硫氰酸钠法腈纶纺丝溶液流变性能的研究

使用毛细管流变仪对常规 PA N的 N a SCN溶液 (浓度为 12 .8% )的流变性能进行了研究。剪切速率 (γ)的对数与校正表观粘度η校 和孔口胀大比 (B)都呈线性关系 ,η和 B在毛细管中都表现出松弛的特征。粘流活化能 (Eη)随着毛细管长径比 (L /D )增加 ,先是下降很快 ,然后逐渐变缓 ,最后趋向平衡 ;随着γ的对数的增加 ,Eη线性下降。孔口胀大活化能 (EB)随γ和 L /D的变化规律与 Eη的类似 ,但它随着γ增加而增大 ,且其值较小     

添加填料的腈纶纺丝溶液流变性能的研究

采用自制的毛细管流变仪 ,对添加填料的硫氰酸钠法腈纶纺丝溶液的流变性能进行了全面的研究 ,结果表明 :随着纺丝溶液中填料含量的增加 ,样品的校正表观粘度 (η校 )、孔口胀大比 (B )、粘流活化能 (Eη)和孔口胀大活化能 (EB)都不断减小 ,而非牛顿指数 (n )则不断增大     

原液着色PMIA纺丝浆液挤出胀大特性研究

研究了采用原液着色法制备间位芳香族聚酰胺(PMIA)有色纤维的纺丝浆液的挤出胀大特性;测定了纺丝浆液的密度、浓度;采用重量法测定了挤出胀大比(B),讨论了B与毛细管长径比(L/D)、纺丝压力、纺丝温度、剪切速率(γ)等工艺条件的关系。结果表明:采用原液着色PMIA浆液纺丝时,B随着L/D和温度的增大而减小,随着压力和γ的增大而增大;纺丝时可通过提高压力来减少高温对纺丝成形的影响,还可通过增加滤布层数来减小B。     

杂环芳香族聚酰胺纺丝原液孔口胀大效应的研究

采用摄影法研究了杂环芳香族聚酰胺纺丝原液的孔口胀大效应。结果表明:杂环芳香族聚酰胺纺丝原液在喷丝头挤出时会发生孔口胀大现象,在纺丝原液比浓对数黏数为4.20 dL/g,温度20～65℃,挤出压力0.25～0.45 MPa,喷丝孔长径比为1～7,滤布层数为1的条件下,纺丝原液的孔口胀大比为1.089 0～1.344 8;纺丝原液的孔口胀大比随着原液温度的上升、毛细管长径比的增大和滤布层数的增加呈逐渐减小趋势,随着聚合物相对分子质量的增大和挤出压力的增加呈逐渐增大趋势;纺丝原液的孔口胀大活化能随挤出压力的增加而增大。     

EPDM/PP热塑性弹性体的制备及其流变特性

以聚丙烯(PP)和三元乙丙橡胶(EPDM)等为原料,采用完全动态硫化共混技术制备EPDM/PP热塑性弹性体(TPV),使用毛细管流变仪对TPV熔体的流变特性进行测试。分别研究了剪切速率、挤出温度对黏度、剪切应力和挤出胀大比的影响,以及不同条件下熔体流过毛细管口模时流速对压力降的影响。结果表明,TPV熔体是假塑性流体,其剪切应力随剪切速率增大而增大,随挤出温度的升高而降低;黏度随剪切速率和挤出温度的增大而降低;挤出胀大比则随剪切速率和挤出温度的增大而增大;毛细管口模的压力降也随流速和毛细管口模长度的增大而增大。     

高等级HDPE管材树脂毛细管流变性能研究

采用单管毛细管流变仪,在不同温度下对高等级高密度聚乙烯(HDPE)管材树脂的熔体流动行为进行了研究,考察了剪切应力(τ<,w>)、剪切速率(γ)、挤出胀大及温度之间的关系.结果表明,高等级HDPE管材树脂熔体的剪切流动基本上服从幂律定律;熔体的表观黏度(η<,a>)对温度的依赖性大致上符合Arrhenius方程;η<,a>随τ<,w>和γ的增加而非线性减小;挤出胀大比随温度的升高而下降,随γ的增加呈非线性增大.     

工业实用混炼胶流变行为的研究(二)

(二)挤出胀大行为出口弹性效应的一个表现是挤出胀大。它可用挤出物直径与口型直径之比来表示其程度,这个比值叫做挤出胀大比B(或称膨胀比)。对试样Ⅱa实验中,使用不同长径比(L/D=30、20、16)毛细管,画出了以温度为参变量的挤出胀大比(B)对切变速率的依赖关     

等径异长毛细管口模的聚丙烯流变性能研究

采用组合式转矩流变仪研究了聚丙烯(PP)熔体在等径异长毛细管流道(长径比L/D为20,30,40)的流变行为。结果表明,非牛顿指数随着长径比的增加而减小,即熔体的非牛顿性增强,剪切速率对黏度敏感性增加;熔体黏流活化能随剪切速率的增大而减小,表现为低剪切速率范围黏度对温度较敏感,其中又以L/D=30情况下的敏感性最高。     

分子量80万的PAN溶液流变性质的研究

使用毛细管流变仪对粘均分子量８０万ＰＡＮ的ＤＭＦ溶液（浓度８％）的流变性进行了研究。剪切速率（）的对数与表观粘度（η）的对数和孔口胀大比（Ｂ）的对数都呈现线性关系。η和Ｂ都表现出松弛特性，但松弛时间随和温度（Ｔ）而变化的规律并不相同，η和Ｂ的活化能随而变化的规律亦不相同。     

PP/MRP复合材料熔体挤出胀大行为的研究

采用熔体流动速率仪考察了温度、剪切应力、以及微胶囊红磷(MRP)含量对聚丙烯(PP)/MRP复合体系熔体挤出胀大比的影响。结果表明:PP/MRP复合体系熔体的挤出胀大比随着温度的升高而呈减小的趋势,随剪切应力的增加而显著增大,并且在185℃时,挤出胀大比与剪切应力之间基本符合线性关系;MRP含量增大,则PP/MRP复合体系熔体的挤出胀大比值呈减小的趋势。     

炭黑添加剂对PAN原丝性能的影响

用炭黑改性聚丙烯腈原丝制得了中孔率大大提高的活性炭纤维。考察了炭黑对聚丙烯腈——二甲基亚砜纺丝溶液粘度、可纺位及纺得纤维微观结构、元素组成、力学性能和热性能的影响。由于炭黑具有纳米级的位径和粗糙的表面，因此可均匀分散于聚丙烯腈溶液及纤维中并与聚丙烯腈大分子结合，使其溶液粘度，粘流活化能增大。结晶度减小，但对其热性能影响不大。     

Relationship of structure to properties of surfactants. 15 Isomeric sulfated polyoxyethylenated Guerbet alcohols

The properties at 25°C in aqueous 0.1M NaCl at the aqueous solution/air, aqueous solution/hexadecane, and aqueous solution/hydrophobic solid interfaces of two isomeric Guerbet alcohol-derived surfactants C₈H₁₇CH(C₆H₁₃)CH₂(OC₂H₄)₅SO₄Na, one in which the octyl and hexyl groups are both linear (L isomer), the other in which they are both highly branched (B isomer), have been investigated and compared in some cases with commercial sodium linear dodecylbenzene-sulfonate (LAS). The cmc value increases, the pC₂₀ value decreases, and the ΔG^o _ad value becomes less negative in the order: L isomer—B isomer—LAS. The minimum area/molecule at the aqueous solution/air interface increases in the order: LAS≪L isomer<B isomer. The L isomer is slightly more hydrophobic than the B isomer, and both are considerably more surface-active than LAS. The greater steric inhibition to micellization in the B isomer results in the lowest minimum surface tension. Both isomers have similar minimum interfacial tension values against hexadecane. Unusually small minimum area/molecule values for the two isomers at the aqueous solution/hydrophobic solid interface may indicate multilayer adsorption there. Both isomers are more efficient at reducing the contact angle than LAS. Mixtures of the B isomer with the corresponding unsulfated Guerbet alcohol show only weak interaction between the two. No synergism in surface (or interfacial) tension reduction efficiency or micelle formation exists at either the aqueous solution/air or aqueous solution interface but the mixture does show synergism in surface (or interfacial) tension reduction effectiveness, yielding a surface tension value of 28.2 dynes/cm, and an interfacial tension value of 0.1 dyne/cm against hexadecane. Draves wetting times increase in the order: B isomer<LAS<L isomer, and Ross-Miles initial foam heights decrease in the order B isomer ≈LAS>L isomer. Presented in part at the American Oil Chemists’ Society meeting in Cincinnati, May, 1989.     

水对PAN-DMSO溶液流变性能及纺丝成形的影响

研究了水对聚丙烯腈-二甲基亚砜(PAN-DMSO)纺丝溶液流变性能和初生纤维组成及双扩散系数的影响。随着水含量的增加,PAN-DMSO溶液的表观粘度有所下降,其流动性得以改善,粘流活化能下降,孔口胀大比变大。适量水的加入还降低了纺丝成形过程中溶剂、非溶剂的扩散速率,减少了纤维中水含量,有利于制备高性能PAN原丝。     

Effect of WC content on the microstructures and corrosion behavior of Ti(C,N)-based cermets

The influence of WC content on the microstructure and corrosion behavior of Ti(C, N)-based cermets in 2 mol/L nitric acid solution was studied in this paper. There exists typical core/rim structure in the cermets. The cores appear black or white, and the rim is divided into white inner rim and grey outer rim. The undissolved Ti(C, N) particles normally appear as black cores, while the white core, inner rim and outer rim are (Ti, W, Mo) (C, N) solid solution formed at different sintering stages. The inner rim and white core appear brighter atomic contrast than the outer rim and black core, which is attributed to their higher W and Mo content. The thickness of the inner rim increases with WC addition, but the grain size of core/rim phase becomes finer. Meanwhile, the amount of white cores increases and that of black cores decreases. WC is more easily oxidized and dissolved in the nitric acid solution, compared with Ti(C, N). Therefore, the degradation of inner rim phase and the white core becomes more considerable with the increase of WC content. Consequently, the corrosion rate of cermets increases and the corrosion resistance of Ti(C, N)-based cermets is deteriorated with the increase of WC content.     

Extraction and recovery of rhodamine B,methyl violet and methylene blue from industrial wastewater using D2EHPA as an extractant

The extraction behavior of cationic dyes namely rhodamine B (RB), methyl violet (MV) and methylene blue (MB) from industrial wastewater has been investigated using di-(2-ethylhexyl) phosphoric acid (D2EHPA) in hexane as a carrier. The extraction of cationic dyes increases with decreasing feed phase pH and increasing D2EHPA concentration in organic phase. The stripping percentage of dyes using acetic acid as the stripping agent from loaded D2EHPA was found to increase with increasing acid concentration. 98% stripping efficiency of dyes was achieved with 8.5 mol/L acetic acid solution at an organic:aqueous phase ratio (O/A) of 2:1. Parameters examined include D2EHPA concentration, effect of diluents, effect of pH, effect of initial dye concentration, equilibration time, and various stripping agents, aqueous to organic phase ratio in extraction and organic to aqueous phase ratio in stripping.     

聚合物-表面活性剂对油/水界面剪切粘度的影响

利用正交实验设计研究了聚合物A、石油磺酸盐B、表面活性剂C三种因素共存时对原油模拟油/水界面剪切粘度的影响。单因素实验表明,表面活性剂C使原油模拟油/水界面粘度降低,而聚合物A的存在则使油/水界面剪切粘度上升。而三种因素共存时,在实验条件下,表面活性剂C对油/水界面剪切粘度有一定的影响,聚合物A和石油磺酸盐B看不出有较大影响。因此,在聚合物-表面活性剂复合驱体系中,界面剪切粘度的变化主要取决于体系中表面活性剂的变化。     

基于PLIF的浸没撞击流反应器的混合特性

利用平面激光诱导荧光技术对水平两喷嘴液-液撞击流反应器内的浓度场进行定性和定量分析,用离析度(IOS)评价时均混合效果,得到不同操作条件下IOS值沿径向射流方向的变化规律,并与三喷嘴的情况进行对比. 结果表明,喷嘴间距L、喷嘴直径D和进口流量Q对反应器混合效果有重要影响,在水平两向撞击流中,当喷嘴直径和流量一定时,随喷嘴间距增大,IOS下降速度加快,最佳间距为L/D=3;当喷嘴间距和流量一定时,随喷嘴直径增大,IOS下降更快,下降到IOS=0.05所需距离不断减小,最佳喷嘴直径D=12 mm;当喷嘴直径和喷嘴间距一定时,随流量增加,IOS下降速度先增加后减小,最佳流量Q=500′10-3 m3/h. 三喷嘴撞击流与两喷嘴变化趋势一致.     

Simultaneous Absorption of Hydrogen Sulfide and Carbon Dioxide into di-isopropanolamine Solution

The simultaneous absorption of hydrogen sulfide and carbon dioxide into di-isopropanolamine (DIPA) solution was investigated in a 183 cm long, 2.72 cm OD wetted-wall column at atmospheric pressure. The influence of liquid flow rate, gas flow rate, temperature and liquid concentration on the absorption rate, overall gas-phase mass transfer coefficient and selectivity factor were studied at a constant gas feed ratio. The results show that the absorption rate of CO₂ increases rapidly with increasing liquid flow rate (the Reynolds number of the turbulent liquid film ranges from 2600 to 4350) but increases moderately with increasing gas flow rate (G = 18-91 L/min), indicating that it is liquid-phase mass transfer controlled. In contrast, the absorption rate of H₂S increases very slowly with increasing liquid flow rate but increases rapidly with increasing gas flow rate, indicating that it is gas-phase mass transfer controlled. The absorption rate of CO₂ also increases with increasing temperature (26-80°C) but H₂S absorption rate decreases with increasing temperature. When the concentration of DIPA solution increases from 0.2 to 2.6 mol/L, the absorption rate of both CO₂ and H₂S increases but with a larger rate of increase for CO₂ For selective H₂S removal, it is preferable to operate at low liquid and high gas flow rates, low temperatures and low DIPA concentrations.