Influence of Polycarboxylate Dispersants with Different Molecular Structures on the Performance of Coal Water Slurry

Polycarboxylate dispersants have variable structures and can be designed according to practical needs. Further study on the influence of molecular structures on the performance of coal-water slurry (CWS) has vital significance. A variety of polycarboxylate dispersants was designed and synthesized with different monomers. The performance of each dispersant for the low-rank China CWS (i.e., Shenfu coal) was evaluated. Results showed that sodium p-styrene sulfonate (SSS) was the most efficient monomer with better adsorption performance on the surface of coal particles and lower apparent viscosity (i.e., mole ratio of SSS and acrylic acid (AA) sodium 65:35, CWS concentration 63 wt%, dispersant dosage 0.5 wt%). Polyethylene glycol acrylate (PA) was also effective. In addition, 5 wt% cationic monomer methyl acryloyl oxygen ethyl trimethyl ammonium chloride (DMC) was introduced into the structure. The polycarboxylate dispersant with optimal molecular structure was applied in Shenfu coal. The performance of water slurry could meet the national standards well (i.e., apparent viscosity 920 mPa · s), displaying good rheological property and stability.     

Dispersion of Zirconia in the Presence of Dolapix PC75

The effect of Dolapix PC75 on the electrokinetic and rheological behavior of nano zirconia particles is presented here. The effect of pH, concentration of dispersant, and solids loading on zeta-potential and rheological behavior was studied. Upon interaction with the dispersant, the iso-electric point of zirconia changed and the surface became more negative with increasing concentration of dispersant, suggesting a strong interaction. Maximum charge was obtained in the presence of about 200 ppm of Dolapix. Rheological tests at pH 7 showed that the zirconia suspension is viscous at high solids loading and addition of the dispersant decreased the viscosity substantially especially at high solids loading (>50 wt%). Sedimentation tests confirmed that Dolapix PC75 is a good dispersant for zirconia particles at pH values of 7 and above.     

粘度和光谱方法研究二元阴离子型丙烯酰胺共聚物(P3A)在不同pH水溶液中的构象变化

采用粘度和光谱方法,研究了强酸性和弱酸性2种阴离子型单体与丙烯酰胺的三元共聚物(P3A)在稀水溶液中pH诱发的构象变化,P3A聚合物由丙烯酰胺(AM)和强酸性离子单体(AMPS)及弱酸性离子单体(AA)组成.试验结果表明P3A聚合物溶液的粘度随pH呈现非单调的增长关系,在pH为4～5范围内产生急剧的升高,这现象归因于聚合物链团从紧密状态向膨胀状态迅速的转变.这两种状态的溶液粘度变化幅度和聚合物P3A中AMPS和AA组合比例紧密相关,芘探针在聚合物P3A溶液中的荧光强度和pH的关系呈现类似粘度变化的结果.在低pH值时,发现单一弱酸离子共聚物(P2AA)溶液发生相分离,然而在含有强酸单元(AMPS)的P3A聚合物情况下,这种现象不再产生.     

弱凝胶钻井液成胶剂AM/AMPS/OA_8的合成与表征

针对水平井、大斜度井钻井过程中井眼润滑性、岩屑携带以及钻井速度的影响等问题,通过合理的分子设计,以丙烯酰胺(AM)、2-丙烯酰胺-2-甲基丙磺酸(AMPS)和实验室自制疏水单体丙烯酸正辛醇OA_8为原料,利用胶束聚合法,制备了一种弱凝胶成胶剂AMAMPSOA_8,其结构经1H NMR和IR表征。以AMAMPSOA_8在低剪切速率下的表观粘度为指标设计正交试验,确定最优反应条件为:AM与AMPS摩尔配比为4.8∶1,引发剂用量为单体总质量的0.04%,疏水单体浓度为0.75%,于70℃反应9 h。该条件下,0.5%AMAMPS0A_8聚合物溶液在低剪切速率3 r·min~(-1)下表观粘度可达23 680 mPa·s。利用热分析仪、高温滚子炉、高温高压流变仪对产物性能进行了研究。研究表明:AMAMPSOA_8的抗温性能可达160℃;聚合物溶液体系有明显的触变性,在40 min后溶液切力增加幅度变缓。     

Sulfobutylated Lignosulfonate with Ultrahigh Sulfonation Degree and Its Dispersion Property in Low-Rank Coal-Water Slurry

Using a simple method, we developed a new family of alkyl sulfonic acid modified lignosulfonate (ASLSs) with simultaneously improved sulfonation degrees and molecular weights via one step. Direct sulfonation occurred on both phenolic and alcoholic hydroxyl groups of alkali lignin raw material with 1,4-butylenesulfone used as sulfonation agent. A sulfonation degree of 3.86 mmol/g had been achieved which presents as one of the highest sulfonation degrees among those of reported LSs, to date. ¹H-NMR and Fourier transform infrared spectroscopy measurements confirmed the efficient sulfonation. Furthermore, the dispersion properties were investigated in low-rank coal-water slurry (CWS). ASLS3 showed better viscosity-reduction effect than naphthalene sulfonate formaldehyde condensate (FDN) in CWS with dosages from 0.6% to 1.0 wt%. ASLS3 had the similar sulfonation degree with FDN; however, the large steric hindrance, soft long alkyl chain-C₄H₈-SO₃H, and their efficient anchoring effect of ASLSs contributed to their improved dispersion properties.     

Effect of sodium dodecyl benzene sulfonate to the displacement performance of hyperbranched polymer

Experimental studies were conducted to realize displacement performance effect of anionic surfactant sodium dodecyl benzene sulfonate (SDBS) on hyperbranched poly(AM/AA/AMPS/GA), which was successfully synthesized via free radical polymerization using modified dendritic functional monomer (GA), acrylamide (AM), acrylate (AA), and 2-acrylamido-2-methyl propane sulfonic acid (AMPS). Compared with individual polymer, SP (surfactant polymer) binary systems showed lower apparent viscosity, interfacial tension, and hydrodynamic radius as the result of the electrostatic repulsion between the tail end of hydrophilic polymer branched chain and the head of the surfactant. It was found from abundant static adsorption and dynamic retention tests that the values of static adsorption and dynamics retention of SDBS which is mixed with hyperbranched polymer decrease due to the competitive interaction. However, unlike this phenomenon, SDBS would heighten the dynamic retention value of poly(AM/AA/AMPS/GA), resulting in addition of residual resistance factor. Oil displacement experiment indicated that SP solutions have greater capability of enhance oil recovery than individual polymer under same conditions.     

Preparation and Rheological Characterization of Polymer Nanocomposites Based on Expanded Graphite

A new type of conductive filler, namely expanded graphite (EG), was used to prepare novel nanocomposites. The EG was incorporated into several rather different polymers, specifically polycarbonate (PC), low‐density polyethylene (LDPE), isotactic polypropylene (PP), and polystyrene (PS), using melt mixing in a small‐scale DACA‐Microcompounder. The EG content was varied between 1 and 20 wt%. The rheological properties and morphologies of the nanocomposites were characterized by melt rheology and scanning electron microscopy (SEM), respectively. The melt‐state linear viscoelastic properties were investigated using an ARES rheometer, with the measurements performed in the dynamic mode at various temperatures over a wide range of frequencies. Addition of the EG increased the linear dynamic moduli and melt viscosity of the materials. Up to a certain critical concentration of EG, the materials exhibited a simple liquid‐like behavior. Above this concentration, however, significant changes in the frequency dependences of the moduli and viscosity were observed. In addition, the moduli showed a liquid‐solid transition resulting in a second plateau in the low frequency‐regime, and the complex viscosity revealed shear‐thinning behavior. Specific values of this percolation concentration were found to be at around 4 wt% in the case of PC/EG, 9 wt% for PP/EG and PS/EG, and 12 wt% for PE/EG. This critical concentration was correlated to a network‐like structure formed through interactions between the EG platelets and the polymers. The extent of these complications was found to vary from polymer to polymer, presumably due to different degrees of EG exfoliation and dispersion arising from different EG‐polymer interactions and from variable shearing forces dependent on the polymer viscosities. The formation of network‐like structures is very sensitively displayed using van Gurp‐Palmen plots, which are most suitable for identifying “rheological percolation” in our investigated systems.     

Synthesis and properties of temperature-resistant and salt-tolerant tetra-acrylamide copolymer

Abstract

The acrylamide copolymer with acrylamide as its main monomer is a modified polyacrylamide. In addition, the acrylamide copolymer is generally to dissolve or swell in water and can be used as thickener, dispersant, flocculant and so on. Therefore, using Acrylamide AM, 2-acrylamide-2-methyl propanesulfonic acid AMPS, dimethyldodecyl (2-acrylamidoethyl) ammoniumbromide AQ₁₂ and vinyltriethoxysilane VTEO as raw materials so that a series of four-membered acrylamide copolymers are prepared in aqueous solution polymerization. The amphoteric structure in the polymer has a unique anti-polyelectrolyte behavior when it is electrically neutral, which can significantly improve the salt resistance of the aqueous polymer. In addition, the hydrolysis of the vinyltriethoxysilane containing silicon structure by hydrophobic association can improve the temperature resistance of the polymer. The optimal reaction conditions were determined by orthogonal experiment: the reaction temperature was 10?°C; the initiator concentration was 0.05?mol%; the monomer concentration was 25?wt% and the pH was 7. Properties of polymer solution indicated that the series of tetra-copolymer possessed salt-tolerant and heat-resisting performances. As an oil displacing agent, it can significantly improve the efficiency of oil displacement, and particularly highlights the effect of 4-member copolymer as an oil displacing agent.     

Polymeric Fluorosurfactant‐Mediated Perfluorocarbon Emulsions

Polymeric fluorosurfactants, using poly(N,N‐dimethylacrylamide) (PDMA) or PDMA copolymers containing acrylic acid (AA) or 2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid (AMPS) comonomers were synthesized by copolymerization of DMA, DMA/AA, or DMA/AMPS and methacrylates composed of 1,1‐dihydroperfluorodecanoyl groups separated from the methacrylate by polyethylene glycol (PEG) groups with molecular weights ranging from 1 to 6 kD. The stability of aqueous perfluorocarbon (PFC) emulsions mediated by these polymeric fluorosurfactants was found to be affected by polymer concentration, ionic comonomer content, perfluoroalkyl (R_F) comonomer content, and PEG spacer length. Thus, emulsion stability characterized by average particle size and morphology was improved by increased AA or AMPS content (up to 30 weight percent), increased PEG chain length and R_F comonomer content, and greater polymer concentration.     

水煤浆添加剂与煤之间的相互作用规律研究 Ⅰ. 复合煤颗粒间的相互作用对水煤浆流变性的影响

使用12种不同分散剂对14种不同变质程度的煤进行了成浆性实验，分析了182个水煤浆(CWS)样品的流变性。结果表明，低变质程度和高灰煤浆多呈屈服假塑性，煤的性质起主导作用；变质程度高且灰分较低煤浆的流变性，主要依赖于分散剂的结构与性质；分子结构单元立体空间效应大，疏水基团与亲水基团呈立体间隔分布的分散剂，易形成屈服假塑性CWS；分子线度长，亲水基团与疏水基团呈线性间隔分布的分散剂，易形成胀塑性CWS。复合煤粒间的相互作用方式是决定CWS流变特性的关键。     

新疆褐煤疏水改性提高其成浆性能

针对新疆褐煤具有较高内水的问题,制备了阴离子AKD改性剂和非离子AKD改性剂,对褐煤颗粒进行疏水改性。研究了改性前后煤粒表面化学成分、孔隙分布、亲疏水性和Zeta电位等煤粒表面特性,并结合NSF分散剂在改性前后煤粒表面吸附量大小,探讨了改性前后褐煤水煤浆的成浆性、流变性和稳定性。结果表明,改性后煤粒孔隙结构降低,煤粒表面碳的相对含量增加,氧的相对含量降低,煤水界面接触角增加,煤粒疏水性能增强。NSF分散剂在改性煤表面吸附量增加,煤粒表面负电性增强。由阴离子AKD改性煤、非离子AKD改性煤制备的水煤浆最大成浆质量分数从原煤56.6%分别增加至61.0%、62.5%,浆体析水率从原煤13.97%分别降低至7.45%、7.89%,同时改性后煤粒制备的浆体均表现出剪切变稀的假塑性流体。因此,改性煤粒更容易制备高浓度、低黏度、高稳定性且易于储存和运输的水煤浆。     

Stability enhancement of nanofibrillated cellulose in electrolytes through grafting of 2-acrylamido-2-methylpropane sulfonic acid

This study aimed to improve the stability of nanofibrillated cellulose (NFC) in an electrolyte containing system, which was achieved by the grafting of 2-acrylamido-2-methylpropane sulfonic acid (AMPS) via the ceric ammonium nitrate-induced polymerization process. The results indicated that upon grafting the salt resistance and thermal stability of NFC were significantly improved. Moreover, the stability of the modified NFC increased with the AMPS loading. Compared to the control (the original NFC), the poly-AMPS/NFC (357.5 mg/g AMPS) exhibited much improved stability in a 400 mmol/L NaCl solution, and its viscosity was 350 mPa s. The thermogravimetric analysis results showed that the initial decomposition temperature of the modified NFC increased from 265 to 330 °C. Transmission electron microscopy (TEM) observations showed that the main morphologic features of NFC were not altered, suggesting that the grafting reaction occurred on the fiber surface. The modified NFC can have promising industrial applications, such as oil recovery.     

聚羧酸系高效减水剂合成工艺的优化研究

以甲基烯丙基聚氧乙烯醚(HPEG)和丙烯酸(AA)为单体,以过氧化氢-抗坏血酸(H2 O2-Vc)为氧化还原引发体系,以巯基丙酸(MPA)为链转移剂,共聚合成了HPEGAA型聚羧酸减水剂.研究了合成温度、酸醚比及引发剂用量对聚羧酸减水剂分散性能的影响.结果表明,聚羧酸减水剂的最佳合成工艺为:n(AA):n(HPEG)=...     

Investigations of the dissociation behavior and interfacial adsorption characteristics of polyelectrolytes from poly(acrylamido‐2‐methyl‐1‐propane sulfonic acid) with an octadecyl side chain

Water‐soluble polymeric amphiphiles derived from acrylamido‐2‐methyl‐1‐propane sulfonic acid (AMPS) and octadecyl monomers in which the linker groups vary among acryloyl [octadecyl methacrylate (ODMAc)], maleate [octadecyl maleate ester (ODME)], and maleamic acid [octadecyl maleamic acid (ODMA)] have been synthesized. The dissociation behavior in water from potentiometric titration suggests that these polymers show resistance to neutralization. This might arise from coil structures, which effect the destabilization of sulfonate ions because of a proximity effect. The effect of the ? COOH group in modifying the dissociation behavior in the copolymers AMPS–ODME and AMPS–ODMA is indicated. The ratio of the intensities of the third vibronic peak (I₃) to the first vibronic peak (I₁) of the fluoroprobe pyrene in the presence of polymer solutions shows negligible changes as a function of pH, and this suggests the retention of micropolarity. The high I₃/I₁ value observed in the presence of the ODMAc polymer suggests intermolecular association. The reduction in the reduced viscosity with the concentration of the polymers suggests the polyelectrolyte behavior of all the copolymers. The progressive decrease in the reduced viscosity from 120 to 95 mL/g when the degree of ionization increases from 0.5 to 1 for the ODME polymer suggests changes in the solution structure. AMPS–ODMA and AMPS–ODME polymers exhibit significant adsorption at the interface and exhibit equilibrium surface tensions of 58.8 and 56.3 mN/m, respectively. The lower surface activity and higher reduced viscosity of ODMAc polymer solutions further support the formation of intermolecular associated or network structures. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 314–324, 2006     

Viscosity behavior of polyelectrolyte copolymers containing sulfonate groups in mixed organic solvents

Copolymerization of 2-acrylamido-2-methylpropane sulfonic acid (AMPS, monomer 1) with 2-hydropropyl methacrylate (HPM, monomer 2) was conducted in ethylene glycol/water (1 : 1 in weight) at 70°C. The reactivity ratios estimated from the copolymer composition at low conversion are r₁ = 2.31 ± 0.25 and r₂ = 11.70 ± 1.05. The azeotropic composition was found at the monomer mole ratio AMPS/HPM equal to 8/2. Viscosity of these copolymers was measured in dimethyl sulfoxide (DMSO) and DMSO/tetrahydrofuran (THF) mixed solvent at 25 ± 0.05°C. Polyelectrolyte behavior was observed for all the copolymers, even in the mixed solvent containing 65 wt % of THF. The reduced viscosity at constant polymer concentration decreased with increasing THF content in the mixed solvent. The copolymers having AMPS repeat units more than 42 mol % precipitated in the mixed solvent when the THF was beyond 68 wt %. The viscosity reduction and precipitation in the copolymer solutions with increasing THF can be attributed to the dipole–dipole attraction between ion-pairs formed in less-polar medium. This is helpful in understanding the volume phase transition in highly charged hydrogels caused by mixing solvents. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35 : 1433–1438, 1997     

二元阴离子型丙烯酰胺共聚物在二价金属离子存在下相分离行为的研究

水溶性丙烯酰胺类共聚物 ,作为粘度改性剂 ,在工业上已得到广泛应用 .特别近年来 ,它们大量应用于石油工业强化采油技术 ,引起了人们很大的重视[1] .目前 ,这类用途的聚合物 ,主要在聚丙烯酰胺结构中 ,引入阴离子组分和不断增高产物分子量的方法 ,以提高聚合物溶液粘度和增粘效果 ,然而 ,在二价金属离子 (如Ｃａ2 + ,Ｍｇ2 + 等 )存在下 ,羧酸阴离子型丙烯酰胺类共聚物很容易络合发生沉淀 ,从而失去增粘作用[2 ] .同时这类聚合物中酰胺基不稳定 ,易发生水解反应转化为羧酸基 ,并随温度升高而加剧[3 ] ,因此在温度较高的应用条件下 ,二价金属…     

Rheological Behavior Investigation of Concentrated Coal-Water Suspension

The Haake rheometer is used to determine the rheological property of coal-water suspension (CWS) made up from Datong coal, and the obtained rheological curves are fitted using power-law, Binghamplastic, Herschel-Bulkley, Casson, and Sisko models, respectively. The fitted parameters indicate that the Herschel-Bulkley model has the maximum correlation coefficient of all the rheological models, so the Herschel-Bulkley model is selected to study the rheological property of the prepared CWS. By means of the Herschel-Bulkley model, the effects of coal concentration, dispersant dosage and electrolyte addition on rheological property of CWS are studied. The results show that CWS with higher coal concentration tend to be pseudoplastic behavior, and CWS prepared using excessive dispersant show shear-thickening flow characteristic. The addition of high-valence cationic electrolyte increase the yield value and the pseudoplastic behavior of CWS, while the addition of anionic adjusting agent decrease the yield value of CWS, and the CWS tend to be shear-thickening flow characteristic.     

Adsorption Properties of Uranium (VI) Ions on Reactive Crosslinked Acrylamidoxime and Acrylic Acid Copolymer Resins

Crosslinked acrylic acid (AA) acrylonitrile (AN) copolymer was prepared by suspension copolymerization in the presence of poly (vinyl alcohol) as suspending agent and N,N-methylenebisacrylamide (MBA) and divinylbenzene (DVB) as crosslinking agents. The molecular ratios between AN and AA was 95: 5 mol%. Different ratios 2, 5, and 10 wt% of crosslinkers was used. The nitrile group of the copolymer was converted to acrylamidoxime in the presence of hydroxylamine. Morphologies of the prepared resins were examined by scanning electron microscope (SEM). Recovery of uranium ions was investigated. The adsorption of uranium was occurred in nitric acid, hydrochloric acid and sulfuric acid solutions. Effect of pH, time of loading, type of acid, ratio, and type of crosslinker were investigated. Regeneration of eluted resins was determined.     

Influence of temperature and humidity on the degradation process of ascorbic acid in vitamin C chewable tablets

Ascorbic acid (AA) is the active ingredient of vitamin C chewable tablets. It is unstable even at room temperature, and increased temperature and humidity rapidly increase its degradation. To protect the active substance, we made its coating with polymers ethyl cellulose that provides its thermal protection and protection from moisture. We bet each particle of AA with a layer of polymer by the method of fluidization. Extra protection against thermal effects and penetration of moisture and oxygen provides the packaging. By using four kinds of packaging: polypropylene container for tablets, strips of aluminum and polyvinyl chloride Al/PVC strips, glass bottles, and strips of aluminum and polyethylene (Al.PE/PE.Al) of 3, of 6 months and of 12 months. One of the tablets are stored at room temperature (25 ± 2 °C/60% RH ± 5%), and the rest in terms of accelerated aging or increased temperature and humidity (30 ± 2 °C/65% RH ± 5% and 40 ± 2 °C/75% RH ± 5%). The speed of degradation of unprotected AA usually get doubled when there is increasing of the temperature for every 10 °C. Experimentally the concentration of AA was monitored, its oxidation product-dehydroascorbic acid and its degradation product-diketogulonic acid.     

不同水煤浆分散剂与煤之间的相互作用规律研究Ⅹ分散剂在煤粒表面上的吸附作用特征

研究了6种水煤浆分散剂在14种不同变质程度煤上的吸附作用特征。结果表明,多数分散剂在煤粒表面达到单层饱和吸附后,又形成多层吸附,单层饱和吸附量与煤的变质程度、比表面积以及分散剂的性质有关。在相同粒度分布下,煤的变质程度越低,表面含氧亲水官能团的比例越高,孔隙率越高,比表面积越大,这对增大吸附量有利。煤的变质程度越高,其表面疏水区面积的比例越高,分散剂通过疏水基团紧密吸附在煤表面的比例越大,这对增加高阶煤的吸附量有利。对不同煤,是变质程度还是比表面积为吸附分散剂的主控因素,主要依赖于分散剂的结构与性质。对同种煤,疏水与亲水基团呈线型分立分布的分散剂,吸附量明显高;而疏水与亲水基团呈线型间隔分布的分散剂,吸附量明显小。