Effect of LiTFSI and LiFSI on Cycling Performance of Lithium Metal Batteries Using Thermoplastic Polyurethane/Halloysite Nanotubes Solid Electrolyte

All-solid-state lithium batteries(ASSLB) are promising candidates for next-generation energy storage devices.Nevertheless,the large-scale commercial application of high energy density AS S LB with the polymer electrolyte still faces challenges.In this study,a thin solid polymer composite electrolyte(SPCE) is prepared through a facile and cost-effective strategy with an infiltration of thermoplastic polyurethane(TPU),lithium salt(LiTFSI or LiFSI),and halloysite nanotubes(HNTs) in a porous framework of polyethylene separator(PE)(TPU-HNTs-LiTFSI-PE or TPU-HNTs-LiFSI-PE).The composition,electrochemical performance,and especially the effect of anions(TFSI~-and FSI~-) on cycling performance are investigated.The results reveal that the flexible TPU-HNTs-LiTFSI-PE and TPU-HNTs-LiFSI-PE with a thickness of 34 μm exhibit wide electrochemical windows of 4.9 and 5.1 V(vs.Li+/Li) at 60℃,respectively.Reduction in FSI~-tends to form more LiF and sulfur compounds at the interface between TPU-HNTs-LiFSI-PE and Li metal anode,thus enhancing the interfacial stability.As a result,cell composed of TPU-HNTs-LiFSI-PE exhibits a smaller increase in interfacial resistance of solid electrolyte interphase(SEI) with a distinct decrease in charge-transfer resistance during cycling.Li|Li symmetric cell with TPU-HNTs-LiFSI-PE could keep its stable overpotential profile for nearly 1300 h with a low hysteresis of approximately39 mV at a current density of 0.1 mA cm~(-2),while a sudden voltage rise with internal cell impedance-surge signals was observed within 600 h for cell composed of TPU-HNTs-LiTFSI-PE.The initial capacities of NCMITPU-HNTs-LiTFSIPEILi and NCMITPU-HNTs-LiFSI-PEILi cells were 149 and 114 mAh g~(-1),with capacity retention rates of 83.52% and89.99% after 300 cycles at 0.5 C,respectively.This study provides a valuable guideline for designing flexible SPCE,which shows great application prospect in the practice of ASSLB.     

2018～2019年世界塑料工业进展(Ⅱ)

收集了2018年7月~2019年6月世界工程塑料和特种工程塑料工业的相关资料,介绍了2018~2019年世界工程塑料和特种工程塑料工业的发展情况,按工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯)和特种工程塑料(聚苯硫醚、液晶聚合物、聚醚醚酮、聚芳砜、聚邻苯二甲酰胺)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍。     

MgO as a non-pyrolyzable pore former in porous membrane supports

The gas permeability of Y_0.03Zr_0.97O₂ (3Y-TZP) porous supports from thermoplastic feedstocks has been improved by adding MgO as a non-pyrolyzable pore former. Common pyrolyzable pore formers such as graphite often produce tortuous and narrow pore channels with low gas permeability, limiting the performance of oxygen transport membranes or other membranes relying on gas transport to the active membrane surface. Thermoplastic feedstocks for extrusion of tubular 3Y-TZP supports were prepared with four different amounts of pyrolyzable pore formers and/or MgO as non-pyrolyzable pore former. The MgO was removed after sintering by leaching in acetic acid. With this technique we obtained porosities above 70 vol% and gas permeabilities above 3?10^?14?m². Compared to samples with only pyrolyzable pore formers, the non-pyrolyzable pore former increases the gas permeability and reduces the tortuosity.     

Amide-containing segmented copolymers

This review highlights the synthesis, physical properties, and emerging technologies of state-of-the-art segmented copolymers containing amide hydrogen bonding sites. Amide hydrogen bonding plays a crucial role in the physical properties associated with amide-containing segmented copolymers. Amide hard segments are accessible in many different forms from amorphous alkyl amides to crystalline aramids and greatly influence copolymer morphology and mechanical properties. Variations in copolymer structure allow for the fine tuning of physical properties and the ability to predict mechanical performance based upon structural modifications. This review includes various synthetic methods for producing well-defined amide-containing segmented copolymers as well as common applications. Also, the morphological and mechanical properties associated with modifications in copolymer structure are discussed.     

Monomer casting nylon-6-b-polyether amine copolymers: Synthesis and properties

MC nylon-6-b-polyether amine copolymers were prepared with macro-initiator based on amino-terminated polyether amine functionalized with isocyanate via in-situ polymerization. It was found that the introduction of polyether amine delayed the polymerization process of caprolactam by increasing apparent activation energy and pre-exponential factor, resulting in the decrease of molecular weight of nylon-6. The motion of molecular chain of the copolymers was easy because of the decreased hydrogen bonds and weakened inter-molecular forces. The physical entanglement of molecular chains of the copolymers was significant and strong which increased the entanglement density. Only the nylon-6 phase crystallized in the copolymers and the crystal grain size, spherulite size and crystallinity of the copolymers decreased. A small amount of γ crystal formed at high polyether amine content. The copolymers presented obvious strain hardening behavior in stress-strain curves and the loss factor dramatically increased while the glass transition temperature and storage module decreased. The fracture surface of the copolymers became rough and presented hairy structure, indicating that the toughening mechanism of the copolymers corresponded to the multi-layer crack extension mechanism.     

Miscibility analysis,viscoelastic properties and morphology of cyclic olefin copolymer/polyolefin elastomer (COC/POE) blends

Miscibility of cyclic olefin copolymer/polyolefin elastomer (COC/POE) blends over full composition range was investigated through determination of viscoelastic characteristics both at melt and solid state as well as by direct morphological analysis using experimental and theoretical approaches. The melt viscosity, storage modulus and Han diagrams were used for analyzing the rheological behavior. It was found that the storage modulus of neat COC was higher than that of neat POE, while the modulus of the blends were in between the modulus of the neat components. Palierne and Gramspacher–Meinssner models were used in order to predict the storage and loss moduli of COC and POE. Better correspondence of Palierne model with the experimental results was observed as compared to the other model. Contrary to the Veenstra model, the calculated modulus via Coran model was reasonably in good agreement with the experimental results for blends with co-continuous morphology. Dynamic mechanical investigations have revealed that COC/POE blends were immiscible which firmly supported the morphological and rheological findings.     

Textile applications of commercial photochromic dyes: part8. A statistical investigation of the influence of photochromic dyes on thermoplastic fibres using a UV-irradiation technique

Abstract

This research investigates the influence of the commercial photochromic dye concentration, expressed as a percentage, and polymer type and their interaction on the photocoloration properties of the as-spun and drawn fibres regarding the melt-spinning process. As-spun fibres made of polypropylene, polyethylene and polyester were spun with different percentages of the photochromic dye, drawn, tested and analysed under a factorial experimental design using appropriate experimental and statistical methods. According to the analyses and by using an independent source of ultraviolet irradiation and traditional colour measurement instrumentation of the degree of photocoloration and background colour, the most effective and significant parameter influencing the as-spun fibre’s photocoloration properties are the polymer type; the dye percentage effect was noted in the degree of photocoloration. The effects of the multi-stage hot-drawing process on the photocoloration properties of the drawn polypropylene and polyethylene fibres were characterised and statistically modelled. The dyed fibres showed reversible photochromism, developing pronounced colours from weak background colours on irradiation with ultraviolet light and returning to their original state when the ultraviolet light source was removed. The dye percentage positively affects the photocoloration of the as-spun and drawn polypropylene and polyethylene fibres. A new forecasting data source was achieved to optimise the selection of the polymer and the dye percentage and to specify the direction of increasing or decreasing of the significant process parameters. Utilising the elastic properties of manufactured fibres, they could be used in the development of chromic textiles for creative design, functional or smart purposes.     

Interfacial crystallization and its mechanism in in-situ dynamically vulcanized iPP/POE blends

The effect of in-situ crosslinking of poly (ethylene-co-octene) (POE) rubber phase on the interfacial crystallization of isotactic polypropylene (iPP) in dynamically vulcanized iPP/POE blends was studied. The results showed that in situ crosslinking of POE obviously increased the interfacial crystallization of iPP in the dynamically vulcanized blends, comparing with that of pure iPP and the unvulcanized blend. The interfacial crystallization of iPP was further increased with the increase in crosslink degree. After annealing, the obvious interfacial crystallization was still obtained in the blend with high crosslink degree. Based on the fluctuation assisted nucleation mechanism in solution blended iPP/polyolefin block copolymer (OBC) blends, we proposed for the first time the interfacial crystallization mechanism in dynamically vulcanized blends: the oriented chains of iPP formed by concentration fluctuation at the interface during phase separation or shearing stress during melt mixing can be maintained because of the in situ crosslinking of POE phase, resulting in the enhancement of nucleation density at the iPP/POE interface. Our study proposes a new interfacial crystallization mechanism, and provides guidance for the preparation of high performance thermoplastic vulcanizates (TPVs) product by tailoring the interfacial crystallization of TPVs.     

a-ODPA共聚的耐高温热塑性聚酰亚胺的研究

以2,3,3',4'-二苯醚四甲酸二酐(a-ODPA)为单体,与不同配比的4,4'-二氨基二苯醚(4,4'-ODA)和1,4-苯二胺(1,4-PDA)共聚,制备了一系列的聚酰亚胺(PI)。结果表明,随着1,4-PDA摩尔分数的增加,Tg(玻璃化转变温度)从279℃逐渐上升到328℃,同时比浓对数黏度从110 mL/g逐渐下降到40 mL/g(DMAc,25℃)。当1,4-PDA的摩尔分数不超过0.4的时候,该PI在DMAc、DMF、NMP、DMSO和γ-丁内酯中具有良好的溶解性,塑料样条在220℃的高温下,力学性能的保持率良好。     

超临界二氧化碳发泡EPDM/LDPE热塑性弹性体微孔泡沫

本文通过熔融共混制得了EPDM/LDPE热塑性弹性体,压制标准试样,然后使用超临界二氧化碳作为发泡剂在高压反应釜中进行物理发泡。通过万能拉力机测试了弹性体力学性能,用扫描电镜观察了拉伸断面和泡孔的微观结构。结果表明：DCP硫化体系的热塑性弹性体的综合力学性能要优于硫黄硫化体系,随着硫化剂用量的增多,拉伸强度和撕裂强度有一个最大值,硬度上升;橡塑比在4:6时,力学性能达到最佳,最大拉伸强度为7.5MPa,最大撕裂强度为27.6MPa。扫描电镜观察其拉伸断面形貌,表明EPDM橡胶相与LDPE塑料相呈现“海-岛”两相微观结构;泡孔大小均匀性较好,成功制备了微米级微孔泡沫且泡孔大小分布均匀。