循环老化中HDF的甲醛释放规律的研究

在使用过程中，HDF的力学强度不仅会降低，而且其甲醛释放量也会发生变化。采用气候箱老化法处理HDF，按照国家标准跟踪测试HDF的理化指标，探索HDF甲醛释放的规律，为消除甲醛污染和改善室内环境提供理论依据。试验结果表明，在湿热作用下，HDF的力学指标下降到一定程度后趋于平稳，而甲醛释放量与老化周期成指数关系，并使HDF甲醛释放量长期保持在较高水平。     

人造板甲醛成因及检测方法浅析

本文介绍人造板产牛甲醛的原因，分析了人造板甲醛释放量检测过程中影响测定结果的主要因素，就人造板甲醛释放量的三种检测方法（穿孔萃取法、干燥器法和气候箱法）进行了分析。     

脲醛树脂胶黏剂改性研究进展:分子结构优化与改造

脲醛树脂(UF)胶接制品因长期释放甲醛,是家居环境污染的主要来源。目前,生产企业普遍通过降低甲醛与尿素摩尔比生产UF树脂以减轻胶接制品产生的甲醛污染,但摩尔比下降会造成UF树脂支化结构大量减少、固化交联度下降,最终导致树脂胶合强度和耐水性能变差。UF树脂性能好坏的关键在于其微观结构的形成,从分子水平优化与改造UF树脂结构是实现其固化速率、甲醛释放量和胶合性能之间平衡的有效方法。文中总结了利用三聚氰胺、乙二醛、树枝状大分子等改性剂优化与改造UF树脂结构的作用机理,阐述了不同改性方法与改性工艺对UF树脂胶固化性能、胶合强度及胶接制品甲醛释放量的影响,最后提出了改性UF树脂胶黏剂未来研究与发展面临的主要挑战。     

浅析人造板甲醛释放量的检测方法

人造板材是现代装饰装修中最常用产品之一，人造板释放的甲醛对人体的危害性明显。对人造板甲醛释放量的检测，是产品质检的一项重要内容。本文就人造板甲醛释放量的三种检测方法（穿孔萃取法、干燥器法和气候箱法）进行分析，以提高检测准确度。     

解析气候箱法测板材中甲醛释放量

正一、检测范围及标准气候箱法测甲醛适用于饰面人造板,是测板材甲醛释放量的仲裁分析方法。依据标准:GB/T17657-2013《人造板及饰面人造板理化性能试验方法》;GB18580-2001《室内装饰装修材料、人造板及其制品中甲醛释放量》。二、检测原理将1m2表面积的样品放入温度、相对湿度、空气流速和空气置换率控制在一定值的气候箱内,甲醛从     

气候箱法测定家具甲醛释放量与实际工况差异的探讨

本文通过1m3气候箱法测定家俱甲醛释放量的实验数据,对比平行试样采用干燥器法在温度递升的控制环境条件下的检测数据,进行分析研究,从而得出1m3气候箱法仅限制在恒定温度点的测定值与家俱实际工况下甲醛释放量的明显差异,及家俱甲醛释放量随温度递升而发生变化的大致规律。旨在阐述家俱甲醛释放量应在不同设定温度点进行检测,或以两种以上组合方法进行测定,以尽可能客观地模拟或重现家俱在实际工况下的甲醛释放状态,从而体现相关检测结果的客观性、公正性和实用性。     

木质素磺酸钠预聚体改性脲醛树脂研究

脲醛树脂(UF)胶粘剂的胶合强度高、价格低廉,在木材加工业应用广泛,但是UF化学结构不稳定,在使用过程中会不断释放出甲醛,危害环境。以造纸行业的废弃物——木质素磺酸钠为原料,通过纯化-活化-预聚的工艺,合成了一种新型木质素磺酸钠预聚体。该预聚体结构中的多个胺基可与脲醛树脂中的羟甲基和游离甲醛反应,改善了UF不稳定结构,减少了甲醛来源,同时可以提升树脂的胶合强度。使用上述预聚体改性的UF胶粘剂制备的胶合板粘结强度高,甲醛释放量达到E0级标准,小于0.5mg/L。     

乙丙橡胶在碱液中界面老化的初步研究

采用表面粗糙度测试、傅里叶变换红外光谱(FTIR)和X射线光电子能谱仪(XPS)等方法研究了在碱液环境中乙丙橡胶表面老化前后的变化规律。结果表明,随着老化时间的延长,橡胶表面粗糙度逐渐增大。XPS测试结果表明乙丙橡胶表面C-C含量降低,而C=O和O=C-O含量增加,这是乙丙橡胶老化的标志。老化后乙丙橡胶的FTIR测试结果表明,在1742cm-1和1162cm-1处对应于C=O和C-O-C的伸缩振动,进一步证实了XPS的结果。     

有机蒙脱土插层脲醛（OMMT／UF）树脂的制备与性能研究

实验采用十六烷基三甲基溴化铵(CTAB)和十二烷基三甲基溴化铵(DTAB)为改性剂,对蒙脱土(MMT)进行了有机化处理,得到了有机蒙脱土(OMMT),并采用聚合反应过程中的插层复合法制备了有机蒙脱土插层脲醛树脂(OMMT/UF)胶粘剂。通过XRD和SEM对OMMT的结构变化进行表征,结果表明:有机改性剂已进入OMMT的层间,OMMT具有较MMT优良的层间结构。考察了OMMT的投加量对OMMT/UF胶粘剂的各项性能的影响,结果表明OMMT加入量越大,越有利于增强除固化时间以外的各项性能,与UF胶粘剂相比,当OMMT质量分数为3%~5%时,得到的OMMT/UF胶粘剂的表观粘度提高了2倍,耐水时间增加了100 min左右,甲醛释放量降至了5.6 mg/L以下,但是固化时间则增加了近1倍。将OMMT/UF胶粘剂用于胶合板的压制,发现OMMT/UF胶粘剂能够改善板材的强度,同时减少板材甲醛的释放。     

热水老化对聚碳酸酯结构和性能的影响

利用拉伸试验、傅里叶变换红外光谱(FTIR)、差示扫描量热法(DSC)和扫描电子显微镜(SEM),分析了PC在80℃水浴中人工老化800 h过程中的老化行为。结果表明,在热条件下,水有利于PC的水解,在热、水环境中,PC老化主要由水解引起;DSC分析显示,过渡区有两个明显的吸热峰,随着老化的进程,FTIR吸收峰变化;SEM及力学测试都表明,PC在热水老化后脆性提高。     

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.     

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.……     

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...     

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.     

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.     

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 ...