Investigation of fabrication of gas diffusion substrate for proton exchange membrane fuel cells

The gas diffusion substrate (GDS) is essential in the proton exchange membrane fuel cells. Its fabrication techniques affect the performance significantly and are worthy of investigation. In this study, a manufacturing process of the GDS is proposed to understand the formation process of GDS and promote its structure and performance more pertinently. Different states during the preparation process, raw carbon paper, pre-curing, curing, carbonation, and graphitization, are characterized and measured. Experimental and numerical methods are employed to determine the relationships between microstructure, transport, and mechanical performance variation with the fabricating processes. The results show that its porosity, average pore size, and effective diffusivity decrease first and increase after curing. These parameters after graphitization are lower than that of the carbon paper (CP). The electrical resistivity increases dramatically while pre-curing and decreases gradually after curing, carbonation, and graphitization, and it is much reduced after graphitization. Moreover, mechanical measurement results show that both the picks of tensile strength and flexural modulus occur after curing. Its tensile strength shows little change after graphitization compared to the initial paper's. In contrast, the flexural modulus is improved significantly.     

One-step to prepare high-performance gas diffusion layer (GDL) with three different functional layers for proton exchange membrane fuel cells (PEMFCs)

Gas diffusion layer (GDL) is one of the most important components of fuel cells. In order to improve the fuel cell performance, GDL has developed from single layer to dual layers, and then to multiple layers. However, dual or multi layers in GDL are usually prepared by layer-by-layer methods, which cost too much time, energy, and resources. In this work, we successfully developed a facile one-step method to prepare a GDL with three functional layers by utilizing the different sedimentation rates and filtration rates of short carbon fiber (CF) and carbon nanotube (CNT). The treatment temperature for this GDL is much lower than that of traditional method. The thickness of the GDL can be effectively controlled from as thin as 50 μm to more than 200 μm by simply adjusting the content of CF. The GDL with high flexibility is suitable to develop high performance flexible electronics. The fuel cell with the GDL has the maximum power density 1021 mW cm^?2, which shows 19% improvement comparing to the conventional one. Therefore, this work breaks the traditional concept that GDL for fuel cells only can be prepared by very complex and high-cost procedure.     

从首起铜板纸反倾销案看中国反倾销应对策略

介绍了倾销与反倾销的概念;中国作为WTO的成员国,已经利用WTO的反倾销规则这一手段来保护自己。通过对中国首起铜板纸反倾销案胜诉的介绍,分析了我国企业如何应对国外产品的倾销行为,并提出了应对的措施。     

学术论文摘要编写规范化问题探析

学术论文摘要编写是否规范直接影响到论文质量和文献被引用频率。目前此方面常见问题主要为信息量太少,缺乏独立性和自主性、内容重复、叙述欠客观、不使用第三者、语言不精炼,因此作者和编者都应重视摘要编写,努力提高摘要编写质量。     

An Innovative Design for the Fabrication of Flexible Composite Films from Si3N4 Fiber Paper

A high-temperature-resistant flexible substrate is a critical component of high-performance flexible electronic components. Herein, a method that does not require flowing gas and which is suitable for volume production is presented for the preparation of several-millimeter-long silicon nitride (Si₃N₄) fibers with a cross-sectional dimension of 0.1–1.0 μm. Further, a square sheet of paper with a weight of 0.050 g, side lengths of 105 mm each, and thickness of 15 μm is fabricated using the Si₃N₄ fibers via a conventional laboratory paper-making method. Subsequently, the Si₃N₄ paper is coated with an LaNiO₃ sol using a blade-coating machine, dried at 80 °C for 10 min, and then annealed at 650 °C for 60 min to prepare Si₃N₄ fiber paper/LaNiO₃ composite films to evaluate the feasibility of applying the paper as a substrate for fabricating flexible functional films. The experimental results confirm that the Si₃N₄ fiber paper has excellent high-temperature resistance during annealing in air, and the Si₃N₄ paper/LaNiO₃ composite film presents excellent flexibility and conductivity. Thus, membranous flexible electronic components can be fabricated from Si₃N₄ fiber paper/LaNiO₃ paper by a regular high-temperature annealing process.     

TiO2-SiO2介孔复合材料的合成及其在造纸上的应用

介孔材料作为一种新型的纳米结构材料,近年来已经成为跨学科的国际研究热点之一,综述了近几年介孔TiO2-SiO2复合材料的合成、表征及在造纸上的潜在应用.     

CP-3助剂在嘴棒成型纸中的应用

介绍CP - 3助剂的特性、用法以及在嘴棒纸中的作用。     

含氟乳液纸张表面施胶剂的制备及应用研究

以全氟烷基乙基丙烯酸酯(FEA)、苯乙烯(St)、丙烯酸丁酯(BA)、甲基丙烯酰氧乙基三甲基氯化铵(DAC)为共聚单体,异丙醇为溶剂,偶氮二异丁脒盐酸盐(AIBA)为水溶性引发剂,采用半连续无皂乳液聚合法制备含氟丙烯酸酯无皂乳液。系统研究了该含氟乳液作为表面施胶剂对纸张性能的影响,并通过红外光谱进行了表征,通过接触角和扫描电子显微镜进行了性能测试。结果表明,当m(St)∶m(BA)∶m(FEA)∶m(DAC)=3∶3∶2∶1.2,乳液含氟量达到20%时,纸张的防水防油性较佳,抗张强度提高22.3%,耐折度提高38.2%。     

High‐performance printable paper‐like composites derived from plastic flexible film wastes

Owing to lack of proper recycling methods, plastic flexible film wastes are usually directly discarded or incinerated, which brings about severe environmental pollution. Therefore, converting plastic wastes into value‐added products has received more and more attention in recent years. In this work, paper‐like composites derived from plastic flexible film wastes were prepared via the thermally induced phase separation method by adding polyethylene‐graft‐maleic anhydride (PE‐g‐MAH) as a compatibilizer and fumed silica as an additive. The resulting paper‐like composites were characterized by SEM and infrared spectroscopy. Other properties such as mechanical properties, thermal properties, whiteness, printability and adsorption performance were also tested in detail. It was found that remarkable enhancements in mechanical, thermal and printable properties of the paper‐like composites were obtained when nano‐SiO₂ loading was 2.5–3 wt%. Uniformly distributed holes that can endow good printability by providing space for ink or other functional molecules were observed by using SEM. Furthermore, the CIE whiteness value of the resulting composites can reach 91.6%–96.7% on adding nano‐SiO₂. Additionally, the paper‐like composites integrating nano‐SiO₂ and PE‐g‐MAH exhibited good solid ink affinity and high water or oil adsorption capacity. Thus, according to this research, high‐performance printable paper‐like composites used as major components of multifunctional papers can be prepared based on plastic flexible film wastes. © 2019 Society of Chemical Industry