侧链结构对聚羧酸盐减水剂性能的影响

以丙烯酸、甲氧基聚乙二醇丙烯酸酯、烯丙基磺酸钠为原料,分别制备引入羧基侧链、引入聚氧乙烯侧链以及同时引入羧基与聚氧乙烯侧链的聚羧酸减水剂.加入水泥净浆性能测试结果表明,羧基侧链对减水剂的分散性能影响较大,聚氧乙烯侧链对减水剂的保塑性能影响较大,同时具有两种侧链的减水剂的分散性能和保塑性能都得到提高.     

SAS/MAA/MPEGMAA聚羧酸盐分散剂的制备与性能

以甲基丙烯酸(MAA)和4种不同侧链长度的甲氧基聚乙二醇(MPEG相对分子质量分别为350,500,750,1000)先聚合得到酯化大单体(MPEGMAA),再以甲基丙烯酸,烯丙基磺酸钠(SAS)为单体,在引发剂过硫酸钾,阻聚剂对苯二酚作用下聚合得到4种具有不同侧链长度的聚羧酸盐分散剂。通过红外(FT-IR)、核磁共振氢谱(1H NMR)和凝胶渗透色谱(GPC)对聚合物的结构、相对分子质量及其分布进行了表征和分析,并将其作用于彬长煤制浆,考察了浆体的表观黏度、流变性、zeta电位、吸附性以及最大成浆浓度和稳定性,测定其与煤的接触角,并通过X射线光电子能谱(XPS)分析,得出煤粒表面吸附分散剂后的吸附层厚度为6.12 nm。结果表明,侧链长度为SAS/MAA/MPEGMAA750的聚羧酸盐分散剂具有良好的润湿和吸附效果,对彬长煤具有更好的降黏、分散和稳定作用。     

嵌段聚羧酸侧链长度对水泥浆体分散性能的影响

采用可逆加成-断裂链转移聚合成功制备了主链与侧链重量比相一致,重均分子量相当的,仅侧链长度不同的嵌段结构聚羧酸(PC)。系统的研究了不同侧链长度的嵌段结构PC对水泥基材料分散性能、吸附性能以及溶液构象的影响规律,结果表明:随着侧链长度的增加,嵌段PC在水泥表面的吸附量增加,流体力学半径变大,蜷缩的溶液构象导致其在水泥基材料表面单位占有面积减小,因而其对水泥的分散性能呈现先增加后减小的趋势。     

SAS/MAA/MPEGMAA聚羧酸盐分散剂的制备与性能

以甲基丙烯酸（MAA）和 4 种不同侧链长度的甲氧基聚乙二醇（MPEG相对分子质量分别为350,500,750,1000）先聚合得到酯化大单体（MPEGMAA）,再以甲基丙烯酸,烯丙基磺酸钠（SAS）为单体,在引发剂过硫酸钾,阻聚剂对苯二酚作用下聚合得到 4 种具有不同侧链长度的聚羧酸盐分散剂。通过红外（FT-IR）、核磁共振氢谱（¹H NMR）和凝胶渗透色谱（GPC）对聚合物的结构、相对分子质量及其分布进行了表征和分析,并将其作用于彬长煤制浆,考察了浆体的表观黏度、流变性、zeta电位、吸附性以及最大成浆浓度和稳定性,测定其与煤的接触角,并通过X射线光电子能谱（XPS）分析,得出煤粒表面吸附分散剂后的吸附层厚度为 6.12 nm。结果表明,侧链长度为SAS/MAA/MPEGMAA750的聚羧酸盐分散剂具有良好的润湿和吸附效果,对彬长煤具有更好的降黏、分散和稳定作用。     

梳形共聚物分散剂侧链长度对水泥浆体分散性能的影响及机理

合成了系列具有不同侧链长度的梳形共聚物,并研究了共聚物侧链长度在不同水灰比条件下对水泥浆体分散、流变和ζ电位的影响规律,同时结合吸附性能,对添加梳形共聚物的水泥浆体粒子间作用能进行了计算.结果表明:含有较高吸附基团的短侧链梳形共聚物具有静电捧斥和空间位阻两种效应,其分散性能受水灰比影响较大;相反地以空间位阻效应为主的长侧链聚醚梳形共聚物则对水灰比体现出了良好的适应性.同短侧链梳形共聚物相比,长侧链聚合物由于具有较大的第二最小值(Vmin)和较长的平衡距离更适合于在浓悬浮体系中用作高性能分散剂.     

洗涤剂中聚羧酸盐对环境的影响

聚羧酸盐（ＰＣＡ）是无磷洗涤剂中的一种辅助剂。对其出现的历史背景,在洗涤剂中的主要作用,在水中的跟踪分析,及其对环境的影响进行了综述。     

端羟基双子季铵盐对聚羧酸盐减水剂抗泥性能的影响

以1,4-对二氯苄为连接基团，分别以三乙胺和N,N-二甲基乙醇胺为头基，合成了具有不同端基的双子季铵盐（分别标记为KNJ-1和KNJ-2）。将其作为抗泥剂与聚羧酸盐减水剂复配以改善粘土对减水剂的负面效应，探究端羟基的引入对抗泥效果的影响。通过FT-IR和1H NMR对其进行结构表征。净浆流动实验考察抗泥剂的对流动度的影响，并结合XRD、XPS和 Zeta电位分析其与蒙脱土的作用机理。实验结果表明：与KNJ-1相比，加入0.3‰KNJ-2使水泥净浆初始流动度提高了35mm, 2h后流动度提高了165mm,表现出更好的抗泥效果。XRD和 XPS结果表明KNJ-2在蒙脱土的表面和层间吸附均优于KNJ-1，Zeta电位结果显示KNJ-2的加入使表面电位从初始的-15.67mV上升到-0.15mV。表明羟基可通过氢键作用优先吸附在蒙脱土的表面和层间，占据大量活性位点，减少了对聚羧酸盐减水剂的吸附，保障减水剂的高效分散能力，从而达到对粘土抑制的效果。     

聚羧酸盐在浇注料中用作抗絮凝剂的影响

聚羧酸盐减水剂(PCE)是耐火材料中非常有效的分散剂。铝酸钙水泥在极低加水量条件下仍可被聚羧酸盐分散,而用普通的聚丙烯酸酯是无效的。浇注料的流动性和硬化性能受聚合物分子结构的影响。可以结合适量的活性氧化铝,根据具体要求调整浇注料的流动性和硬化性。因此,聚羧酸盐是制备高强型耐火材料必不可少的成分。本文描述了聚乙醚对水泥结合的铝酸钙自流浇注料和灰泥以及低水泥浇注料(LCC)的作用,并讨论了活性氧化铝对浇注料流动性和硬化性能的影响。     

烷基酚聚氧乙烯醚亲水链长度对水煤浆性能的影响

以烷基酚聚氧乙烯醚(APEO)为水煤浆添加剂,在不添加稳定剂的情况下,采用粘度分析法研究了APEO亲水链长度对5种不同煤所制得水煤浆的分散降粘作用的影响. 结果表明,当APEO的亲水亲油平衡值为18.5±0.4,即APEO的聚氧乙烯加成数(EO数)为60~100时,所得水煤浆浆体的表观粘度出现最低值,再增加或降低EO数,成浆性能下降. 不同APEO对应的最佳EO数不同,烷基链较短的对应较短的亲水链,烷基链较长的对应较长的亲水链. 烷基碳原子数为7, 9, 12, 14, 16, 18时,对应的最佳EO数分别为60, 60, 70, 80, 90和100.     

端羟基双子季铵盐对聚羧酸盐减水剂抗泥性能的影响

以1,4-对二氯苄为连接基团,分别以三乙胺和N,N-二甲基乙醇胺为头基,合成了具有不同端基的双子季铵盐(标记为KNJ-1和KNJ-2)。将其作为抗泥剂与聚羧酸盐减水剂复配,以改善蒙脱土对减水剂的负面效应,探究了端羟基的引入对抗泥效果的影响。通过FTIR和¹HNMR对其进行了结构表征。净浆流动实验考察抗泥剂的掺量对流动度的影响,并结合XRD、XPS和Zeta电位分析双子季铵盐与蒙脱土的作用机理。实验结果表明:与未掺抗泥剂的水泥相比,加入质量分数0.3‰KNJ-2使水泥初始净浆流动度提高了35 mm,2 h后流动度提高了175 mm,表现出显著的抗泥效果。XRD和XPS结果表明,KNJ-2在蒙脱土的表面和层间吸附均优于KNJ-1;Zeta电位结果显示,KNJ-2的加入使蒙脱土表面电位从初始的–15.67 mV上升到–0.15 mV。表明羟基可通过氢键作用优先吸附在蒙脱土的表面和层间,占据大量活性位点,减少了对聚羧酸盐减水剂的吸附,保障了减水剂的高效分散能力,从而达到对蒙脱土负面影响抑制的效果。     

分散剂结构对水煤浆性能的影响

介绍了水煤浆和常见分散剂的特点,阐述了制备高浓度水煤浆的影响因素、分散剂同煤粒的作用机理,重点综述了分散剂结构对水煤浆性能产生的影响和规律。另外,给出了理想分散剂可能具有的结构以及合成它的一些建议。     

Effects of chemical structure on the properties of carboxylate-type copolymer dispersant for coal-water slurry

In this study, a series of carboxylate-type copolymer dispersants were prepared. The effects of chemical structures of the copolymer dispersants, including the molecular weight, kind, quantity and ratio of hydrophilic/hydrophobic groups, and side chain length, on the solid loading, apparent viscosity, zeta potential, rheological behavior, and stability of coal-water slurry (CWS) prepared from Dongtan, Yima, and Datong coals were systematically investigated. The dispersion performance of the copolymer can be improved by adjusting its chemical structures, and the dispersion mechanism was discussed. In addition, a high solid loading CWS with excellent stability toward settling can be achieved by means of the copolymer dispersant and carboxymethyl cellulose sodium salt (CMC-Na). Experiments have proved that the copolymer has the potential to be developed as a new high-effective dispersant for CWS. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

β-环糊精侧链对聚羧酸减水剂抑制蒙脱土的影响

采用水泥净浆和混凝土试验,详细研究了β-环糊精侧链对聚羧酸减水剂抑制蒙脱土负效应的影响。试验表明,与仅含有聚氧乙烯侧链的传统聚羧酸减水剂相比,蒙脱土对掺加含有β-环糊精侧链的聚羧酸减水剂水泥净浆流动度的负作用影响明显减弱;蒙脱土（1.0%,以砂质量计）存在时,为获得与无蒙脱土时相同的混凝土坍落度,β-环糊精类聚羧酸减水剂的掺量增幅减小,掺加β-环糊精类聚羧酸减水剂的混凝土抗压强度下降幅度减小。结合吸附试验分析,β-环糊精类聚羧酸减水剂抑制蒙脱土负效应能力的增强应归功于其侧链中的β-环糊精基团,β-环糊精基团具有中空筒状的刚性结构,其显著的空间位阻效应将阻止蒙脱土颗粒继续吸附其他β-环糊精类聚羧酸分子,进而提高聚羧酸减水剂抑制蒙脱土负效应的能力。     

Effect of chain transfer agents in polycarboxylate superplasticizer on slump-retention of concrete

Two types of slump-retention polycarboxylate superplasticizers (PC-M and PC-S) were synthesized by using 3-mercaptopropionic acid or sodium hypophosphite as chain transfer agents, the effects of polycarboxylate superplasticizers on slump-retention of cement and concrete were investigated, and the mechanism of action and the structure of polycarboxylate superplasticizers were investigated by using conductivity, complexing Ca²⁺ concentration, gel permeation chromatography (GPC), nuclear magnetic resonance hydrogen spectroscopy (¹H-NMR), and nuclear magnetic resonance phosphorus spectroscopy (³¹P-NMR). The results indicated that the slump flow of cement paste mixed with PC-M was increased quickly within 60 min and then lost gradually, while PC-S increased slowly and evenly within 240 min. The slump flow of concrete mixed with PC-S reached 405 mm after 150 min, but the concrete mixed with PC-M was almost no fluidity after 150 min. The conductivity of the PC-M aqueous solution decreased quickly within 45 min, then slowly decreased, while the conductivity of the PC-S aqueous solution decreased slowly within 180 min. PC-M had a much greater complexation ability of Ca²⁺ than PC-S. The composition and structure of the two slump-retention polycarboxylate superplasticizers were altered by different chain transfer agents, and the hydrolysis-adsorption capacity of each component was different. The rate of hydrolyzation-adsorption of each component was PC-M₃ ≈ PC-S₃>PC-M₁>PC-M₂ ≈ PC-S₁>PC-S₂. The faster the adsorption rate, the faster the slump flow loss of concrete.     

Synthesis and performance of a modified polycarboxylate dispersant for concrete possessing enhanced cement compatibility

It is well established that the performance of polycarboxylate (PCE) superplasticizers can be severely affected by the composition of individual cements. Here, a novel allylether/maleic anhydride (APEG)‐based PCE was synthesized using allyl maleate monomer as a new, additional building block. When polymerized into the PCE main chain, this building block was found to form a cyclic lactone structure. The resulting PCE molecule was tested with respect to the dispersing force in cements possessing different phase compositions and alkali sulfate (K₂SO₄) contents. These data were compared with those from conventional APEG‐ and methacrylate ester (MPEG)‐type PCEs. Results obtained from cement paste flowability and adsorption measurements suggest that the modified PCE disperses all cement samples well and hence is more robust against variations in cement composition. Apparently, the new building block induces a higher affinity of the polymer to the surface of cement and can form a denser polymer layer. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

榆林煤制水煤浆添加剂的筛选及成浆性研究

介绍了几种添加剂对榆林煤成浆性能的影响。实验发现,当萘系A与木质素A比例为40∶60时,对金牛沟煤较适合的水煤浆浓度为64%,添加剂加入量为0.5%。对上河沟煤较适合的水煤浆浓度为63%,添加剂用量0.6%。     

Optical rotatory dispersion and circular dichroism studies of copolyaspartates with long alkyl side chain

Copoly(hexyl-l-aspartate-benzyl-l-aspartate), copoly(nonyl-l-aspartate-benzyl-l-aspartate) and copoly(dodecyl-l-aspartate-benzyl-l-aspartate) with various compositions were prepared by ester exchange reaction of poly(β-benzyl-l-aspartate). Copolyaspartates of low degree of alkylation were found to take a left handed α helix, similar to poly(β-benzyl-l-aspartate), and those of high degree of alkylation changed to a right handed α helix. Copoly(hexyl-l-aspartate-benzyl-l-aspartate) and copoly(dodecyl-l-aspartate-benzyl-l-aspartate) changed helix sense from left to right at 50% hexylation and 10% dodecylation, respectively. A small induced circular dichroism trough appeared around 230nm for these two copolyaspartates above 75% alkylation, indicative of a certain ordering of the carbonyl group due to the formation of an ordered structure of a long alkyl side chain. However, copoly(nonyl-l-aspartate-benzyl-l-aspartate) of 13% nonylation exhibited the induced circular dichroism spectrum and took a left handed α helix. Copoly(nonyl-l-aspartate-benzyl-l-aspartate) caused the reversal in helix sense above 70% nonylation according to a stabilizing effect of the ordered structure of the side chain.     

Effect of pH on the properties of barium titanate slurries with an aniomic dispersant

The colloidal stability of barium titanate (BT) aqueous suspensions with poly(acrylamide/4‐carboxylamino‐4‐oxo‐2‐butenate) (PAAM/COB) at pH 7, 9, and 12 has been investigated by means of ζ potential, adsorption, sedimentation, and particle size measurements. The isoelectric point of BT powder is at pH 4.6 and the value of ζ potential decreases as the pH of suspensions increases. The adsorption of PAAM/COB onto BT particles follows the Langmuir adsorption isotherm. The saturated amount of adsorbed polymer decreases with increasing pH. In general, BT particles in basic solutions with PAAM/COB are more stabilized, and less agglomerated than those without any dispersant present. As pH is increased, the resulting ζ potential becomes more negative, although lower polymer concentration is required for monolayer coverage of particle surface. Consequently, the resulting suspensions become more stabilized, and contain powder with smaller particle size. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1082–1088, 2006     

温度和固相粒径与浓度对水煤浆管内流动壁面滑移的影响

通过改变管径、温度、煤粉粒度和浓度,在中试规模的输送装置上研究水煤浆直管内的滑移流动规律,联合采用Mooney滑移修正方法和Tikhonov正则化方法确定浆体壁面滑移特性。结果表明,随温度和固相粒径的增大,临界剪切应力降低,壁面滑移速度显著增加;浓度越高,临界剪切应力及产生相同滑移速度所需的壁面剪切应力越大,温度升高对临界剪切应力和屈服应力的降低越显著;低壁面剪切应力下的滑移贡献率主要取决于临界剪切应力及屈服应力的相对大小,高壁面应力下主要取决于壁面滑移速度和浆体真实流变特性。