淀粉基胶黏剂鸡毛纤维板的制备工艺优化

目的优化以可溶性淀粉为胶黏剂、羽毛纤维为基材的板材制备工艺,并研究其性能特征。方法通过正交实验等研究板材含水率、施胶量和热压温度对鸡毛纤维板力学性能的影响,确定其优化制备工艺,并通过傅里叶红外光谱研究其板材成型机理。结果淀粉基胶黏剂鸡毛纤维板的优化制备工艺中施胶量为250 kg/m3,鸡毛纤维板坯含水率为15%,热压温度为150℃。施胶量是最大影响因素,随着施胶量的增加,鸡毛纤维板的内结合强度、静曲强度、弹性模量和24 h吸水厚度膨胀率逐渐增大,当施胶量为260 kg/m3时,纤维板内结合强度、静曲强度、弹性模量和24 h吸水厚度膨胀率分别为0.69 MPa,20.48MPa,2675 MPa和10.23%。淀粉含量越高,纤维板吸水性越强。涂布石蜡后其吸水性能显著降低,由未涂布石蜡时的109.89%降低到54.81%。结论将羽毛制作为轻质纤维板材料具有一定的可行性。     

臭冷杉刨花模压平面托盘的工艺和性能研究

以脲醛树脂胶黏剂处理臭冷杉刨花并压制成平面托盘,对平面托盘的厚度膨胀率、支撑脚内结合强度及板面静曲强度进行了研究。经过实验分析得出托盘最佳生产工艺参数为:施胶量20%,热压温度150℃,热压时间30 min;对应的托盘性能为:吸水厚度膨胀率(2 h)为7.34%,支撑脚内结合强度为0.31 MPa,板面静曲强度为24.12 MPa。     

麦秸/木材均质复合无机碎料板的制备及其性能

以麦秸、木材和环保阻燃无机胶黏剂为主要原料,通过麦秸和木材碎料均匀混合的方式,采用热压工艺制备麦秸/木材均质复合无机碎料板,研究了麦秸与木材的配比、施胶量、热压时间和热压温度对板材性能的影响,并通过X射线衍射仪、扫描电镜分析了其对板材性能的影响机制。结果表明,随着麦秸与木材配比减小,板材静曲强度(MOR)、弹性模量(MOE)和内结合强度(IB)逐渐增大,2h吸水厚度膨胀率(TS)逐渐减小,优选配比为m(麦秸)∶m(木材)=4∶6。随着施胶量的增大,板材的MOR、MOE先增大后减小,IB逐渐增大,TS逐渐减小。施胶量为63%时,板材的MOR、MOE分别达到最大值15.5 MPa、3 110 MPa,此时,IB、TS分别为0.47 MPa、5.5%。随着热压温度的升高和热压时间的延长,板材的MOR、MOE、IB逐渐增大,TS逐渐减小。热压温度和热压时间分别为100℃、30min时,MOR、MOE、IB分别达到最大值(16.8 MPa、3 350 MPa、0.56 MPa),TS达到最小值(3.5%)。优化制板工艺为m(麦秸)∶m(木材)=4∶6,施胶量63%,热压时间30min,热压温度100℃。     

异氰酸酯/脲醛树脂复合胶黏制备高强芦苇刨花板及性能研究

目的 为提升芦苇原料单元胶合性能、提高芦苇资源材料化利用率。方法 文中以异氰酸酯/脲醛树脂复合胶黏剂制备芦苇刨花板,并采用三因素三水平的正交试验,研究施胶量、热压时间和温度对板材静曲强度(MOR)、弹性模量(MOE)、内结合强度(IB)和吸水厚度膨胀率(TS)的影响。结果 研究发现,当异氰酸酯占复合胶黏剂质量的11.6%时,芦苇刨花板的较优热压温度、热压时间、施胶量分别为160 ℃、240 s、12%。以该复合胶黏剂制备的芦苇刨花板的MOR、MOE、IB、2 h TS和24 h TS分别为33.68 MPa、3 292 MPa、1.05 MPa、3.64%和9.45%,满足GB/T 4897—2015中在干燥状态下使用的重载型刨花板(6~13 mm)性能要求。结论 文中的研究拓宽了芦苇资源代替木材在包装材料领域的工业化利用。     

大豆与木片共磨制备无胶纤维板的工艺研究

目的为了解决纤维板中游离甲醛释放的问题,基于大豆与木片共磨技术开展无胶纤维板研究。方法利用一定比例大豆和木片原料共磨并制备无胶纤维板,通过对板坯密度、板坯含水率、预处理时间、热压时间、热压温度等几个变量的研究,分析其对无胶纤维板力学性能的影响。结果在单因素试验范围内,随着密度和板坯含水率的增加,板材物理力学性能均有所提升。方差分析表明,热压温度对板材物理力学性能的影响最大,在最优条件下压制出来的板材静曲强度为10.12MPa、弹性模量为1653.94 MPa、吸水厚度膨胀率为19.7%、内结合强度为0.476 MPa。结论当板材密度为0.8 g/cm3,预处理时间为3 d,热压时间为30 min,热压温度为180℃时,压制出的无胶纤维板综合性能最佳。     

无胶竹碎料板的性能研究

以3种不同形态的竹碎料为原料,不添加合成树脂,在不同热压温度条件下制备无胶竹碎料板,研究其性能特性。结果表明,随着热压温度的升高,3种无胶竹碎料板的内结合强度逐步增强,其中片状竹碎料压制的板材最高;同时,丝状和颗粒状竹碎料压制的板材吸水厚度膨胀率性能明显改善,190℃之前片状竹碎料压制的板材吸水厚度膨胀率性能最好,190℃时丝状和颗粒状竹碎料压制的板材出现严重炭化现象使吸水厚度膨胀率优于片状竹碎料压制的板材;另外,丝状竹碎料压制的板材静曲强度和弹性模量最大。竹碎料板的弯曲破坏模式主要包括下表面拉断、芯层剪切破坏,而拉伸破坏模式主要指中间芯层脆性断裂。     

包装用薄型稻草刨花板的制备工艺研究

从包装减量化设计理念出发,探索了薄型稻草刨花板的制备工艺,为绿色包装设计提供材料支撑。 首先在 2% 的 MDI 施胶量水平下,探索了热压温度、热压时间、酚醛胶施胶量对板材物理力学性能的影响,但在最佳工艺条件下板材的内结合强度和吸水厚度膨胀率都没有达标。 将 MDI 的使用量提高到 3% ,并在热压温度为150 ℃ 、热压时间为 2. 0 min/ mm、酚醛胶施胶量为 14% 、石蜡用量为 1% 的最佳工艺条件下,制备的薄型稻草刨花板的各种性能都达到了标准的要求。     

基于改性大豆蛋白胶粘剂的竹纤维板性能

热压温度、热压时间和板坯含水率是影响纤维板力学性能的重要因素。本文采用二次回归通用旋转组合设计试验方法,研究了热压温度、热压时间和板坯含水率对基于改性大豆蛋白胶粘剂的竹纤维板力学性能的影响规律,获得最佳工艺条件为热压温度167℃,热压时间7．8min,板坯含水率34．2％。在此条件下,竹纤维板的静曲强度达16．5MPa,弹性模量1032．6MPa,抗拉强度10．4MPa,厚度膨胀率31．0％。     

基于老化性能的稻壳/木刨花复合包装箱板的优化工艺

目的 为了提高我国农林剩余物资源的利用率,解决我国绿色包装材料的市场需求,研究外包装箱板材料的制备工艺与组分参数。方法 以稻壳和木质刨花为主要原料,以酚醛树脂和异氰酸酯为胶粘剂,采用热压方法制备外包装箱用复合板;采取WCAMA六循环老化方法对试件进行处理,并对老化处理后的复合板进行内结合强度、静曲强度和弹性模量等力学性能的宏观分析和材料组分变化的微观分析。结果 当表层施胶量质量分数为8%、芯层施胶量质量分数为11%、密度为0.9 g/cm3和防水剂含量为0.6%时,复合板的内结合强度、静曲强度和弹性模量保留率在50%以上,具有良好的耐老化性能。结论 基于老化性能得出的制备工艺及组分参数可对绿色环保、经济性好、可持续发展的稻壳-木刨花外包装箱板材料的开发提供理论与实践支撑。     

无机杨木刨花板制备及性能

以杨木刨花和无机胶黏剂为主要原料,通过冷压成型工艺制备了无机杨木刨花板,研究了不同施胶量和密度对无机杨木刨花板物理力学性能的影响,通过XRD和SEM分析了不同施胶量及密度对无机杨木刨花板性能的影响机制,同时通过锥型量热仪分析了无机杨木刨花板的阻燃抑烟性能。结果表明:一方面,随着施胶量增大,无机杨木刨花板静曲强度(MOR)和弹性模量(MOE)先增大后减小,同时,内结合强度(IB)逐渐增大,24 h吸水厚度膨胀率(TS)逐渐减小。施胶量为57%时MOR和MOE分别达到最大值21.5 MPa和4360 MPa,施胶量为65%时IB达到最大值2.61MPa,24 h TS达到最小值3.36%。随着施胶量增大,燃烧的峰值热释放速率(HRR)降低,HRR到达峰值的时间推迟,总热释放量(THR)和总生烟量(TSP)减少。另一方面,随着密度增大,MOR、MOE均逐渐增大,IB先增大后减小,24 h TS先减小后增大,无机杨木刨花板密度为1.1 g/cm3时IB达到最大值3.54 MPa,24 h TS达到最小值3.99%。      

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.     

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.     

Certification Becomes Important for the I Quality; and Safety Supervision of the Chinese Liquor Sector

The end of 2007, over 200 unit products of more than 80 Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits, beer, wine, yellow wine, fruit syrup wine and others, and cover over 80% of the national top-branded liquor products.……     

Deposition and Coating Properties on CVD Tungsten

Surface characterization and microstructure studies are performed on chemical vapor deposited (CVD) tungsten coating. There is about 2 μm thickness diffusion layer of tungsten in the molybdenum substrate. The thermal shock test shows tungsten coating has good adhesion with molybdenum substrate, but the elements of oxygen and carbon in the tungsten coating have the bad affection to the adhesion. The result of high-temperature diffusion experiment is the diffusion rate from molybdenum substrate to tungsten coating is faster.     

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.……     

Analysis of marine hydrobiont lipid extracts as possible cryoprotective agents

We studied a combined effect of the cryoprotectants both of lipid and carbohydrate origin at the presence of DMSO or without it on cell viability and the RNA synthesis in the embryonic mollusc and echinoderm cell cultures obtained at different developmental stages. Cryoprotective properties of exogenous lipids correlated with their thermotropic behavior. Lipid extracts from marine hydrobiontes, which thermal transitions are characterized by relatively small part of calorimetric thermogram area lying at temperatures above 0 °C (6–18%), were found to possess a considerable cryoprotective activity. The results are discussed in relation to the prediction of the cryoprotective activity of lipid extracts for marine animal cells. In addition, it was found that marine invertebrate cells can be cryopreserved without DMSO at the presence of trehalose and lipid extracts of some marine hydrobiontes.     

Low-Temperature Properties of Silver

Pure silver is used extensively in the preparation of high-temperature superconductor wires, tapes, films, and other configurations in which the silver not only shields the superconducting material from the surrounding materials, but also provides a degree of flexibility and strain relief, as well as stabilization and low-resistance electrical contact. Silver is relatively expensive, but at this stage of superconductor development, its unique combination of properties seems to offer the only reasonable means of achieving usable lengths of conductor. In this role, the low-temperature physical (electrical, thermal, magnetic, optical) and mechanical properties of the silver all become important. Here we present a collection of properties data extracted from the cryogenic literature and, to the extent possible, selected for reliability.