亚微米ZnO粉体在水中分散特性的研究

以聚丙烯酰胺和聚乙二醇20000为分散剂，通过沉降正交实验对ZnO颗粒的分散稳定性和分散剂、溶液pH值、球磨速度以及球磨时间对ZnO分散行为的影响进行了研究。结果表明：不同分散剂的分散效果不同，分散剂用量及溶液pH值对颗粒的分散有着显著的影响，并获得了制备20％ZnO水悬浮液的最优化配方。最后对亚微米ZnO水分散体系的形貌进行了观察和分析。     

Morphology evolution of immiscible LDPE/PVC blends in the presence of compatibilizer and phase dispersant

Phase dispersion and coalescence in low‐density polyethylene (LDPE)/polyvinyl chloride (PVC) (70/30) blends influenced by compatibilizer and phase dispersant was studied. It was found that the morphology evolution of blends is sensitive to not only processing conditions (shear strength and mixing time) but also the added compatibilizer or phase dispersant. In our conditions, the stable phase morphology of each blend is obtained after mixing 15–25 min. In addition, the dispersed PVC phase in blends is easy to aggregate when the mixing rotor speed changed from high to low for the binary blends. As a compatibilizer, chlorided polyethylene (CPE) or nitrile rubber (NBR) can stabilize the morphology and hinder the coalescence of the dispersed PVC phase when added to the blends. However, the phase dispersant butadiene rubber (BR) or styrene butadiene rubber (SBR) could not stabilize the phase structure, although it could accelerate phase dispersion. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 763–772, 2004     

气液固三相体系搅拌混合研究进展

综述了桨型、挡板及气体分布器等结构因素；转速、气量及颗粒分率等操作因素；颗粒直径及密度等物性因素对气液固三相体系的临界搅拌转速、功耗、气含率的影响。     

Slump loss and compressive strength of concrete made with WRR and HRWR admixtures and subjected to prolonged mixing

The effect of four water-reducing and retarding admixtures, and three superplasticizers on the consistency (slump) of fresh concrete, was studied at 21°C and 32°C in concrete mixes, made of OPC containing 10% fly ash, and subjected to prolonged mixing for up to 180 min. The effect of such mixing on compressive strength of concrete, at the ages of 3, 7, 28 and 90 days, was also studied. It was found that the admixtures in question accelerated the rate of slump loss at all ages, concrete compressive strength linearly increased with mixing time. The rate of slump loss, and the water demand of the concrete mixes increased within the temperature range studied.     

净浆流动度损失与混凝土坍损的相关性研究

对粉煤灰取代水泥量、粉煤灰质量,砂的含泥量和外加剂掺量等因素对净浆流动度经时变化及混凝土坍落度损失的影响进行了研究,探索了净浆保持性与混凝土坍损间的关系。结果表明:砂的含泥量对混凝土的工作性能影响明显,当实验所用砂含泥量达到I、II类时,同掺量外加剂的净浆流动度保持性能可以较为准确地反映出混凝土的工作性能;当实验所用砂为III类时,净浆流动度保持性能优异的外加剂掺量增加10%推荐为混凝土的试拌试验掺量。     

Colloidal Consolidation of Ceramic Nanoparticles by Pressure Filtration

The applied pressure and suspension height during consolidation of an aqueous suspension of nanometer-sized particles (24 nm hydroxyapatite, 30 nm SiC, 68 nm 8 mol% yttria-stabilized zirconia, 150 nm Al₂O₃, and 800 nm SiC) were continuously recorded using a pressure filtration apparatus. The packing density decreased when the particle size was less than 70 nm. The final packing density of 150−800 nm particles at 19 MPa was strongly influenced by the surface charge. However, surface charge does not affect the packing density of particles less than 70 nm. The ratio of the energy applied to two particles during consolidation to the interaction energy between two particles in a suspension was correlated to the packing density. The low packing density of 20−30 nm particles was improved by steric stabilization. The estimated thickness of the dispersant layer adsorbed on the particle surfaces was less than 1 nm and nearly independent of the molecular weight of the dispersants. When the applied pressure was released, the height of the consolidated cake increased because of the release of the elastic strain stored in the dispersant layer.     

分散剂对ZrO2料浆及陶瓷性能的影响

分散剂是流延料浆中的关键组元.本文选用了3种分散剂(三乙醇胺、磷酸三丁酯、松油醇),通过对分散剂用量、pH值对ZrO2料浆性能的影响、素坯及烧结体密度、气孔率和收缩率等方面的研究,分析比较了分散剂对料浆及陶瓷性能的作用.实验结果表明:pH在10～12.5内,三乙醇胺对ZrO2粉体的分散用量少、料浆稳定,适于制备气孔少,致密度高的ZrO2固体电解质薄片.     

Competitive adsorption between superplasticizer and retarder molecules on mineral binder surface

In a self-levelling mortar based on the ternary binder system ordinary Portland cement (OPC), calcium aluminate cement (CAC) and anhydrite, a polycarboxylate-based superplasticizer (PC) showed no plasticizing effect in combination with citrate retarder while good flowability was observed with tartrate. The mechanism behind the incompatibility between PC and citrate was investigated by means of adsorption and zeta potential measurements. Also, anionic charge densities of the admixtures were compared. Adsorption measurements revealed that, in presence of citrate, PC adsorption drops dramatically to less than 10% of dosage added, implying a complete loss of fluidity in the paste. In presence of tartrate, however, PC adsorption remains high enough to still provide good flowability. In contrast, adsorption of casein biopolymer is not much affected by addition and type of retarder. Thus it provides high fluidity with both retarders. Comparison of specific anionic charge density of Ca²⁺ retarder complexes and PC reveals a direct correlation between their adsorption behaviour and anionic charge density. Admixtures with higher anionic charge density show higher affinity to the binder surface and thus adsorb preferredly. When several admixtures are present, molecules with lower anionic charge density will adsorb only if, after adsorption of the admixture with higher anionic charge, a cationic surface charge and enough adsorption area still exists. The incompatibility problem between PC and citrate in the self-levelling mortar formulation was solved by increasing the anionic charge density of the PC molecule. Similar to casein, adsorption of this modified PC is not much influenced by retarder molecules.     

聚羧酸减水剂(醚型)的合成工艺及生产应用

研究了聚合反应工艺,确定了聚羧酸系减水剂的反应条件和工艺参数.应用制备的聚羧酸减水剂按混凝土相关标准对其性能进行了测试,结果表明所制备的减水剂具有掺量小、减水率较高以及坍落度保持性好的特点,对混凝土的性能有显著改善.     

Effects of retempering on consistency and compressive strength of concrete subjected to prolonged mixing

In this study, effects of prolonged mixing and four different retempering processes on some properties of fresh and hardened concrete, such as temperature, slump loss, and strength, were investigated. Two types of concrete mixtures with different compression strength having 15 cm initial slump were produced in a laboratory mixer. After mixing for 5 min at 20 rpm speed to ensure homogeneity, the mixing was continued at 4 rpm for a period of up to 4 h to simulate the prolonged agitation of ready-mixed concrete in truck mixers. Concrete samples were taken out of the mixer at the end of first, second, third, and fourth hour for estimating the effects of prolonged mixing on properties of fresh concrete. For restoring the initial workability, four different retempering methods were used and their effects on properties of concrete were investigated. Results show that compared to the untempered concrete mixtures, those tempered with solutions prepared by 3% or 4.5% solid superplasticizer by mass of retempering water had significantly less loss of 28-day compressive strength.     

PDMS/SiC功能梯度复合材料3D打印主动混合喷头结构设计与工艺参数优化

以高黏度材料聚二甲基硅氧烷（PDMS）和碳化硅（SiC）粉末混合液为例，利用流体动力学仿真模拟，设计并优化主动混合喷头。仿真分析不同螺杆结构对主动混合喷头混合效果的影响，选定双向四螺旋螺杆结构，同时探究了螺杆长度、螺杆与腔体间隙等结构参数对混合效果的影响规律，确定螺杆长度为12 mm、螺杆与腔体间隙为0.2 mm；优化了该结构的转速、入口速度等工艺参数，确定转速为60 r/min、入口速度为1 mm/s。此外分析了该结构在不同材料体积配比下均可进行有效混合。最后，通过打印试样，验证了该主动混合喷头能够实现复合材料的有效混合。     

DMC催化制备烯丙醇聚氧乙烯醚及其应用性能研究

用ZnCl_2和K_3Co(CN)_6制备双金属氰化络合物催化剂(DMC),继而用该催化剂进行乙氧基化反应,合成了烯丙醇聚氧乙烯醚APEG(5000)-A。通过凝胶色谱以及双键保留率的检测,杂质聚乙二醇含量为1.78%,比传统APEG(5000)-B低,双键保留率比传统APEG(5000)-B高。对以A:PEG(5000)-A为大单体合成的减水剂与传统APEG(5000)-B大单体共聚而成的减水剂进行混凝土的坍落度及坍落度保持性对比试验,结果表明使用该APEG(5000)-A合成的聚羧酸减水剂的性能更佳。     

Fabrication of Tiron‐doped polypyrrole/MWCNT composite electrodes with high mass loading and enhanced performance for supercapacitors

In this study, the aromatic sulfonate compound Tiron with high charge to mass ratio is used as an anionic dopant for synthesis of polypyrrole (PPy). The fabricated PPy is investigated for electrochemical supercapacitor (ES) application. Testing results show that Tiron allows reduced PPy agglomeration, smaller particle size and improved charge storage properties of PPy. High capacitance and improved capacitive retention at high scan rates are achieved by the fabrication of PPy/multiwalled carbon nanotube (MWCNT) composite electrode using safranin (SAF) as a co‐dispersant. The Tiron‐doped PPy electrode shows the highest capacitance of 7.8 F cm^?2 with a mass of 27 mg cm^?2. The Tiron‐doped PPy/MWCNT composite electrode shows good capacitance retention with a capacitance of 1.0 F cm^?2 at the scan rate of 100 mV s^?1. Symmetric supercapacitor cells are fabricated using PPy based active materials. An energy density of 0.36 mWh cm^?2 is achieved. The energy/power density and capacitance retention of the Tiron‐doped PPy/MWCNT ES is significantly improved in comparison with PPy‐based ES, prepared without Tiron or MWCNT. The Tiron‐doped PPy/MWCNT symmetric supercapacitor presents good cycling performance with 91.4% capacitance retention after 1000 charge–discharge cycles. The PPy/MWCNT composites, prepared using Tiron and SAF co‐dispersant, are promising electrodes for ES. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42376.     

酯型聚羧酸高性能减水剂的生产工艺及应用

研究了酯化反应工艺、聚合反应工艺等，确定了聚羧酸减水剂的反应条件和工艺参数。应用制备的聚羧酸减水剂按混凝土相关标准对其性能进行了瘌试，结果表明所生产的减水剂具有掺量小、减水率较高以及坍落度保持性好的特点，对混凝土的性能有显著改善。     

pH值缓冲剂的使用探讨

介绍了氯乙烯聚合反应体系pH值的变化对分散剂的稳定性和引发剂的分解速率的影响。pH值较高时,影响分散效果及颗粒形态,容易生成大颗粒;pH值较低时,影响分散剂的稳定性,聚合速率降低。一般情况下,聚合反应pH值控制在6~9。济宁中银电化有限公司采取加入合适的pH值缓冲剂的方法来稳定聚合反应体系的酸碱度,并比较了几种pH值缓冲剂对PVC树脂质量的影响,认为碳酸氢铵是理想的pH值缓冲剂。     

Effect of retempering with superplasticizer admixtures on slump loss and compressive strength of concrete subjected to prolonged mixing

To have concrete possesses the specified engineering properties, its slump loss has to be compensated somehow at construction site so that concrete could be placed and compacted properly. Several attempts have been tried so far to render concrete workable at construction site including starting with a high initial slump at the stationary plant, or retempering with water and/or with chemical admixtures at construction site. In this investigation, ASTM C 494 Type F superplasticizer was used for retempering concrete to restore its initial slump. Concrete mixes having an initial slump of about 19 cm were prepared and subjected to prolonged mixing with different mixing duration such as 30, 60, 90, 120, and 150 min following an initial mixing of 5 min to ensure homogeneity. At the end of each mixing period, cube specimens of 15 cm were cast from concrete retempered to its initial slump level and tested at the age of 28 days for compressive strength. Results revealed that compared to the concrete retempered with water, those retempered with a superplasticizer admixture have yielded significantly higher strength regardless of the mixing duration.     

单孔射流流化床内颗粒混合特性的数值模拟

在欧拉-拉格朗日坐标系下,采用离散单元法对单孔射流流化床内颗粒混合特性进行了数值模拟。引入混合指数对床内轴向及径向布置的颗粒混合质量进行定量分析,并研究了不同表观气速、不同弹性系数对颗粒混合特性的影响。模拟得到了颗粒轴向及径向混合序列图、气体和颗粒速度分布、整床颗粒混合指数分布、参量变化时整床颗粒混合指数分布。结果表明：流化床床层内颗粒混合速度受颗粒内循环能力和颗粒扩散能力的综合作用。单口射流喷动流化床颗粒轴向混合速度主要由颗粒内循环速度决定,颗粒径向混合速度主要由颗粒扩散能力决定。表观气速增大时,颗粒内循环速度增加,从而加快了颗粒轴向混合进程,但对颗粒径向混合影响微弱;弹性系数增大时,颗粒混合速度及混合质量均下降,并且弹性系数增大对颗粒径向混合进程影响小于颗粒轴向混合。     

机制砂石粉对聚羧酸减水剂性能影响

研究了机制砂石粉的岩性、含量、细度对减水剂饱和产量、保坍性能和引气性能的影响。试验结果表明,玄武岩的饱和点掺量最高,砂浆流动度损失较大,保气性能较差,对胶砂和混凝土工作性能影响最大;机制砂中石粉含量的增加,减水剂的饱和点增大,减水剂敏感性增强,保坍性能下降,石粉含量过低或者过高都会影响减水剂的引气性能;随着石粉细度增加,减水剂饱和掺量先减小后增大,引气性能先增加后降低,保气性能逐渐变好,在细度小于等于700目时,减水剂保坍性能变化较小,细度继续增加,保坍性能下降。     

Modification of the molar anionic charge density of acetone–formaldehyde–sulfite dispersant to improve adsorption behavior and effectiveness in the presence of CaAMPS®‐co‐NNDMA cement fluid loss polymer

Sulfonated aldol polycondensates were synthesized from acetone, formaldehyde, and different amounts of sodium sulfite, resulting in polymers with varying degrees of sulfonation (DS). The anionic charge amount of these macromolecules measured by polyelectrolyte titration decreased with lower DS. The effectiveness of the acetone–formaldehyde–sulfite (AFS) polycondensates as cement dispersant was found to depend on the amount of polymer adsorbed on cement. AFS adsorption decreases with lower DS. Interaction and compatibility between AFS and CaAMPS®‐co‐NNDMA fluid loss additive was studied by formulating binary additive systems composed of one of the modified AFS polymers and CaAMPS‐co‐NNDMA. At high DS, AFS adsorbs strongly and prevents CaAMPS‐co‐NNDMA from adsorbing in sufficient amounts on the cement surface. The result is poor fluid loss control of the cement slurry. AFS polymers with lower DS, however, allow simultaneous adsorption of both polymers in sufficient quantities to provide good fluid loss control and low rheology at the same time. Thus, effectiveness of both additives was retained. Obviously, effectiveness of such multi‐admixture systems depends on the adjustment of the adsorption behavior of the individual components relative to each other. Molar anionic charge density of the polymers was found to be a major parameter influencing their relative adsorption behavior. The AFS polymer with DS = 0.2 possesses a molar anionic charge density comparable to CaAMPS‐co‐NNDMA. Thus, when admixtures with similar molar anionic charge densities are used, the performance of one component is not negatively influenced by the other. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

新拌水泥浆体结构及其触变特性的探讨

本文采用“台阶”法测试触变性,研究了新拌水泥浆体结构与触变特性的关系,提出了定量表征浆体结构状态的新的触变参数A_i和A,探讨了“台阶”法触变性研究对实际工程的指导意义。