基于EDEM的双卧轴搅拌机搅拌工艺 对比研究

分析了搅拌工艺对水泥混凝土性能的影响,在此基础上,研究不同搅拌工艺对双卧轴搅拌机物料搅拌均匀性的影响。利用EDEM软件对一次投料法、水泥砂浆法和水泥裹砂石法三种不同搅拌工艺对物料搅拌均匀性的影响进行了模拟仿真。仿真结果表明:二次搅拌工艺搅拌物料均匀性比传统的一次搅拌工艺优越,其中,采用水泥砂浆法物料搅拌均匀性最好,而且可降低搅拌时间。     

搅拌热在苯甲酸发热量测试中的影响研究

为研究搅拌热在苯甲酸发热量测试中的影响,通过理论推导,得出搅拌热影响量近似计算公式,并进行了实例验证。研究表明,搅拌热发热量测试结果的影响与搅拌热、主期时间、试样质量相关。当搅拌热不参与计算时,表现出试样质量小则发热量偏高,试样质量大则发热量偏低。而当搅拌热参与计算时,得出的发热量测试结果无此明显现象。因此,搅拌热作为附加热参与计算有利于提高发热量测试结果的精密度和准确度。     

搅拌对桉木浆与甲基丙烯酸缩水甘油酯接枝共聚的影响

采用铈盐和Fe2+-H2O2-二氧化硫脲两种引发体系引发甲基丙烯酸缩水甘油酯与漂白化学桉木浆接枝共聚,研究了搅拌对接枝共聚的影响。搅拌作用的强弱是由搅拌转速、反应器容积和搅拌桨大小共同决定的,三者都对接枝共聚有很大影响,三者有机组合后获得合适的搅拌强度对接枝共聚是极为重要的。除了铈盐引发接枝时环氧基水解率受搅拌转速的影响较大外,两种引发体系下搅拌对接枝的影响规律非常相似。     

制备工艺对微乳化柴油稳定性能的影响

为了考察制备工艺对微乳化柴油稳定性能的影响,采用单因素变化试验和正交试验设计安排试验,系统分析了制备微乳化柴油时的温度、搅拌速度、搅拌方式、试剂的添加顺序以及各工序搅拌时间对其稳定性能的影响。结果表明:温度为25～35℃,搅拌速度为300～500r/m in,添加顺序为乳化剂和柴油先混合,再加入水,最后加入助乳剂,各工序搅拌时间均为5m in时所制备的微乳化柴油稳定性好。结论为制备微乳化柴油时温度、搅拌速度、搅拌时间以及添加顺序对其稳定性能影响较大,搅拌方式对其稳定性能影响较小。     

振动搅拌对混凝土性能的影响

试验研究了振动搅拌对混凝土强度、含气量和工作性能的影响,结果表明:振动搅拌可以显著提高混凝土强度,但是随着养护时间增长,普通搅拌与振动搅拌混凝土试样强度差异减小;振动搅拌可以显著提高混凝土的含气量;振动搅拌对混凝土粘聚性和保水性影响不大,但是会降低混凝土的流动性。     

成型工艺对陶瓷模具石膏性能的影响

运用正交试验研究了陶瓷模具石膏主要成型工艺即体系温度、搅拌时间、浆体流态、搅拌速度四个因素对其抗折强度及吸水率的影响.结果表明:搅拌时间是影响强度的最主要因素,浆体流态、体系温度次之,搅拌速度影响最小,且前三者为显著影响因素;影响吸水率的主要及显著因素为浆体流态,其次依次为体系温度、搅拌时间,搅拌速度;确定了模具石膏最佳成型工艺条件范围为标准稠度需水量、体系温度(14±2)℃、搅拌时间2～3 min、搅拌速度(300±10) r/min,此时石膏绝干抗折强度高达6.98 MPa、吸水率约为39％.     

搅拌机有关搅拌技术的分析和探讨

本文对搅拌机的有关搅拌技术:搅拌混合特性、均一化问题、传热问题、节能问题、相似与放大问题等进行了分析,确定了评价搅拌的特性参数和影响搅拌的主要关系,提出了必须重视搅拌技术的研究,以便更好指导实际搅拌操作。     

搅拌强度对白炭黑结构的影响

研究了搅拌强度对稻壳制备优质白炭黑结构的影响，实验采用两步反应器分别探讨了搅拌浆结构和一、二步反应器搅拌浆的不同转速对白炭黑吸油值和表观密度的影响，结果表明，搅拌强度是影响白炭黑质量的主要因素之一，当采用片状搅拌浆结构时，一步、二步反应器的适宜搅拌速度分别为500r/min和250r/min。     

氟硅酸钠氨化搅拌技术研究

研究了氟硅酸钠晶体在溶液中产生氨化的搅拌技术，研究表明：搅拌强度、搅拌时间、溶液的酸度是影响氨化的主要因素。搅拌加速氨化反应，搅拌槽和搅拌器的转速，叶轮形式，规格是搅拌技术的重要参数。     

气固搅拌流化床中压力脉动特性

气固搅拌流化床反应器可用于黏结性聚合物颗粒的流态化过程,流化床中通气湍动与搅拌的相互作用关系仍不明确。通过压力脉动的统计分析、功率谱分析和小波分析,考察了搅拌桨型式和搅拌转速对流态化特性的影响规律。实验发现,搅拌转速和搅拌桨型式对床层压力影响较小,但对压力脉动影响显著。搅拌流化床中搅拌与通气湍动对流态化共同作用,双层锚式桨、框式桨等小桨叶面积的搅拌桨在较高转速条件下能强化流态化过程,与普通流化床相比具有更小的气泡尺寸和压力脉动,搅拌可抑制气泡聚并、破碎气泡,维持床层均匀流态化;而新型具有大桨叶面积的自清洁桨的搅拌作用强烈,在较高的转速下易形成桨叶前方的颗粒堆积和桨叶后方的气体短路等非正常流化现象,适宜于中等转速的操作条件。     

不同聚合釜生产羧基丁苯胶乳的探讨

考察了１２．７ｍ＾３和１５．０ｍ＾３聚合釜在生产羧基丁苯胶中搅拌功率、搅拌级别、桨叶端速和传热能力以对聚合温度及产品质量的影响。结果表明，在传热能力强，搅拌级别适中的情况下，聚合温度容易控制，产品质量好，转化率较镐，能耗和物耗较低。     

丁苯胶乳的稳定性研究

简要介绍了丁苯胶乳（SBL）的制备方法，探讨了乳液聚合过程中胶乳稳定的机理，考察了影响胶乳反应稳定性和储存稳定性的主要因素，如：聚合釜搅拌、聚合助剂以及储存条件等，提出了控制方法和注意事项，在工业生产中取得了良好效果。     

Influence of agitation during emulsion polymerization of acrylic–styrene latexes on end product properties

Emulsion polymerization is influenced by system turbulence due to its heterogeneous nature. System effective agitation is necessary to keep the particles in dispersed phase, to prevent flocculation, to improve mass and heat transfer, phenomena that influence the reaction mechanism and kinetics as well as the final product properties and the properties of the product based on achieved latex. This paper presents the influence of agitation on properties of the product using the obtained latex, especially on its viscosity and rheological behaviour. It also presents the influence of system initial rheology scaling up.     

Continuous emulsion polymerization of vinyl acetate. Part I: Experimental studies

An interesting feature of commercial continuous emulsion polymerization reactors is the important phenomenon of sustained oscillations. Laboratory investigations of emulsion polymerization in a continuous stirred tank reactor (CSTR) have shown that the conversion, number of polymer particles and other related properties often oscillate widely with time. These oscillations can lead to emulsifier levels too small to adequately cover polymer particles resulting in excessive agglomeration and reactor fouling. Herein is reported an extensive experimental study of vinyl acetate emulsion polymerization in a CSTR. The effects of initiator and emulsifier concentrations, mean residence time and rate of agitation on the production rate and size distribution of polyvinyl acetate latices were investigated. Domains of reactor operation which give rise to sustained oscillations and massive agglomeration of the latex are mapped which give rise to sustained oscillations and massive agglomeration of the latex are mapped out. The effect of different start-up policies on reactor transients were also investigated.     

Polymerization of vinyl chloride at reduced monomer accessibility. IV. The effect of diffusion control on polymerization rate,molecular weight,and thermal stability

The effect of diffusion control on the polymerization of vinyl chloride has been studied by observing the rate as well as the molecular weight and the thermal stability of the polymer formed. The polymerizations were performed at 97% of saturation pressure in a water-suspended system at 55°C, using emulsion PVC latex as seed and a water-soluble initiator. The monomer was charged as vapor from a storage vessel kept at a lower temperature. Characterization included determination of molecular weight distribution by GPC and viscometry, and thermal dehydrochlorination. The gas–liquid contact was varied by changing the speed of agitation and the design of the stirrer. With a propeller the polymerization rate increased with the agitation up to ca. 1000 rpm, where after it became almost constant. Simultaneously, the molecular weight and the thermal stability increased. This indicates diffusion control, and thus decreased monomer concentration, at low agitation speeds, while the polymerization becomes reaction controlled at higher speeds. By a comparison with earlier data, obtained at different pressures and under reaction control, the actual monomer concentration could be calculated, which allowed an evaluation of the mass transfer constant. The possibilities to encounter problems with diffusion control in commercial polymerization of vinyl chloride is discussed. It is demonstrated that diffusion control is utilized in continuous polymerization of vinyl chloride, which explains the lower thermal stability of such materials.     

Acrylic latices stabilized by polymerizable non-ionic surfactant

The final latex particle size is controlled by the concentration of polymerizable non-ionic surfactant NE-40 in the emulsion copolymerization of methyl methacrylate (MMA) and butyl acrylate (BA). The particle size decreases with increasing NE-40 concentration and increases with increasing persulphate initiator concentration. The dependence of particle size on the initiator concentration does not follow conventional Smith–Ewart theory, which is attributed to the bridging flocculation process during the particle nucleation period. The differences in the particle nucleation and growth stages and colloidal stability observed in the NE-40 and nonyl phenol-40 mol ethylene oxide adduct (NP-40) stabilized systems can be attributed to the different distribution patterns of surfactant molecules in the particles. Experimental data also indicate that the particle size decreases with increasing electrolyte concentration, or agitation speed. The total scrap, presumably caused by the bridging flocculation process, increases rapidly with increase in the NaCl concentration The amount of large flocs formed during polymerization is generally greater for the run operated at higher agitation speed. As expected, the latex products stabilized by non-ionic surfactants show excellent stability toward added sodium salt.     

Statistical experimental strategies approach to emulsion copolymerization of styrene and n-butyl acrylate

A batch emulsion copolymerization for the preparation of styrene-n-butylacrylate (St/BA) copolymer latexes is investigated. A series of n-butylacrylate-styrene copolymer latexes were obtained by emulsion copolymerization in the presence of K₂S₂O₈ (KPS) as initiator and with/without emulsifier (sodium lauryl sulfate). The effect of such preparation conditions as initiator concentration, the St/BA ratio, reaction temperature, agitation rate, and emulsifier concentration on the polymerization rate, particle size of copolymer latex, and molecular weight distribution of the resulting copolymer (∼ 80% conversion), respectively, is systematically studied using fractional factorial design methodology. Fractional factorial analysis indicates that the effects of the St/BA ratio, reaction temperature, emulsifier concentration, as well as the two-factor interaction of temperature and emulsifier concentration, are the key variables influencing the polymerization rate. At ∼ 80% monomer conversion, statistical analysis clearly isolates emulsifier concentration as the dominant factor affecting average particle size of copolymer latex; results also indicate that the effects of the St/BA ratio, reaction temperature, and emulsifier concentration are major effects influencing the polydispersity of polymer molecular-weight distribution. For 7.30 g KPS/100 g monomer and 500 rpm agitation rate, the conditions for minimizing molecular-weight distribution (∼ 80% conversion) occur for a reaction temperature, St/BA ratio, and surfactant concentration of 70°C, ∼ 3.59/1, and ∼ 2.08 g/100 g monomer, respectively, generating a minimum molecular-weight polydispersity of ∼ 3.0. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 551–563, 1998     

偏氟乙烯乳液聚合的气液传质效果影响因素研究

推导了表征气液传质效果的K值计算方法,并研究了聚合釜装填量、搅拌桨型和转速等因素对气液传质效果的影响。结果表明,随着聚合釜装填量和搅拌转速的增大,K值增大,气液传质效果提高;在搅拌转速大于500r/min的情况下,桨型采用上层二叶平桨、下层二叶斜桨的方式明显比单层的二叶斜桨或二叶平桨的K值大,气液传质效果好。确定了5L釜偏氟乙烯(VDF)乳液聚合必需的良好搅拌效果的条件:装填量3L,搅拌转速700r/min,桨型采用上层二叶平桨和下层二叶斜桨;VDF聚合速率达到115g/(L·h),合成出固体质量分数20%、粒径分布窄、稳定性好的聚偏氟乙烯(PVDF)乳液。     

搅拌转速对悬浮PVC树脂平均粒径的影响

在5L小釜中分别采用恒转速和变转速工艺进行氯乙烯(VC)悬浮聚合,考察粒径随转化率的变化规律,发现两者规律相似,即在低转化率时粒径随转化率的增加而逐渐增大,当转化率约为15%以后粒径几乎不再变化.同时发现搅拌转速、分散剂用量和聚合温度等对上述转化率～粒径变化规律几无影响,只是粒径大小的不同.将变转速工艺应用于大型釜生产中,考察变速时间、前转速及后转速对最终树脂粒径及其分布的影响,计算两工艺的生产能耗,发现变转速聚合除了有利于树脂颗粒的形成外,还可以降低搅拌功率的消耗,节约能源.     

VAc-BA-AA三元乳液共聚合研究

用 (NH4) 2 S2 O8-Na2 SO3氧化还原体系引发醋酸乙烯 (VAc) -丙烯酸丁酯 (BA) -丙烯酸 (AA)三元乳液共聚合 ,研究了引发剂、乳化剂、聚合反应条件对聚合转化率 ,乳液粘度和乳液稳定性的影响。实验结果表明体系动力学与经典 Smith-Ewart的乳液合理论不一致。反应速率 (Rp)随着乳化剂浓度的增加而增大 ,乳液的稳定性受乳化剂浓度的影响。聚合温度、引发剂浓度、丙烯酸的浓度对三元共聚乳液的稳定性也有影响