复合材料;发现其对水溶液中的汞离子具有较好的吸附性能,研究了反应温度、时间、溶液起始浓度等条件对吸附性能的影响;壳聚糖复合材料对汞离子的吸附量随反应温度的升高而增大,以化学吸附为主;随着溶液中离子的起始浓度的增大,吸附量迅速增加,而吸附率则下降;对于低浓度的溶液,常温下吸附率可达90%以上,而对于浓度较高的溶液,吸附量高达900 mg/g以上;与未改性的壳聚糖及无机氧化铝相比,壳聚糖复合材料对汞离子的吸附性能得到明显改善;壳聚糖经改性后,热稳定性也得到了显著提高.     

落葵多糖粘度影响因素的研究

本实验主要从落葵中提取而得的多糖进行粘度的研究,分别在不同的浓度、不同的温度、不同的pH值、不同的电解质溶液的条件下测定多糖溶液的粘度变化情况,从而得出对落葵多糖粘度影响较为显著的因素。结果：落葵多糖的粘度随温度升高而减小,随浓度、pH值增大呈锯齿状变化,不同电解质对其影响不同,其中随Na^＋浓度增大的变化比较不规则,随着心和Ca^2＋浓度的增大而变大,且随K^＋的变化幅度比较大,随Ca^2＋的变化比较平稳。     

明胶水溶液粘度影响因素分析

明胶具有粘性性能,可作为增稠剂应用于食品、医学、化妆品等行业。本文主要考察了明胶溶液的浓度对其溶液粘度的影响以及酸、碱、盐和放置时间对明胶溶液粘度的影响,确定影响明胶溶液粘度改变的主要因素。实验结果表明,明胶溶液的粘度受浓度影响很大。明胶溶液粘度随浓度的增加而升高;室温条件下,几乎不受放置时间的影响。在明胶溶液的等电点处,溶液粘度最小。随着溶液pH值的减小(或增大),溶液粘度均呈现先增大后减小的趋势。     

聚合物溶液流变曲线及粘温特性研究

用长庆油田北三区处理后清水、聚丙烯酰胺配制了聚合物母液和目的液,聚合物母液浓度5000mg/L、目的液浓度2000mg/L,测量温度为10~60℃,剪切速率为1~100s~(-1),考察了剪切速率、温度对不同浓度聚合物的流变性、粘度影响。结果表明,聚合物溶液的粘度随剪切速率的增大不断降低,同一剪切速率下聚合物溶液的表观粘度随温度的升高也有所下降,随着测量温度的升高,聚合物溶液的屈服应力逐渐降低,稠度系数K逐渐增大而流变行为指数逐渐减小,在实际测量温度范围内,聚合物溶液属于非牛顿流体,体现出典型的屈服-假塑性流体特性,剪切速率对聚合物溶液的粘度值影响很大,测量温度对粘度值的影响较小。     

非离子型X线造影剂粘度的研究

对常用的几种非离子型 X线造影剂的粘度进行了研究。结果表明 ,造影剂溶液的粘度 η(m Pa· s)随造影剂浓度 c(g I/ m L)的增加急剧增加 ,粘度与造影剂浓度的四次方呈线性关系 :η=a[c]4 +b;粘度随温度的上升而急剧下降 ;浓度越高 ,温度对粘度的影响越大 :η′=a′t+b′     

甲壳胺/乙酸溶液表观粘度的影响因素

在低剪切速率下,研究了甲壳胺的浓度、溶液静置时间、溶液温度及溶剂乙酸浓度对甲壳胺/乙酸溶液表观粘度的影响。结果表明:甲壳胺/乙酸溶液的表观粘度随甲壳胺浓度的增加而上升,随溶液温度的上升而降低,随乙酸浓度的增加有所降低。配制甲壳胺/乙酸纺丝原液时,需现用现配,甲壳胺质量分数4.5%,乙酸质量分数2.0%,溶液温度20℃为宜。     

壳聚糖改性疏水缔合聚丙烯酰胺的制备及表征

为了改善疏水缔合聚丙烯酰胺的溶解性以及溶液稳定性，本文采用巯基壳聚糖对疏水缔合聚丙烯酰胺进行改性，红外表征结果说明巯基壳聚糖连接到了聚丙烯酰胺分子链上。对影响壳聚糖改性实验的因素进行分析，实验结果说明，壳聚糖中巯基含量增大、壳聚糖加入量增大以及改性反应温度升高都会造成聚合物分子量降低，当改性反应的反应温度不高于35℃、添加壳聚糖质量不高于单体质量的3%时，得到的改性聚合物分子量满足现场使用要求。对改性聚合物的溶解性及溶液稳定性进行了评价，结果表明，壳聚糖中巯基含量增大及壳聚糖加入量增大对聚合物溶解性及溶液稳定性有明显的改善，聚合物的溶解时间由改性前的150min最多缩短至20min，聚合物溶液黏度保留率由改性前的60%最多提高到90%以上，壳聚糖改性有望弥补疏水缔合聚合物现场使用中的一些不足。     

微波条件下甲壳素脱乙酰反应的条件研究

研究了微波处理条件下,甲壳素脱乙酰反应条件对壳聚糖脱乙酰度的影响。结果表明:微波甲壳素颗粒大小选择为0.18～0.3mm(过60～80目筛)较利于反应。在料液比小于1∶12(质量∶体积)时,壳聚糖脱乙酰度几乎不变,粘度逐渐增大,之后脱乙酰度随料液比的增大而下降。脱乙酰度随碱液浓度的增大而增大。随微波处理时间的延长,脱乙酰度上升、特性粘度下降。微波功率越高,相同时间下,产品的脱乙酰度越高。经正交试验得出:粒度为0.18～0.3mm的甲壳素原料,按料液比1∶12(质量∶体积)加入浓度为50%(质量分数)的NaOH溶液,在微波功率320W下处理21min,所得产品的脱乙酰度可达85.65%,特性粘度为394.07mL/g,灰分为0.05%。     

纤维素纳米晶体对壳聚糖纺丝原液流变行为的影响

首先将纤维素纳米晶体(CNC)悬浮液进行超声分散,然后与壳聚糖乙酸溶液进行高速搅拌共混,制备不同CNC含量的壳聚糖-CNC共混均匀溶液。采用平板式旋转流变仪研究了CNC含量对壳聚糖溶液流变行为的影响。测试结果表明:壳聚糖-CNC共混溶液表现为非牛顿流体行为;黏度随温度的上升而下降,但在高剪切速率范围内,温度对黏度的影响不再明显;随着CNC含量的增加,壳聚糖溶液的表观黏度增大,对剪切速率的敏感性增强,同时非牛顿指数和黏流活化能降低;共混原液的结构黏度指数随CNC含量减少以及温度升高而降低;壳聚糖-CNC共混溶液储能模量和损耗模量的交叉点随温度的升高向高频区移动,随CNC含量的增加向低频区移动,溶液流变规律基本符合Cox-Merz规则。     

Variation in Properties of Chitosan Prepared at Different Alkali Concentrations from Squid Pen and Shrimp Shell

Chitin from squid pen (Loligo sp.) and kiddi shrimp shell (Parapenaeopsis stylifera) were treated at room temperature (30 ± 2°C) with four different concentrations of sodium hydroxide: 20, 30, 40, and 50% w/w. With 50% sodium hydroxide solution, within 108 h, the chitin from squid pen was deacetylated to give chitosan. But it required 126 h at 40% and 144 h at 30% concentration of sodium hydroxide. In the case of chitin from Parapenaeopsis stylifera, complete deacetylation took place after 120 h and 168 h at 50 and 40% concentrations of sodium hydroxide, respectively. But shrimp shell on treatment with 20 and 30% sodium hydroxide solutions and squid pen kept at 20% sodium hydroxide were not sufficiently deacetylated even after 480 h. Properties like degree of deacetylation, viscosity and molecular weight of the prepared chitosan samples were studied. Minimum alkali concentration required for the formation of chitosan at room temperature was found to be 30% for squid chitin and 40% for shrimp chitin. With the increase in the time of deacetylation, decreases in molecular weight and viscosity were observed in chitosan from both sources. Maximum viscosity was recorded by chitosan prepared from squid pen using 30% sodium hydroxide solution at room temperature.     

Effect of time/temperature treatment parameters on depolymerization of chitosan

Depolymerization of the biopolymer chitosan by an autoclaving process at 121°C and 15 psi was investigated using various treatments. Acetic acid was found to be the most effective solvent in decreasing chitosan viscosity among the six organic acids tested. The rate of viscosity decrease increased with increasing chitosan concentration. The viscosity of 1% chitosan in 1% acetic acid decreased rapidly to 91% of the initial viscosity following the initial 15 min of autoclaving. This decreased gradually to 93% and 94% in 30 and 60 min, respectively, without being adversely affected by the chitosan solution volume. The degree of deacetylation was comparable before and after autoclaving for 60 min. Chitosan at three molecular weights (M_r = 1597, 1110, and 789 kDa) decreased in molecular weight by 46%–51% in the 15‐min treatment, 55%–60% in the 30‐min treatment, and 60%–62% in the 60‐min treatment. The addition of 0.1%–1.0% (v/v) concentrations of hydrogen peroxide to the chitosan solution autoclaved for 15 min decreased viscosity by 94%–98% and molecular weight by 69%–83%. This process is a simple, timesaving, homogeneous depolymerization procedure, and it is possible to prepare partially hydrolyzed chitosan with specified molecular weights by regulating the time of treatment. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1890–1894, 2003     

Electrospinning of chitosan/poly(vinyl alcohol)/acrylic acid aqueous solutions

Chitosan bicomponent fibers were prepared via the electrospinning of chitosan/poly(vinyl alcohol)/acrylic acid aqueous solutions with different concentrations. With a 4% acrylic acid aqueous solution, when the chitosan/poly(vinyl alcohol) mass ratios were lower than 80/20, electrospinning nanofibers could be obtained. With a 90% acrylic acid aqueous solution, when the chitosan/poly(vinyl alcohol) mass ratios were less than 95/5, good nanofibers could be electrospun. The average diameter of the nanofibers gradually decreased, and its distribution became narrower as the poly(vinyl alcohol) concentration increased. Chitosan/poly(vinyl alcohol)/acrylic acid aqueous solutions could be electrospun at various concentrations by the adjustment of the chitosan and poly(vinyl alcohol) concentrations. The effects of the viscosity and conductivity of the blend solution on the morphologies of the fiber mats were also investigated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5692–5697, 2006     

HEC-AM接枝聚合物溶液性能的研究

采用氧化还原体系合成羟乙基纤维素-丙烯酰胺( HEC-AM)接枝聚合物,利用旋转黏度计对接枝聚合物溶液的增黏性、耐热性、耐盐性等进行测定.结果表明:在所测试的聚合物质量分数(W)范围内,HEC-AM的增黏性要高于纯的聚丙烯酰胺( PAM);当W( HEC-AM)大于0.8％后,HEC-AM的黏度增长迅速.在同一温度下,HEC-AM溶液黏度均较PAM溶液高,当温度升至80℃时,HEC-AM的黏度保留率为54.4％,PAM的为28％;在80℃下老化5d后,HEC-AM的黏度保留率为53.3％,PAM为22.7％,HEC-AM比PAM具有更好的耐热性和热稳定性.盐溶液的质量浓度提高,HEC-AM和PAM的黏度均降低,但HEC-AM的耐盐性较PAM好;并且在较高温度下,HEC-AM表现出较好的耐盐性.     

聚丙烯酸系增稠剂的合成及性能研究

以丙烯酸单体为原料,N-马来酰化壳聚糖为交联剂,过硫酸铵为引发剂,采用溶液聚合法制备聚丙烯酸系增稠剂。研究了交联剂浓度、中和度、温度、不同电解质对聚丙烯酸系增稠剂粘度的影响。实验结果表明:交联剂为0.4wt%,中和度为80mol%,0.5wt%该增稠剂凝胶溶液粘度可达54 200 mPa.s,但在温度升高或电解质存在的情况下,体系粘度降低。     

Application of chitosan solutions gelled by melB tyrosinase to water‐resistant adhesives

An investigation was undertaken on the application of dilute chitosan solutions gelled by melB tyrosinase‐catalyzed reaction with 3,4‐dihydroxyphenethylamine (dopamine). The tyrosinase‐catalyzed reaction with dopamine conferred water‐resistant adhesive properties to the semi‐dilute chitosan solutions. The viscosity of the chitosan solutions highly increased by the tyrosinase‐catalyzed quinone conversion and the subsequent nonenzymatic reactions of o‐quinones with amino groups of the chitosan chains. The viscosity of chitosan solutions highly increased in shorter reaction times by addition of melB tyrosinase. Therefore, in this study, the gelation of a chitosan solution was carried out without poly(ethylene glycol) (PEG), which was added for the gelation of chitosan solutions using mushroom tyrosinase. The highly viscous, gel‐like modified chitosan materials were allowed to spread onto the surfaces of the glass slides, which were tightly lapped together and were held under water. Tensile shear adhesive strength of over 400 kPa was observed for the modified chitosan samples. An increase in either amino group concentration of the chitosan solutions or molecular mass of the chitosan samples used effectively led to an increase in adhesive strength of the glass slides. Adhesive strength obtained by chitosan materials gelled enzymatically was higher than that obtained by a chitosan gel prepared with glutaraldehyde as a chemical crosslinking agent. In addition, the use of melB tyrosinase led to a sharp increase in adhesive strength in shorter reaction times without other additives such as PEG. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008