不同热压方法对无胶烟秆碎料板力学性能的影响

分别采用普通热压和喷蒸热压2种热压方法制备了无胶烟秆碎料板,对它们的物理力学性能进行了对比研究与分析。结果发现,与普通热压法相比,喷蒸热压法制备的无胶烟秆碎料板的静曲强度、弹性模量与内结合强度明显提高,吸水厚度膨胀率显著减小,其原因可能是不同热压过程中烟秆碎料发生了化学变化。     

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℃。     

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。     

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。     

无胶竹碎料板喷蒸热压成型机理

以竹碎料为原料,通过喷蒸热压工艺制备无胶竹碎料板。采用傅里叶红外光谱分析(FT-IR)、固体核磁共振波谱分析(CP/MAS13C NMR)、高效液相色谱分析(HPLC)以及比表面积分析(BET)等分析手段分析了无胶竹碎料板成型机理。结果表明,喷蒸热压过程的水、热协同作用使纤维素分子的活性羟基数量增加,活性羟基间可以形成氢键(O—H…H),在竹碎料间可以形成范德华力;喷蒸热压过程的水、热协同作用使竹碎料中的部分半纤维素产生水解,水解产物可以进行缩聚反应,生成类似于胶粘剂的缩聚呋喃树脂,也可以直接与具有酚羟基结构的木素发生缩聚反应,形成类似于酚醛树脂胶粘剂的缩合物。另外,竹碎料中的木质素受水热作用被充分流展并部分均匀分布在碎料颗粒间,一定程度上也改善了无胶板物理力学性能。     

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。     

废旧利乐包 / 木屑复合板热压优化工艺研究

为提高废旧利乐包的再利用效率,扩大其在包装领域的应用范围,研究了废旧利乐包/木屑复合板制备的热压优化工艺。采用正交试验法,以施胶量、热压温度、热压时间、利乐包与木屑质量比为影响因素,分别以静曲强度、弹性模量和2 h吸水厚度膨胀率为检测指标,得到了此种复合板热压优化工艺参数。结果表明板材热压优化工艺参数为:施胶量14%,热压温度150℃,热压时间420 s,利乐包与木屑质比比4∶6,在此条件下,板材最大静曲强度为23.1 MPa,最大弹性模量为2917 MPa,2 h吸水厚度膨胀率最小,为6.1%。     

麦秸/木材复合无机碎料板的性能对比研究

以麦秸、木材和环保阻燃的镁系无机胶粘剂为主要原料,通过麦秸与木材均匀混合以及麦秸、木材分层复合两种方式,采用热压工艺分别制备均质结构板、以木材为表层、麦秸为芯层的3层结构板-1和以麦秸为表层、木材为芯层的3层结构板-2,对比分析了3种板材的物理力学性能和阻燃性能。结果表明,3层结构板-2的静曲强度(MOR)、弹性模量(MOE)高于其它两种板材,内结合强度(IB)小于均质结构板,2h吸水厚度膨胀率(TS)大于均质结构板,增加麦秸与木材配比可以提高3层结构板-2的内结合强度;与其他两种板材相比,3层结构板-2的热释放速率(HRR)、总热释放量(THR)较小,点燃时间较长,阻燃性能较好,增加麦秸与木材配比,可以提高板材阻燃性能;较优的板坯结构为以麦秸为表层、木材为芯层的3层结构板,适当增加麦秸与木材配比可以提高3层结构板的综合性能。     

棉杆碎料热压代木包装板材的工艺参数研究

棉杆是代木包装制品加工的较好原材料之一。运用正交试验方法,研究了以淀粉为主要胶黏剂热压生产棉杆碎料板材的工艺参数。对于一定尺寸的试样来说,热压成型的最佳工艺参数为:热压温度140℃,热压时间20min,采用不加助剂的淀粉胶黏剂,棉杆用料量为75g,板材密度约为0.7g/cm3。     

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。     

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.     

Effect of Permeable Crystalline Material on Steel Reinforcement Corrosion of Concrete

Permeable crystalline materialcan permeate into pores and cracks of concrete and catalyze the reaction between Ca(OH) 2and unhydrated cement to generate a great quantity needle non-soluble crystals, which can stop up the pores and cracks of concrete, and increase the impermeability of concrete. This paper reported the results of a study conducted to evaluate steel reinforcement corrosion of concrete specimens uncoated and coated with permeable crystalline material as well as mixed with the permeable crystalline material. The properties evaluated for corrosion test were water impermeability, water absorption, compressive strength and potential. The results of water impermeability, water absorption, compressive strength clearly showed that the permeable crystalline material could prohibit water, any soluble salts and moisture from penetrating the concrete to cause corrosion, leaking, and other problems, and it did increase the compressive strength, which was favorable for protection of corrosion of reinforcing steel. Moreover, it was concluded from the potential-time curve that the steel reinforcement of uncoated specimen was in the state of activation whereas that of other specimens coated and mixed with the permeable crystalline material was in the state of inactivation. Above all, it was indicated that the permeable crystalline materialis very effective to protect the steel reinforcement of concrete from corrosion.     

The Research and Application About "Dry Peeling Off" Technology for Airplane Surface Paint Layer

In this paper, the principle of spurting take off lacquer were introduced; and with orthogonal method the unsaturate polyester was prepared ;it was easy to peel airplane paint layer off with this material and equipment.     

Quality Study of Honeycomb Core Shaping Without Wax Stabilization

Sandwich panels utilizing honeycomb cores result in lightweight, high-strength units that are very rigid. Indeed, they give honeycomb panels the best strength-to-weight ratio of any construction type available. Conventionally, the wax is poured into the cell of the core to strengthen the structure and prevent the core from being crushed during milling. Much time and labor is required to wax, mill, and clean the cores. In this study, the process of pouring wax into the core was skipped. In other words, the cutter directly milled the core. Experiments showed that the compressive strength of the core produced without wax stabilization was only 3% lower than that of cores produced using the traditional method. In addition, the drum peel strengths of cores produced without wax stabilization were 38.4% higher than cores produced using the traditional method, in which residual wax seriously polluted the adhesive. It was also found that eliminating the wax process can reduce costs.     

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.     

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.     

In-process thermal treatment of polylactic acid in fused deposition modelling

Polylactic acid (PLA) is one of the most widely used open source fused filament fabrication materials due to its ease of extrusion, biodegradability, and mechanical strength. The mechanical strength of PLA largely depends on the proper growth of its semi-crystalline structure, which can be severely impaired by a low rate of crystallization, particularly in open source printers. This can be further aggravated by the non-uniform thermal distribution of heat that causes improper curing among the extruded beads of the printing material. As a result, PLA printed on open source printers does not achieve the best mechanical properties. This research, for the first time, proposes an additive-free solution implemented through a detailed set of experimentation to improve the curing rate through in-process temperature variations to cure the joints among the beads. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy is used to confirm the improvements in the bead joints. This work is conducted in two phases of experiments. In the first phase, a full factorial ANOVA is used to investigate various process parameters and the important variables are used in the second phase to print test specimens in four different sets.     

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.     

Early ironwork in Biscay: Survey,excavation, experimentation and materials characterization. An integral study of the mountainside ironworks (ferrerías de monte or “haizeolak”)

ABSTRACT

The production of iron in Biscay (Basque Country, Spain) has been a hallmark of this territory of the North of the Iberian Peninsula throughout its history. The Archaeology team of the Basque Country Mining Museum has spent 13 years, so far, studying the origins of this activity through the evidences left at the old pre-hydraulic iron production workshops known as mountainside ironworks (ferrerías de monte) or haizeolak. It has catalogued 170 archaeometallurgical sites of this type in Biscay, and the archeological excavation of some of them has led to the knowledge of the different stages of the production process that took place in these workshops. The team has also experimentally reproduced the work carried out in a mountainside ironworks from the High Middle Ages, and it has currently started the characterization process of this type of activity through the study of the collected materials.