魔芋葡甘聚糖/ZnO纳米复合材料的制备与表征

用纳米ZnO为原料,以魔芋葡甘聚糖(KGM)为基体,采用共混法制得KGM/ZnO纳米复合物.通过傅立叶红外光谱(FTIR)、热重分析(TG)、透射电镜(TEM)等手段对该体系进行了表征.结果表明:由于纳米ZnO粒子的引入,KGM分子FTIR的某些特征峰的波数发生明显变化;纳米ZnO在复合物中的分散性较好;复合材料的热稳定性高于KGM薄膜;此外,复合材料的力学性能有所提高.     

纳米二氧化钛含量对秸秆/聚乳酸复合材料性能的影响

目的 为改善纤维增强聚乳酸(PLA)复合材料增强相与基体相之间差的界面结合。方法 以秸秆粉(SP)为填料,纳米二氧化钛(TiO2)作为界面改性剂,构建SP/PLA复合材料相容界面,通过力学性能测试、吸水率测试、扫描电子显微镜(SEM)、X射线衍射(XRD)和热重分析法(TGA)等表征手段,探究不同含量纳米二氧化钛对SP/PLA复合材料力学性能和界面相容性的影响。结果 研究发现,纳米二氧化钛的质量分数为2.0%时,复合材料的拉伸强度和弯曲强度分别达到42.78 MPa和91.25 MPa,其耐水性能、结晶度、耐热性能也达到最好。结论 纳米二氧化钛可有效提高秸秆/聚乳酸复合材料的性能。     

导电PMMA/ATO纳米复合材料的制备及性能

以掺锑二氧化锡(ATO)粉为导电填料,聚甲基丙烯酸甲酯(PMMA)为基体,采用原位聚合法制备了导电PMMA/ATO纳米复合材料;分析了ATO粉的预处理对复合材料导电性能的影响,并对其热性能和力学性能进行了研究。结果表明,延长球磨时间,可大幅度降低复合材料的体积电阻率;ATO纳米粒子的加入使PMMA主分解温度范围变窄,残余量增大,热稳定性提高;随着纳米粒子含量的增加,复合材料的储能模量提高,玻璃化温度降低。第二分相促使ATO颗粒在基体中形成明显的导电网络结构,使导电性能得到进一步提高。     

纳米AT/NBR复合材料的制备与研究

纳米凹凸棒土(AT)是一种天然纳米填料,对其性质和改性方法的研究直接关系到它的应用性能和工业前景。采用熔融共混法制备了纳米凹凸棒土/丁腈橡胶(AT/NBR)复合材料,并进行了力学性能测试。具体考察了增塑剂、硅烷偶联剂、不同凹凸棒土填充量、改性方法等对复合材料力学性能的影响。结果表明,经Si-69改性的AT可以显著提高NBR的力学性能。     

魔芋葡甘聚糖/凹凸棒土复合纤维的试制及性能

采用凹凸棒土(AT)对魔芋葡甘聚糖(KGM)进行共混改性,制备了KGM/AT共混溶液,以95%的酒精为凝固浴,利用注射器模拟湿法纺丝制备了KGM/AT复合纤维,通过纤维的纵向形态结构观察初步研究了AT对KGM溶液可纺性的影响,并对纤维的力学性能、吸水性能进行了测试。结果表明,KGM/AT溶液具有一定的可纺性,但是在AT用量较高时,纤维呈现出的弱节、疵点等结构不均匀性更为明显;适量的AT经过适当的牵伸有助于分子链取向,可以提高复合纤维的力学性能;此外,AT用量较低时有助于KGM纤维吸水,最高吸水倍率提高了近50%。     

PP/无卤阻燃剂/AT复合材料的制备及性能研究

以聚丙烯(PP)为基体树脂,聚磷酸铵(APP)和三聚氰胺(MA)为无卤阻燃剂,无机矿物质凹凸棒土(AT)为协同阻燃剂,采用熔融共混的方法制备了PP/无卤阻燃剂/AT复合材料。采用扫描电子显微镜(SEM)对复合材料的微观形貌进行了研究;通过极限氧指数(LOI)和热重分析(TG)研究了材料的阻燃性和热稳定性;通过对复合材料拉伸强度、冲击强度、弯曲强度以及断裂伸长率等的测试,研究了材料的力学性能。结果表明,无卤阻燃剂APP、MA和AT可在PP体系中均匀分散;阻燃剂的加入使得复合材料的力学性能降低,但AT的加入对又可显著提升其力学性能;阻燃剂与AT的协同作用可使复合材料的热稳定能和阻燃性能明显改善,材料的极限氧指数可达到27.3,提高了约40%。     

聚乙烯和纳米蒙脱土与淀粉共混改性研究进展

综述了近年来纳米蒙脱土和聚乙烯与淀粉共混改性制备可降解复合材料的方法和加工工艺。此外,还综述了淀粉的表面改性和相容剂加入、纳米蒙脱土的剥离和在基体树脂中的分散对共混复合材料的力学性能、热性能、耐水性能及材料的微观结构的影响。     

硅酸盐纳米纤维增强橡胶复合材料的结构与性能

利用天然针状硅酸盐——凹凸棒石(AT)的结构特点, 采用机械共混法并结合原位改性技术制备了一系列硅酸盐纳米纤维/橡胶复合材料, 研究了复合材料的结构与性能, 分析了针状硅酸盐良好增强效果的内在机制。借助硅烷偶联剂的原位改性和混合过程中的机械剪切力, AT微米聚集体被解离成长径比为10~30的纳米纤维分散在橡胶基体中, 纳米复合材料表现出短纤维/橡胶复合材料(SFRC)的应力-应变特性和明显的力学性能各向异性。而且, AT/橡胶纳米复合材料具有优良的高温模量和加工性能。AT的优良的增强效果来源于AT的纳米分散和良好的纤维-橡胶界面结合。      

功能化石墨烯/弹性体协同强韧化聚丙烯纳米复合材料的制备和性能研究

利用乙二胺功能化石墨烯(GS-EDA)为纳米填料,马来酸酐接枝乙烯-辛烯共聚物(POE-g-MAH)弹性体为增韧剂,经熔融共混法制备了PP/POE-g-MAH/GS-EDA纳米复合材料。并采用红外光谱(FTIR)、扫描电子显微镜(SEM)、示差扫描量热仪(DSC)、热失重分析(TGA)、力学性能、热变形温度和熔融指数测试分别对填料和所得纳米复合材料的结构和性能进行了测试和表征。研究表明,EDA已成功接枝于石墨烯的表面上;POE-g-MAH的酐基与GS-EDA的氨基发生了作用改善了共混体系的界面相容性并促进了GS-EDA在PP基体中的分散性。当GS-EDA含量为0.5%(质量分数)时,复合材料的拉伸强度、弹性模量和冲击强度分别较PP/POE-g-MAH提高了25.2%、32.5%和26.9%,此时复合材料的综合力学性能也最好。添加GSEDA提高了复合材料的结晶温度、熔融温度和结晶度。GS-EDA的加入使PP/POE-g-MAH/GS-EDA复合材料的热稳定性提高,而熔融指数逐渐降低。     

阻燃级黄麻短纤维/聚乳酸复合材料的制备及性能研究

采用具有良好降解性的黄麻短纤维作为增强材料,生物可降解材料聚乳酸作为基体,制备了可降解的黄麻/聚乳酸复合材料。对复合材料的力学性能,耐热性能以及阻燃性能等进行了测试,结果表明,相对与纯聚乳酸,黄麻纤维的加入使复合材料的力学性能和耐热性能有明显提高,阻燃体系的加入使复合材料具有良好的阻燃性能,可达到UL94V0级,但阻燃剂的加入一定程度上降低了复合材料的力学性能及热变形温度。     

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 ...