共查询到20条相似文献,搜索用时 62 毫秒
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纸板是瓦楞纸箱、纸盒等产品生产的主要原材料,它的性能如何直接或间接影响了产品的内在质量和使用效果。对瓦楞纸箱、纸盒等包装产品来说,具有耐磨、防水和防潮性能,并且具有较高的强度和较好的气密性,是纸板使用特性的基本质量要求。但是,纸厂生产出来的普通纸板,往往是不具备良好的耐磨性、防水性和防潮性能等。 相似文献
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采用气压式毛细管流变仪对聚丙烯腈/二甲基乙酰胺/聚乙烯吡咯烷酮(PAN/DMAc/PVP)中空纤维铸膜液的流变性能进行了研究.实验结果表明,该铸膜液属假塑型流体.物料性质,如PAN分子量、PAN质量分数、添加剂质量分数会影响体系的流动性能.PAN分子量为Mη=13.1×104、PAN质量分数为14%、添加剂PVP质量分数为10%时,该铸膜液的流动性最好.另外,温度对体系的流动性也有影响.对特定的PAN铸膜体系来说,升高温度使体系的黏度降低,流动性变好;而当体系中PAN分子量增大、PAN质量分数增加时,体系的黏度增大,活化能变大,因而对温度的敏感性也增强. 相似文献
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通过对聚乙烯的特性黏度、凝胶含量、羧基含量和红外光谱特征吸收的测定,研究了PEG400含量为8%(质量分数,下同),5%,1%,0.1%,0%的五种聚乙烯膜样品在人工加速老化实验下的光氧化降解特性,并利用扫描电镜对PEG400含量为1%的聚乙烯膜进行了表面形貌分析.结果表明:在实验条件下,PEG400明显加速了聚乙烯膜中的自由基反应,致使聚乙烯分子交联和断链,并在聚乙烯分子链中引入了羰基和羧基;当PEG400含量为1%时,聚乙烯膜的降解效果最为明显,光照60d后基体聚乙烯的特性黏度由67.6 Pa·s下降为34.9 Pa·s,凝胶含量为5.84%,羧基含量为1.29%. 相似文献
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高强度冷冻防潮瓦楞纸箱研制 总被引:1,自引:1,他引:0
目的利用新型经纬线纸研制高强度冷冻防潮瓦楞纸箱,以适应冷链食品低温贮藏、运输的物流环境。方法实验测试经纬线纸包装特性,确定其适合瓦楞纸板的组分;应用Ansys分析软件,建立经纬线瓦楞纸箱和普通瓦楞纸箱的有限元模型,模拟实际流通环境对纸箱模型施加载荷,求出2种瓦楞纸箱的抗压强度;进行空箱抗压实验,比较2种方法下经纬线纸箱与普通纸箱的抗压强度大小。结果用预应力经纬线纸作为瓦楞纸箱的面纸,在低温流通环境中其空箱抗压强度比相同芯纸和里纸的普通瓦楞纸箱高约30%,并且经纬线纸纸箱的质量比普通瓦楞纸箱的质量低12%。结论在实际生产中,可以利用经纬线纸制造高强度的低温防潮箱,以适应冷链流通环境,也可以制作低克重高强度纸箱,以节约纸箱用纸量。 相似文献
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目的评价环境相对湿度对瓦楞纸箱质量的影响。方法在23℃和相对湿度为50%,70%,98%的环境中,比较3层、5层和7层瓦楞纸箱的抗压强度、耐破强度以及吸湿率等性能指标。结果瓦楞纸箱的吸湿率和含水率随环境湿度的升高而增大;当环境相对湿度在50%~70%时,瓦楞纸箱的耐破强度、边压强度及抗压强度等性能保持稳定;当环境相对湿度达到98%时,3层、5层和7层瓦楞纸箱的耐破强度比相对湿度50%条件下分别降低了53.8%,74.1%和76.3%,边压强度分别降低了71.4%,70.3%和77.5%,抗压强度和堆码层数显著下降;7层瓦楞纸箱的防潮耐压能力优于3层和5层。结论高湿度会引起瓦楞纸箱的性能指标显著降低,功能受损。 相似文献
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冷冻水产瓦楞纸箱是由一张瓦楞纸板模切折叠而成,纸板面纸为复合纸,由超薄压光牛皮纸、薄膜形态的聚乙烯PE、国产牛皮纸复合而成,纸板里纸表面涂布防水涂料,部分防水涂料被压入里纸浅表层,形成新的物质层,使涂料与里纸浅表层紧密结合在一起。本产品防水、防潮性能优异,印刷效果好,经济效益高,可广泛应用于自动包装线上机械开箱、装箱、打包等。 相似文献
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《International journal for numerical methods in engineering》2018,113(9):1488-1506
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. 相似文献
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Steffen Müller-Probandt 《材料科学与工程:中英文B版...》2018,(4):161-177
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... 相似文献
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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. 相似文献
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Janet Lang 《Materials and Manufacturing Processes》2017,32(7-8):857-866
ABSTRACTThe 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. 相似文献
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Standards are the basis for production enterprises to organize production ex-factory inspection trade 《中国标准化(英文版)》2008,25(1):24-25
Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.…… 相似文献
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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. 相似文献
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S. K. Malhotra Paramanand Singh A. Thirunavukkarasu 《Materials and Manufacturing Processes》2006,21(7):652-657
Al2O3-ZrO2 nanocomposites were developed starting with the solgel process. Composite alumina-zirconia nanopowders were synthesized from metallorganic precursors (Aluminium secondary butoxide and zirconium Iso propoxide) using the solgel process. The parameters affecting the synthesis—solvent, concentration of precursor, R/H ratio (i.e., dilution of water in solvent)—were varied as also the temperature and pH. BET and TEM were used to measure nanosize. Diffuse reflectance spectroscopy and also qualitative optical absorption led to identical particle size estimate. The variation of process parameters was used to study the effect and interdependence of process parameters. Artificial Neural Networks was used to rigorously analyze the process. Although this led to confirmation of interdependence of parameters, the presence of a single overwhelming solvent variable was also established. Then the optimal process was used to synthesize more nanopowder. To produce bulk nanocomposite the nanopowders were sintered by varying the temperature and time period. The sintered lithoids were probed with a vickers hardness tester to measure elastic modulus, hardness, and fracture toughness. The results showed high elastic modulus, modest hardness, and very high fracture toughness. 相似文献
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The end of over unit products of more than Chinese firms have passed the quality grade certification for liquor products. These products involve distilled spirits beer wine yellow wine fruit syrup wine others cover over % of the national top-branded liquor products.…… 《中国标准化(英文版)》2008,25(1):30
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.…… 相似文献
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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. 相似文献