热退火-选择性溶胀成孔法制备PS-b-PNIPAAm/PVDF纳米均孔复合膜

将两亲嵌段共聚物聚苯乙烯-b-聚(N-异丙基丙烯酰胺)(PS-b-PNIPAAm)涂覆在聚偏氟乙烯(PVDF)膜上构建复合膜,采用热退火方式控制PS-b-PNIPAAm的微相分离行为,并以异丙醇为溶剂,利用选择性溶胀成孔法制备PS-b-PNIPAAm/PVDF复合膜,研究了不同退火温度对PS-b-PNIPAAm薄膜分相行为及PS-b-PNIPAAm/PVDF复合膜形貌的影响。结果表明:通过热退火和选择性溶胀成孔法能够得到纳米均孔复合膜,热退火温度对复合膜表面的形貌有较大影响。     

聚苯乙烯-聚甲基丙烯酸甲酯两嵌段共聚物薄膜在超临界二氧化碳和丙酮溶剂耦合作用下的形貌演化

以聚苯乙烯-聚甲基丙烯酸甲酯(PS-b-PMMA)两嵌段共聚物薄膜为考察对象,首先对比研究了PS-b-PMMA薄膜分别在丙酮溶剂和超临界二氧化碳(scCO_2)环境中退火的形貌演变,进而提出利用scCO_2和丙酮溶剂的耦合作用调控嵌段共聚物薄膜的相转变。实验结果表明,利用scCO_2和丙酮溶剂的耦合作用,能够显著缩短嵌段共聚物薄膜的有序-无序相转变时间,得到高度有序的分相形貌。     

PS-b-PMMA-b-PBMA薄膜自组装形貌研究

采用原子转移自由基聚合技术制备了聚苯乙烯-b-聚甲基丙烯酸甲酯-b-聚甲基丙烯酸丁酯三嵌段共聚物。利用原子力显微镜考察了该三嵌段共聚物薄膜相结构在不同溶剂气氛中随时间的演变。结果表明:在聚苯乙烯的选择性溶剂二甲苯(甲苯)气氛中,共聚物微相结构实现了由球状结构到棒状结构的转变,并最终形成较为有序的条纹形貌。在共溶剂四氢呋喃(氯仿)气氛中,微相结构由与基底平行的层状结构演变为棒状结构。另外,通过热溶剂蒸汽退火,制备了特征尺寸为28nm、长程有序的条纹形貌。     

PEO-b-PS嵌段共聚物的合成与有序纳米膜的制备

以聚环氧乙烷-溴(PEO-Br)大分子引发剂引发苯乙烯(St)的原子转移自由基聚合(ATRP),制备了聚环氧乙烷-b-聚苯乙烯(PEO-b-PS).1H NMR分析表明嵌段共聚物中聚环氧乙烷嵌段和聚苯乙烯嵌段的数均分子量分别是5500和37000,PEO的质量分数为12.9％.考察了旋涂环境和溶剂熏蒸后处理方法对此嵌段共聚物薄膜形貌的影响,结果表明在PS的良溶剂和PEO的良溶剂共同存在下旋涂成膜,并经过两种良溶剂共同蒸汽的后处理,PEO-b-PS嵌段共聚物可以制得具有规则纳米圆柱图案的薄膜.     

蝌蚪型POSS嵌段共聚物的合成及其质子交换膜的性能

以聚倍半硅氧烷(POSS)为引发剂,用原子转移自由基聚合方法(ATRP)合成聚甲基丙烯酸甲酯与聚苯乙烯嵌段共聚物(PMMA-b-PS)为臂的蝌蚪型POSS嵌段共聚物,并使用红外光谱、核磁共振及GPC等手段分析其结构。结果表明,合成的蝌蚪型POSS嵌段共聚物结构规整。以蝌蚪型POSS嵌段共聚物为基体制备质子交换膜,研究了离子交换容量、吸水率及溶胀率,质子传导率及热性能。结果表明,蝌蚪型POSS嵌段共聚物质子交换膜在高温具有较高的质子传导率、较高的初始热分解温度和耐高温性能。     

两亲嵌段共聚物PS-b-PAA自组装薄膜的表面形貌与结晶性能研究

采用溶液浸渍-提拉法制备了两亲性嵌段共聚物PS-b-PAA自组装薄膜,并利用图像分析仪和X射线衍射仪研究了聚合物薄膜的表面形貌和结晶性能.研究结果表明,PS-b-PAA的溶液浓度和嵌段长度通过影响溶液中形成的反胶束数目和粒径进而造成溶剂挥发过程中反胶柬在扩散动力学上的差异,最终得到不同形貌的嵌段共聚物薄膜.结晶性能研究结果表明,室温下PS-b-PAA在玻璃基板表面的结晶是一种受膜厚影响、动力学控制的受限结晶过程.当溶液浓度达到0.1g/mL时,可制备出致密的结晶性嵌段共聚物薄膜.     

含氟嵌段共聚物蜂窝状多孔膜制备与表征

采用原子转移自由基聚合(ATRP)方法,合成聚苯乙烯(PS)大分子引发剂,再引发甲基丙烯酸十二氟庚酯制备嵌段共聚物(PS-b-PDFHMA)。将嵌段共聚物与纳米二氧化钛(TiO_2)复合,利用静态呼吸图法制备抑菌性多孔膜。通过傅里叶变换红外光谱、核磁共振氢谱、凝胶渗透色谱等对嵌段共聚物结构、组成及相对分子质量进行分析和表征;利用扫描电子显微镜对多孔膜表面形貌和膜层结构进行观察;利用接触角测试仪和微生物粘附实验研究多孔膜表面润湿性及对微生物粘附的影响。结果表明,以水滴为模板的多孔膜相较于不含孔薄膜疏水性有一定改善,但细菌粘附量提高,与TiO_2复合后,多孔膜表面粗糙度上升,水接触角可达136°,其表面细菌粘附量明显下降。     

PS-b-PAA/PLA有序多孔抗菌膜

利用原子转移自由基聚合(ATRP)合成具有可控结构的嵌段共聚物PS-b-PtBA,用GPC、1 HNMR对产物的分子量及其分布和嵌段组成进行了表征.将产物在酸性条件下水解得到两亲性嵌段共聚物PS-b-PAA,并用FT-IR、1 HNMR和滴定分析对水解产物进行表征.用水滴模板法,以该两亲性嵌段共聚物为表面活性剂辅助聚乳酸(PLA)形成有序多孔膜,探讨PAA链长、PS-b-PAA质量分数以及溶液浓度对膜孔形貌的影响,以制备得到的PS-b-PAA/PLA复合多孔膜为模板负载入抗菌剂茶多酚(TP),制备得抗菌性薄膜,结果表明膜孔的有无以及大小会对负载的抗菌剂的量有影响,从而影响薄膜的抗菌性能.     

多壁碳纳米管/SBS复合材料的制备及其渗流特性

以多壁碳纳米管(MWNTs)为导电填充物,以苯乙烯-丁二烯三嵌段共聚物热塑性弹性体(SBS)为基体材料,制备了导电高分子混合物薄膜,考察了采用不同的溶剂和成膜工艺对薄膜表面形貌的影响,同时通过电流/电压特性的测试,得到不同的MWNTs浓度下MWNTs/SBS混合材料的电渗流特性,其渗流区在6～9wt%之间.我们还初步研究了所得混合材料的电阻值受温度的影响,发现其温阻特性具有很强的时间迟滞性.     

嵌段共聚物PCL-b-PMMA薄膜的微相分离形貌

通过开环聚合(ROP)和原子转移自由基聚合(ATRP)制备了不同嵌段结构的嵌段共聚物PCL-b-PMMA,使用核磁共振(1H-NMR)和凝胶渗透色谱(GPC)对其结构进行了表征,通过原子力显微镜(AFM)研究了嵌段共聚物薄膜的微相分离形貌。结果表明,嵌段共聚物发生了微相分离,聚ε-己内酯(PCL)链段形成柱状微区;PCL链段体积分数较低时,薄膜表面以聚甲基丙烯酸甲酯(PMMA)链段聚集为主,但未在PCL柱状微区上方形成覆盖,从而在薄膜表面形成孔洞;随PCL链段体积分数增加及PMMA链段分子量下降,PCL柱状微区面积增加,向薄膜表面迁移并逐渐形成覆盖,造成薄膜表面孔洞消失。     

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.……     

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...     

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.     

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.……     

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.     

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.     

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 ...