Moulded pulp products manufacturing with thermoforming

For an effective optimization of pulp thermoforming and of the moulded pulp products manufactured by this process, a full understanding of the process physics combined with full knowledge of the pressing equipment is necessary. For this reason, in this Addendum, we clarify how the process parameters “Holding time,” “Vacuum time,” “Cycle time,” and “Temperature” were interpreted and subsequently defined for the analysis of the process and product‐related outputs of the thermoforming experiments.     

Moulded Pulp Manufacturing: Overview and Prospects for the Process Technology

Eco‐friendly packaging such as moulded pulp products have gained commercial importance in the recent years. However, it remains a greatly under‐researched area, and there is an arising need to consolidate the best practices from research and industry in order to increase its implementation. The goal of this paper is to give an overview of the main aspects involved in the manufacture of moulded pulp products. This includes a classification of moulded pulp products, historical and current applications, production processes, materials, mechanical properties and environmental sustainability. Moreover, based on the latest research in the field, an innovative drying technique that utilizes concepts derived from impulse drying is presented, and the implementation of this process technology is discussed. Copyright © 2017 John Wiley & Sons, Ltd.     

纸浆模塑制品的研究进展

对纸浆模塑制品的发展现状及其性能研究的进展作了详细的综述,并提出对纸浆模塑制品的研究,应着重在材料特性参数即材料的弹性模量、泊松比、剪切模量与材料的紧度、温度和湿度的函数规律及单元结构和整体结构在静载及动载下的基本力学性能方面,形成纸浆模塑制品的理论设计方法,较好地解决其设计周期长和模具成本高的问题.     

Characterization of moulded‐fibre packaging with respect to water vapour sorption and permeation at different combinations of internal and external humidity

A moulded‐fibre packaging system was characterized under conditions simulating real‐life packaging of food. A steady‐state moisture flux through the moulded‐fibre packaging was generated by subjecting the system to different combinations of internal humidity [33–97% r.h. (0.33–0.97a_w of contents), RH(i)] and surrounding humidity [33–97% r.h., RH(e)]. The objective was to resolve whether a hygroscopic fibre material absorbs moisture proportional to the rate of moisture transport, and the moulded‐fibre material was thus characterized with respect to accumulation of moisture in the fibre material, water vapour transmission rate (WVTR) and permeability (k/x). These steady‐state properties showed significant asymmetry depending on direction of moisture transport. When moisture was transported out of the system [RH(i) > RH(e)] the fibre material adsorbed moisture to a considerable lesser extent compared to when moisture was transported into the system [RH(i) < RH(e)], just as (k/x) increased by 15–20%. Taking both directions of moisture transport into account, the moisture content of the fibre material depended largely on surrounding humidity, even at high internal humidity. Moisture contents ranged from 5.5 g/100 g dry fibre at RH(e) 33% r.h. to 16.4–25.1 g/100 g dry fibre at RH(e) 97% r.h. The observed asymmetry was shown to derive from the experimental set‐up and not from the material itself. A minimal theory based on the various transport steps in the experimental set‐up was proposed in order to qualitatively explain this asymmetry. The rate of moisture adsorption in moulded‐fibre was described by the normalized response function H(t). Response times to reach equilibrium moisture contents were 6 and 8 h for RH(e) 33 and 53% r.h., and 40 and 41 h for RH(e) 75 and 97% r.h. Copyright © 2004 John Wiley & Sons, Ltd.     

纸浆模塑缓冲包装六步设计法

介绍了纸浆模塑的缓冲机理不同于一般缓冲包装材料,其缓冲结构设计也不采用基于缓冲系数的六步法。在分析纸浆模塑缓冲机理及设计要求基础上,对国内纸模结构要素设计及经验数据进行了分析探讨,并基于经验类比法和有限元法提出了纸浆模塑缓冲托的六步设计法。     

三维多孔结构聚苯胺/石墨烯复合材料的制备及电化学性能

以自制聚苯胺水凝胶和氧化石墨烯为原料采用原位聚合法和溶液灌注法制备三维多孔结构的聚苯胺/氧化石墨烯复合材料,然后在氢碘酸的还原下制备聚苯胺/石墨烯复合材料。采用红外光谱法、场发射扫描电子显微镜和热重分析法对制备的复合材料的结构、形貌和组成进行表征,并采用三电极测试方式对其电化学性能进行测试。结果表明,氧化石墨烯的掺入能有效防止聚苯胺和氧化石墨烯的团聚和堆叠问题,获得了具有良好三维多孔结构的聚苯胺/氧化石墨烯复合物;聚苯胺/氧化石墨烯复合材料被氢碘酸还原后,得到的聚苯胺/石墨烯复合材料的热稳定性有所降低,但其比电容和导电性等有了很大的提高,在电流密度为0.5 A/g时,PANI/GO和PANI/r GO的比电容分别为240.38 F/g和321.91F/g。     

Edge‐Terminated MoS2 Nanoassembled Electrocatalyst via In Situ Hybridization with 3D Carbon Network

Transition metal dichalcogenides, especially MoS₂, are considered as promising electrocatalysts for hydrogen evolution reaction (HER). Since the physicochemical properties of MoS₂ and electrode morphology are highly sensitive factor for HER performance, designed synthesis is highly pursued. Here, an in situ method to prepare a 3D carbon/MoS₂ hybrid catalyst, motivated by the graphene ribbon synthesis process, is reported. By rational design strategies, the hybrid electrocatalysts with cross‐connected porous structure are obtained, and they show a high HER activity even comparable to the state‐of‐the‐art MoS₂ catalyst without appreciable activity loss in long‐term operations. Based on various physicochemical techniques, it is demonstrated that the synthetic procedure can effectively guide the formation of active site and 3D structure with a distinctive feature; increased exposure of active sites by decreased domain size and intrinsically high activity through controlling the number of stacking layers. Moreover, the importance of structural properties of the MoS₂‐based catalysts is verified by controlled experiments, validating the effectiveness of the designed synthesis approach.     

Magnetic orientation of steel fibres in self-compacting concrete beams: Effect on failure behaviour

The magnetic orientation of steel fibres in transparent silicone oil and in fresh, self-compacting concrete (SCC) beams is studied experimentally. The effect of the generated fibre locations and orientations on the failure response of the SCC beams is determined by means of three-point bend tests. A relatively small coil was designed for the magnetic orientation of single and multiple fibres in the transparent silicone oil. The time required for orienting a single fibre was measured for a range of magnetic fluxes, which showed to strongly decrease with increasing magnetic field strength. The presence of gravel on the fibre orientation behaviour was considered in order to mimic the influence by a concrete aggregate, indicating that the gravel does not prevent rotations and chain formations of fibres. A larger coil was developed for the magnetic orientation of fibres in freshly casted SCC beams. The energy absorption capacity of SCC beams subjected to three-point bending scales approximately proportionally with the number of “well-oriented fibres” bridging the catastrophic failure crack, which emphasizes the importance of adequately orienting steel fibres with the magnetic orientation technique.     

From Flatland to Spaceland: Higher Dimensional Patterning with Two‐Dimensional Materials

The creation of three‐dimensional (3D) structures from two‐dimensional (2D) nanomaterial building blocks enables novel chemical, mechanical or physical functionalities that cannot be realized with planar thin films or in bulk materials. Here, we review the use of emerging 2D materials to create complex out‐of‐plane surface topographies and 3D material architectures. We focus on recent approaches that yield periodic textures or patterns, and present four techniques as case studies: (i) wrinkling and crumpling of planar sheets, (ii) encapsulation by crumpled nanosheet shells, (iii) origami folding and kirigami cutting to create programmed curvature, and (iv) 3D printing of 2D material suspensions. Work to date in this field has primarily used graphene and graphene oxide as the 2D building blocks, and we consider how these unconventional approaches may be extended to alternative 2D materials and their heterostructures. Taken together, these emerging patterning and texturing techniques represent an intriguing alternative to conventional materials synthesis and processing methods, and are expected to contribute to the development of new composites, stretchable electronics, energy storage devices, chemical barriers, and biomaterials.     

碳纳米管与石墨烯协同改性天然石墨及其电化学性能

以碳纳米管和氧化石墨烯为原料,二者按5∶3混合超声分散再高温还原制备碳纳米管/石墨烯/天然石墨(CNTs/rGO/NG)锂离子复合负极材料。采用扫描电镜(SEM)、X射线衍射(XRD)、红外光谱(FTIR)和电化学测试等分析技术对复合材料的形貌、结构、电化学进行表征。结果表明:石墨烯和碳纳米管在天然石墨表面形成三维立体网络结构。与纯天然石墨相比,CNTs/rGO/NG复合材料具有良好的倍率性能和循环寿命,在0.1C时首次放电比容量为479mAh/g,可逆容量达473mAh/g,循环100次后容量为439.5mAh/g,容量保持率为92%,在0.5,1,5C不同电流倍率时容量依次为457,433,394mAh/g。     

Experimental investigation of 3D sandwich structure with core reinforced by composite columns

3D sandwich structure with foam core reinforced by composite columns, a new concept of sandwich structure, is designed and manufactured. Five types of samples with different densities of composite columns (1, 1.5, 2, 2.5 and 4 columns/cm²) are fabricated, tested and analyzed under bending, out-of-plane compressive and shear loadings. The mechanical properties of compressive, bending and shear increase with increasing of the densities of composite columns. The failure modes were investigated under the optical microscope. The plasticity of the column–core sandwich structure subjected to bending and shear loads can be explained by the mechanism of the inclination and chain-like failure of composite columns.     

Paraffin-based shape-stable phase change materials with graphene/carbon nanotube three-dimensional network structure

A novel kind of paraffin-based shape-stable phase change materials (SSPCMs) was prepared by introducing paraffin into reduced graphene oxide (rGO)/carbon nanotubes (CNTs) aerogel via vacuum-assisted impregnation method. The effects of ratio of rGO to CNTs in 3D network structure on morphology, structure and property of paraffin-based SSPCMs were investigated. The rGO/CNTs 3D network structure with high thermal conductivity, served as thermally conductive skeleton together. In particular, CNTs was used as a secondary heat conductive filler, which could be well dispered in the SSPCMs to conduct heat synergistically. The SSPCMs exhibited high thermal conductivity and excellent shape-stability. And the thermal conductivity of SSPCMs can be regulated by adjusting the ratio of rGO to CNTs in aerogels. These results indicate that 3D rGO/CNTs aerogels have advantages as thermally conductive skeleton, and can endow phase transition materials with stable shape, so as to realize the application of phase change materials in the field of heat dissipation.     

Vorticity field structure associated with the 3D Tollmien-Schlichting waves

Details of the vorticity field structure associated with the 3D Tollmien-Schlichting waves have been examined based upon the recent numerical studies of the subject. First, a single obliquet-s wave has been found to have the velocity component parallel to the wave front playing an overall dominant role, in particular, to create the longitudinal vorticity. The so-called Benney-Lin longitudinal vortices are then demonstrated to be, in fact, a minor consequence compared with the localized longitudinal vorticity field and its periodic pumping. Finally, the formation of the longitudinal vorticity field in the fundamental- and subharmonic-mode interactions is explained. The research reported in this paper has been supported in part by Bundesministerium für Forschung und Technologie and by Deutsche Forschungsgemeinschaft. The major part of the paper has been presented at the Third Asian Congress of Fluid Mechanics, 1–5 September 1986, in Tokyo, as a General Lecture by the senior author, FRH.     

不同预制体结构炭/炭复合材料烧蚀性能

采用电弧驻点烧蚀实验方法, 测试了分别以细编穿刺毡和针刺无纬布整体毡为增强体的2种C/C复合材料的烧蚀率, 并用电子扫描显微镜观察了烧蚀表面形貌。结果表明: C/C复合材料的烧蚀由化学烧蚀和机械剥蚀共同控制, 以机械剥蚀为主; 细编穿刺毡结构C/C复合材料由于Z向纤维束的存在, 加速了材料烧蚀表面粗糙度的变化, 烧蚀率略高于针刺无纬布整体毡结构C/C复合材料; 针刺无纬布整体毡结构C/C复合材料中无纬布层与烧蚀气流垂直, 具有良好的烧蚀性能。      

An Electrosynthesized 3D Porous Molybdenum Sulfide/Graphene Film with Enhanced Electrochemical Performance for Lithium Storage

Molybdenum sulfide/graphene composites are promising anode materials for lithium‐ion batteries (LIBs). In this work, MoS_x/graphene composite film with an ideal 3D porous structure is developed via a facile and straightforward electrochemical route. The MoS_x nanoparticles are uniformly anchored on the graphene nanosheets that are randomly arranged, resulting in MoS_x/graphene composites with well‐developed porous structure. Benefiting from such structure and the synergistic effect from two components, this material shows a high specific capacity over 1200 mA h g^?1, an excellent rate performance, and superior cycling stability. The dominating pseudocapacitive behavior in Li storage contributes to the outstanding rate capacity. Importantly, this kind of novel material can be easily produced as 3D microelectrodes for microscaled LIBs that are highly demanded for autonomous microelectronic systems.     

布绒玩具带有省道的曲面展开算法

 三维布片的平面展开是布绒玩具CAD系统开发中两个最大技术难点之一，根据文献检索，至今还没有具备布绒玩具三维曲面展开功能的商品化软件问世。采用弹簧-质点模型，通过优化算法实现了布绒玩具的三维曲面展开，对优化过程中的几何约束采用图形处理的方法加以解决，取得了预期的展开效果。     

基于有限质点法的三维固体弹塑性问题求解

有限质点法是一种新型的数值方法,可有效求解结构或机构的大变位、大变形及其相互耦合等复杂行为,目前已经应用于无穷小机构、可展结构、接触碰撞、结构倒塌破坏、结构屈曲、索杆结构、平面固体、膜结构的找形及褶皱、结构多尺度、结构精细化等方面的研究,均取得了较好的效果。为形成从平面固体到三维固体及弹塑性等问题的完整研究体系,该文基于有限质点法推导了一种适用于三维固体非线性问题分析的四面体固体元,并将其应用于弹塑性问题的求解。通过自编程序,分别计算静力,动力等经典算例,并将该方法的计算结果和有限元法及试验结果进行了对比。结果表明,该方法能够有效地求解三维固体的弹塑性等静动力问题。     

工业建筑预埋件三维快速装配设计方法

当前工业建筑结构预埋件设计主要采用二维CAD软件,效率较低且容易出错。为此提出基于广义参数化模板的三维预埋件快速装配设计方法。该方法建立包含三维参数化形状结构、安装定位方式和二维投影简图等各种信息的预埋件广义参数化模板;通过构建预埋件参数化模板库,采用基于历史的装配设计技术,实现预埋件的快速安装设计。该文方法已经集成到商品化工业建筑结构三维CAD软件InteRDS中,并在实际工程设计中得到应用。