丙烯酸酯软硬单体含量对PU/PA复合乳液及其表面施胶性能的影响

采用原位无皂乳液聚合法制备了水性聚氨酯-丙烯酸酯(WPUA)复合乳液。分析了软硬单体比例对WPUA乳液粒径、粘度,对胶膜的凝胶率、吸水率和力学性能的影响,并研究了WPUA乳液对纸张的增强作用。研究表明,随着m(MMA)增大,胶粒粒径增大,乳液粘度下降,胶膜凝胶率上升,吸水率先下降后上升,且当m(MMA)为14.37%时,胶膜力学性能最佳。以质量分数为1%的WPUA乳液进行表面施胶,施胶度达37.47s,湿强度达31.61%。当m(MMA)为8.64%时,耐折度达54次。     

水性聚氨酯的合成、改性及其在烟包涂料上的应用

为了满足烟包印刷行业低VOC含量的要求,以耐高温聚酯二元醇(NCL2000)作为软段,4,4′-二环己基甲烷二异氰酸酯(HMDI)、亲水扩链剂二羟甲基丁酸(DMBA)、扩链剂1,4-丁二醇(BDO)、后扩链剂乙二氨基乙磺酸钠(AAS)、封端剂丙烯酸羟乙酯(HEA)、甲基丙烯酸甲酯(MMA)作为硬段,制备了无三乙胺、零VOC的水性聚氨酯-丙烯酸酯(WPUA)复合乳液,研究了MMA对WPUA复合乳液的制备及胶膜性能的影响,并通过傅里叶变换红外光谱(FTIR)、热重分析(TGA)等测试手段对WPUA乳液及其胶膜的结构和性能进行分析。结果表明,随MMA添加量增大,WPUA复合乳液平均粒径增大,WPUA胶膜的吸水率随之减小。当热失重率为50%时,MMA改性后的WPUA胶膜比纯水性聚氨酯(WPU)胶膜的分解温度提高了52.85℃。     

GMA改性无溶剂阴离子聚氨酯/丙烯酸酯复合乳液的合成及性能研究

采用原位聚合法,制备得到了无溶剂阴离子聚氨酯/丙烯酸酯(WPUA)复合乳液,系统地研究了GMA用量对WPUA乳液及其膜性能的影响。结果表明,当m(GMA)=10.2%时,WPUA乳液粒径较小且分布窄,平均粒径为141.1nm,且聚合物具有良好的热稳定性,涂膜呈现良好的耐水性和耐醇性,吸水率低至6.85%,涂膜硬度达到2H,附着力达到0级,耐冲击合格。     

光固化聚氨酯-丙烯酸酯乳液的制备及对纸张的增强作用

以异佛尔酮二异氰酸酯(IPDI)、聚己内酯二元醇(PCL1000)、二羟甲基丁酸(DMBA)、季戊四醇三丙烯酸酯(PETA)和丙酮等为原料合成了水性光固化聚氨酯-丙烯酸酯复合乳液,并利用该乳液对纸张进行表面施胶。通过傅立叶红外光谱(FT-IR)和光散射对乳液的结构进行了分析;研究了n(NCO)/n(OH)比值(R值)对乳液和涂膜耐水性和力学性能的影响,紫外光(UV)固化前后对纸张物理性能的影响。结果表明,当n(NCO)/n(OH)=1.6,m(PETA)=12.6%时,乳液具有良好的稳定性,涂膜呈现良好的耐水性和力学强度,吸水率降至3.66%;UV固化后纸张湿强度提高41.65%,纸张环压指数达到5.25N.m/g。     

自交联聚氨酯-丙烯酸酯杂化乳液的制备及其膜性能研究

以异佛尔酮二异氰酸酯(IPDI)、聚己内酯二醇(PCL)、二羟甲基丁酸(DMBA)、双丙酮丙烯酰胺(DAAM)等为主要原料,采用乳液聚合法合成了常温自交联聚氨酯-丙烯酸酯杂化乳液。通过傅里叶红外光谱(FT-IR)、激光粒度分析仪、热重分析(TGA)等研究了DAAM单体含量、n(DAAM)/n(ADH)比值对乳液及涂膜性能的影响。结果表明,当m(DAAM)=2%,n(DAAM)/n(ADH)=2∶1时,所得杂化乳胶膜的耐水性、力学性能和热稳定性最优。     

丙烯酸羟乙酯对自交联苯丙胶乳性能的影响

以苯乙烯(St)、丙烯酸丁酯(BA)、甲基丙烯酸甲酯(MMA)、丙烯酸(AA)、丙烯酸羟乙酯(HEA)为原料,通过乳液聚合法合成固含量约为40%的自交联苯丙胶乳纸张涂布剂。考察了不同HEA用量对乳液及其膜性能的影响。结果表明,当m(St)/m(BA)=1∶2,w(MMA)=11.5%,w(AA)=6.9%,w(HEA)=11.5%时,合成的乳液稳定,粒径较小且分布均匀,乳液呈现假塑性流体的流变性质;随着交联单体HEA用量的增加,乳液黏度显著增大,胶膜吸水率最低可达4.1%,膜的力学拉伸强度可由1.7 MPa提高到4.7 MPa,同时聚合物的热稳定性可最大提高31.3℃。     

亲水SiO2改性水性聚氨酯-聚丙烯酸酯的制备及性能

为了提高水性聚氨酯材料的耐热性、耐化学试剂性及力学性能,利用甲基丙烯酸甲酯(MMA)作为聚氨酯预聚合的连续相,同时采用羧酸型以及磺酸型亲水扩链剂,乳化时引入反应性的亲水性纳米二氧化硅(WSiO2),通过无有机溶剂法制备了稳定的耐温水性聚氨酯-聚丙烯酸酯(WPUA)乳液。利用透射电镜、红外光谱、X射线衍射和热重等手段研究了WPUA乳液及其膜的结构和性质。结果表明:随着样品中WSiO2含量的增加,WPUA乳液的平均粒径增大,WPUA膜的光泽度下降,硬度、附着力增加,WPUA薄膜的硬度和附着力增加,拉伸强度值先上升后下降,最佳WSiO2添加量为1%。适量的WSiO2可以改善WPUA材料的耐热行为。当热分解率为50%时,WSiO2改性后WPUA的分解温度比改性前提高了39℃。WSiO2改性使WPUA的力学和耐化学试剂性也得到了改善。     

KH550交联改性无溶剂聚氨酯/丙烯酸酯乳液的合成应用

采用原位聚合法,合成了一系列γ-氨丙基三乙氧基硅烷(KH550)改性的无溶剂阴离子型聚氨酯/丙烯酸酯复合乳液(WPUA)。重点考察了KH550用量对WPUA乳液及涂膜性能的影响,通过红外光谱(FT-IR)、热重分析(TGA)、粒度分析仪(DLS)、原子力显微镜(AFM)、吸水率测试等对其相关性能进行了表征。结果表明,KH550反应到聚氨酯链段上且当m(KH550)=1.05%(占整个反应物总量,下同)时,WPUA乳液稳定性较好,平均粒径为104.5nm,其热稳定性也较佳,涂膜表面平坦且较规整,硬度可达2H,耐冲击性合格,附着力达到0级,吸水率低至8.57%。     

两性丙烯酸酯聚合物乳液表面施胶剂的制备及应用

以PVA为分散剂,甲基丙烯酸(MAA),苯乙烯(St),丙烯酸丁酯(BA),甲基丙烯酰氧乙基三甲基氯化铵(DMC)为单体,通过无皂乳液共聚反应制备了一种两性聚合物乳液表面施胶剂。讨论了反应条件的变化对乳液稳定性及施胶应用效果的影响,确定了较佳的合成条件:采用种子聚合法,n(DMC)/n(MMA)/n(BA)/n(St)=1∶1.5∶1.6∶2.4,w(KSP)=0.6%,反应温度85℃,反应时间4 h。DSC测量出玻璃化温度为56.8℃;TEM显示乳胶粒呈球状;粒径分析显示乳液平均粒径为107 nm。以2.0%的聚合物乳液进行表面施胶时,可使施胶度达到13 s,拉毛速率达到2.9 m/s。     

自交联苯丙胶乳纸张涂布剂的合成及其膜性能研究

以苯乙烯(St)、丙烯酸丁酯(BA)、甲基丙烯酸甲酯(MMA)、丙烯酸(AA)、丙烯酸羟乙酯(HEA)为原料,通过乳液聚合法合成固含量约为40%的轻度交联苯丙胶乳纸张涂布剂。考察了不同单体用量对乳胶膜机械性能的影响。结果表明,当m(MMA)=11.5%,m(AA)=6.9%,m(HEA)=11.5%,m(St)/m(BA)=1∶2时,乳胶膜呈现良好的机械性能,乳液粒子尺寸较小且分布窄,平均粒径为128.9nm;且聚合物具有良好的耐热性。     

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.     

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...     

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.     

The Research of Anti-Wear Properties of Organomolybdenum Compounds in the Engine Oils

A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils.     

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.     

Synthesis of Alumina-Zirconia Nanocomposites by Solgel Process

Al₂O₃-ZrO₂ nanocomposites were developed starting with the solgel process. Composite alumina-zirconia nanopowders were synthesized from metallorganic precursors (Aluminium secondary butoxide and zirconium Iso propoxide) using the solgel process. The parameters affecting the synthesis—solvent, concentration of precursor, R/H ratio (i.e., dilution of water in solvent)—were varied as also the temperature and pH. BET and TEM were used to measure nanosize. Diffuse reflectance spectroscopy and also qualitative optical absorption led to identical particle size estimate. The variation of process parameters was used to study the effect and interdependence of process parameters. Artificial Neural Networks was used to rigorously analyze the process. Although this led to confirmation of interdependence of parameters, the presence of a single overwhelming solvent variable was also established. Then the optimal process was used to synthesize more nanopowder. To produce bulk nanocomposite the nanopowders were sintered by varying the temperature and time period. The sintered lithoids were probed with a vickers hardness tester to measure elastic modulus, hardness, and fracture toughness. The results showed high elastic modulus, modest hardness, and very high fracture toughness.     

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.……     

Friction Stir Processing Strategies for Uniform Distribution of Reinforcement in a Surface Composite

Friction stir processing (FSP) is an important technique for preparing surface composites. Fabricating defect-free surface composites with uniform particle distribution by FSP is a challenging task. In this study, silicon carbide particles reinforced AA5083 alloy surface composites was fabricated using different FSP strategies including variation in process parameters, dual-tool processing and tool offset overlapping. Material flow of the processed material with reinforcement particles demonstrated that the distribution of particles was influenced by the stirring action of the probe as well as the extrusion of the plasticized material due to the movement of the tool. Process parameters, particularly rotational speed, showed a dominant influence on the distribution of silicon carbide particles.