含固相淀粉的反相乳液体系稳定性研究

以液体石蜡为油相,烯类单体的水溶液为水相,Span80和OP-4为复配乳化剂,制备反相乳液。考察了乳化剂H LB值及浓度、水相体积分数Φ、单体用量及固相淀粉颗粒对乳液类型及稳定性的影响规律。实验结果显示:乳化剂H LB值对乳液类型及稳定性影响显著,在H LB=4.3~6.1范围内,能形成稳定的油包水(W/O)型乳液;乳化剂最佳浓度即其质量分数为5%~8%;Φ应小于50%;单体将导致反相乳液稳定性降低;固体淀粉的存在有利于形成W/O型反相乳液,并且能使反相乳液体系的稳定性明显提高。     

淀粉丙烯酰胺反相乳液体系的稳定性及接枝共聚反应

以Span80和Tween80为复合乳化剂,制备了稳定的W/O型淀粉丙烯酰胺反相乳液。探讨了乳化剂HLB值、油水比、乳化剂用量对乳液类型及稳定性的影响,得到最佳配方:乳化剂HLB值6.49、油水比1∶1、乳化剂用量3%。在此反相乳液体系中,成功进行了淀粉丙烯酰胺接枝共聚反应,通过正交实验得到最佳工艺条件为反应温度50℃、反应时间2 h、引发剂浓度0.0175 mol/L、单体与淀粉质量比1.5。在此实验条件下合成的淀粉丙烯酰胺接枝共聚物之聚合率和接枝效率分别可达95.46%和95.10%以上。     

羧甲基化植物胶粉反相乳液的稳定性

研究了含固相羧甲基化植物胶粉的反相乳液的稳定性。以span-80和op-10为复合乳化剂,液体石蜡为连续相,水溶性单体丙烯酰胺和羧甲基化植物胶粉为水相制备了乳液体系,考察了乳化剂亲水亲油平衡值(HLB)、乳化剂浓度、水相比、植物胶粉含量、pH值及温度对乳液稳定性的影响。结果表明,胶粉用量和pH值影响较小,最佳的稳定条件为:HLB为7.36,乳化剂浓度为0.045g/mL油相,水相比小于60%,温度低于60℃。     

硫化锌纳米粒子的微乳液合成

介绍了微乳液制备纳米粒子的基本原理。对影响微乳液体系形成的主要因素如油相、水相、表面活性剂种类及用量等进行了研究，以表面活性剂TWEEN80和SPAN80作乳化剂，通过调整其比例控制乳化剂的HLB值，制备了乳化剂浓度为0.3mol/L、水/乳化剂比为6：1的W/O型庚烷/ST80/水微乳液体系。在此微乳液中制备了ZnS纳米粒子，采用TEM和XRD对超细样品的结构进行表征，表明得到的样品为β型立方晶系ZnS粒子、粒子粒径10-30nm。     

聚碳酸亚丙酯乳液的制备与性能

采用直接乳化法制备聚碳酸亚丙酯(PPC)乳液,研究乳化剂亲水亲油平衡(HLB)值、连续相聚乙烯醇(PVA)浓度对乳液性能的影响。研究表明,当乳化剂HLB值在12.6~16.0之间时,均可制得PPC乳液。PVA质量分数高于1%则会导致PPC乳液稳定性下降。当乳化剂HLB值为13.0时,乳液白色泛蓝光,电导率为96.2μS/cm,固含量为3.73%,5000r/min下离心10min既无沉淀也无分层产生,静置半月无明显变化,粒径分布曲线分别在2μm和30μm处有2个独立的峰。     

SiO_2/聚丙烯酰胺核壳复合材料的制备研究

首先使用KH-550对纳米SiO_2进行表面改性,通过测试其亲油化度(HD)值以及控制相关影响因素得到的最佳改性条件为:KH-550占单体质量分数的6%,反应温度为30℃,反应时间为1.5h。然后通过Schulman法配制含有改性纳米SiO_2和单体丙烯酰胺的微乳液,通过其表观透明度以及稳定性优选出的微乳液配方为:V(油)∶V(水)=3∶2,ω(乳化剂)=25%(占油相),ω(助乳化剂)=25%(占油相),ω(单体)=50%(占水相)。最后通过反相微乳液聚合制备出核壳结构的SiO_2/聚丙烯酰胺复合材料,对其进行了红外光谱分析和透射电镜分析表征。     

双连续相微乳液聚合制备多孔材料

反相(W/O)或双连续相微乳液聚合制备多孔材料是近年研究的热点。研究了双连续相微乳液聚合制备多孔吸油材料:以甲基丙烯酸甲酯、甲基丙烯酸丁酯为共聚单体(油相),水/乙醇为混合水相,偶氮二异丁腈为引发剂,十二烷基硫酸钠为乳化剂,调节油相和水相比例,配制出双连续相微乳液。聚合在无搅拌下进行。对聚合物进行SEM观测表明,当混合水相含量在30%～43%(质量分数,下同)区域内,得到连续开孔材料。仅对多孔材料制备工艺进行研究分析及孔特性进行了表征,吸油材料的研究将在后续文章中报道。     

含氟乳液的持续微波法合成及性能

以非离子型乳化剂OP-10、离子型乳化剂十二烷基硫酸钠(SDS)与含氟乳化剂S200为复合乳化剂,通过持续微波法合成甲基丙烯酸甲酯、丙烯酸丁酯与甲基丙烯酸六氟丁酯的三元含氟乳液。用持续微波辐射法的效率高,100W功率下反应2min15s,单体转化率为92.8%。乳化剂质量分数增加,乳胶粒粒径逐渐减小;含氟单体质量分数增加,乳胶粒粒径逐渐上升;乳胶粒粒径随着微波功率的增加先增加,在200W处出现转折。乳液的离心稳定性与微波辐射的功率及能量大小有关;含氟单体的增加降低了乳液的稳定性。用接触角表征含氟乳胶膜的防水性能,当氟单体的质量分数为25%时,接触角能够达到84°。     

反相乳液法制备单分散性Fe3O4微粒的研究

为制备单分散性的Fe3O4微粒,采用反相乳液法,以Fe2 与Fe3 按n(Fe2 ):n(Fe3 )=1:2配成的水溶液作为水相,十二烷基磺酸钠为乳化剂,液体石蜡和水溶液形成油包水型乳液,用NaOH共沉淀.实验考察了油/水体积比、搅拌速度、乳化剂及碱用量、乳化时间的影响.结果表明,较佳的条件是:在V(石蜡):V(水)=6:1,1030r/min的搅拌速度下,乳化剂的量为4.5g/L,乳化20min后,用超过理论用量5%的氢氧化钠共沉淀.用粒度仪和磁天平表征所得Fe3O4,数均粒径为2μm,98%的粒径分布在1～5μm,质量磁化率为2.60×10-2emu/g.     

利用SPG膜制备O/W型乳液实验研究

利用孔径为0.6μm的SPG(Shirasu Porous Glass)多孔微滤膜,以异辛烷为分散相、pH=7的磷酸盐缓冲水溶液为连续相、以SDS(十二烷基硫酸钠)和PVA(聚乙烯醇)分别为水相乳化剂和稳定剂,制备了O/W型乳液,研究了操作条件对乳液性能包括液滴大小及分布的影响关系.当跨膜压差在0.12~0.16 MPa时,连续相流速分布在0.20~0.40 m/s时,乳化剂浓度在其临界胶束浓度(CMC)之上时,乳液的单分散性较好.由于乳液具有良好的稳定性和单分散性,可用于多相界面酶催化反应.     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...