Synthesis and characterization of submicron-sized LiNi1/3Co1/3Mn1/3O2 by a simple self-propagating solid-state metathesis method

Submicron-sized LiNi_1/3Co_1/3Mn_1/3O₂ cathode materials were synthesized using a simple self-propagating solid-state metathesis method with the help of ball milling and the following calcination. A mixture of Li(ac)·2H₂O, Ni(ac)₂·4H₂O, Co(ac)₂·4H₂O, Mn(ac)₂·4H₂O (ac = acetate) and excess H₂C₂O₄·2H₂O was used as starting material without any solvent. XRD analyses indicate that the LiNi_1/3Co_1/3Mn_1/3O₂ materials were formed with typical hexagonal structure. The FESEM images show that the primary particle size of the LiNi_1/3Co_1/3Mn_1/3O₂ materials gradually increases from about 100 nm at 700 °C to 200–500 nm at 950 °C with increasing calcination temperature. Among the synthesized materials, the LiNi_1/3Co_1/3Mn_1/3O₂ material calcined at 900 °C exhibits excellent electrochemical performance. The steady discharge capacities of the material cycled at 1 C (160 mA g⁻¹) rate are at about 140 mAh g⁻¹ after 100 cycles in the voltage range 3–4.5 V (versus Li⁺/Li) and the capacity retention is about 87% at the 350th cycle.     

Processing and properties of an ethylene–vinyl acetate blend foam incorporating ethylene–vinyl acetate and polyurethane waste foams

Waste polyurethane foam (w‐PU) and waste ethylene–vinyl acetate foam (w‐EVA) were used as fillers for the production of an ethylene–vinyl acetate (EVA) blend foam. Two different foaming techniques (single‐stage and heat–chill processes) were used for this purpose. The waste foam concentration was varied up to 30 wt % of the original EVA. The physical, mechanical, and morphological properties of the filled foam were studied. The single‐stage process produced blend foams with a lower density and a greater cell size than the foams obtained by the heat–chill process. The density and compression strength of the blend foam increased as the percentage of w‐PU foam increased. However, for the w‐EVA/EVA blend foams, the addition of w‐EVA foam did not significantly affect the density or compression strength compared to the original EVA foams. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44708.     

Facile preparation of magnetic chitosan modified with thiosemicarbazide for adsorption of copper ions from aqueous solution

In this study, magnetic chitosan modified with thiosemicarbazide (TSC‐Fe₃O₄/CTS) was facilely synthesized with glutaraldehyde as the crosslinker, and its application for removal of Cu(II) ions was investigated. The as‐prepared TSC‐Fe₃O₄/CTS was characterized by Fourier transform infrared spectroscopy (FTIR), X‐ray powder diffraction (XRD), and scanning electron microscopy (SEM). The results showed that TSC‐Fe₃O₄/CTS has high adsorption capacity and selectivity towards Cu(II) ions. Adsorption experiments were carried out with different parameters such as pH, solution temperature, contact time and initial concentration of Cu(II) ions. The adsorption process was better described by the pseudo‐second‐order model. The sorption equilibrium data was fitted well with the Langmuir isotherm model and the maximum adsorption capacity toward Cu(II) ions was 256.62 mg/g. The thermodynamic parameters indicated that the adsorption process of Cu(II) ions was exothermic spontaneous reaction. Moreover, this adsorbent showed excellent reusability and the adsorption property remained stable after five cycles. This adsorbent is believed to be one of the promising and favorable adsorbent for the removal of Cu(II) ions from aqueous solution. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44528.     

不同球磨粉碎工艺对固相合成β-磷酸三钙纯度和粒度的影响

采用纳米球磨-超声搅拌工艺制备了β-磷酸三钙粉体,并与传统固相合成工艺进行了对比研究。采用差示扫描量热（DSC）、X射线衍射（XRD）、红外（FTIR）、纳米粒度测试、扫描电镜（SEM）、透射电镜（TEM）及X射线荧光光谱（XRF）等手段对两种工艺所制备粉体进行了纯度和粒度表征。结果表明：相比传统工艺,经过纳米球磨-超声搅拌工艺制备出的β-TCP粉体纯度可达97%以上,平均粒径为666 nm。粉体的纯度高、粒径分布更均匀。同时,纳米球磨加工后的原料平均粒度更小,分散性更好。该工艺有望用于粉体材料的固相合成。     

退役汽车保险杠的同级回收利用

针对退役汽车保险杠塑料回收利用问题,提出了塑料喷丸表面除漆与回收料改性再生的技术方法。通过有限元仿真和实际除漆实验研究了保险杠表面塑料喷丸除漆的过程,仿真与实际实验结果说明了在80 m/s的垂直喷丸速度下,可以有效去除保险杠表面油漆,并且基体材料不受到破坏。在保险杠除漆回收料中添加聚丙烯(PP)新料、纳米蒙脱土(nano-MMT)、PP接枝马来酸酐(PP-g-MAH),通过双螺杆挤出机制备改性保险杠回收料,并测试了其拉伸与弯曲性能、缺口冲击强度、洛氏硬度和熔体流动速率,发现在除漆回收料/PP新料/nano-MMT/PP-g-MAH质量比为7/3/1/1的改性再生配方下,改性回收料的各项性能基本达到同级利用的标准要求,退役汽车保险杠材料的价值利用梯度得到提高。     

Multipath recycling method for transconductance enhancement of folded cascade amplifier

A multipath recycling method to enhance transconductance of the folded cascode amplifier is presented in this paper. The proposed method utilizes two idle paths to conduct small signal current, which leads to significant enhancement of transconductance compared to conventional folded cascade structure. Moreover, the improved performance is almost at no expense of power dissipation. The proposed multipath recycling and the conventional amplifiers are all designed in UMC 0.18 μm CMOS technology. Simulation results demonstrate that the transconductance of the proposed amplifier is improved by 450% and dc gain enhances 16 dB when compared with the folded cascode counterpart.     

废旧磷酸钒锂电池材料回收及再利用研究

针对磷酸钒锂电池材料溶解-沉淀回收困难的问题,采用Na OH溶液浸泡磷酸钒锂电极,溶解集流体铝箔,分析过滤产物中锂、钒、磷和碳的摩尔比,依据分析结果添加Li OH·H2O、V2O5、NH4H2PO4和蔗糖,使过滤产物和添加物的混合物中,锂、钒、磷和碳的摩尔比为3.15∶2∶3∶3,对混合物进行不添加酸和添加盐酸处理,在氩气气氛中于300℃下预烧结4 h,冷却和研磨后,再于氩气气氛中800℃下煅烧12 h,得到磷酸钒锂正极材料。与不经酸处理获得磷酸钒锂相比,X射线衍射(XRD)测试结果表明,经过酸处理工艺获得的磷酸钒锂结晶更好,其衍射峰与单斜结构磷酸钒锂谱图一致;扫描电子显微镜(SEM)测试结果表明,经过酸处理工艺获得的正极材料结晶粒径更小,粒径分布较均匀;能谱分析结果表明,产物中没有残存的氯;电化学测试结果表明,经过酸处理工艺获得的磷酸钒锂首次放电比容量为93.8m Ah/g,50次循环后的容量保持率为98.4%。     

Carbon Fiber Reinforced Thermoset Composite with Near 100% Recyclability

Both environmental and economic factors have driven the development of recycling routes for the increasing amount of composite waste generated. This paper presents a new paradigm to fully recycle epoxy‐based carbon fiber reinforced polymer (CFRP) composites. After immersing the composite in ethylene glycol (EG) and increasing the temperature, the epoxy matrix can be dissolved as the EG molecules participate in bond exchange reactions (BERs) within the covalent adaptable network (CAN), effectively breaking the long polymer chains into small segments. The clean carbon fibers can be then reclaimed with the same dimensions and mechanical properties as those of fresh ones. Both the dissolution rate and the minimum amount of EG required to fully dissolve the CAN are experimentally determined. Further heating the dissolved solution leads to repolymerization of the epoxy matrix, so a new generation of composite can be fabricated by using the recycled fiber and epoxy; in this way a closed‐loop near 100% recycling paradigm is realized. In addition, epoxy composites with surface damage are shown to be fully repaired. Both the recycled and the repaired composites exhibit the same level of mechanical properties as fresh materials.     

Eu2+掺杂Sr5(PO4)2SiO4磷灰石荧光粉的发光性能研究

采用高温固相法制备了Sr5－x (PO₄)₂SiO₄:xEu²⁺(x =0.010,0.015,0.020,0.025,0.050, 0.100)荧光粉,研究掺杂 浓度和测试温度对荧光粉发光性能的影响。随着Eu²⁺掺杂浓度的增加,发射强度呈现 先增大后减小的变化 趋势,并在x=0.015时达到最大值。Eu 2+掺杂浓度较低时(x≤0.025),Eu²⁺取代不同格位的 Sr²⁺,使得发射 光谱具有双发射峰;当x＞0.025时,由于 存在Eu 1到Eu 2的能量传递使发射光谱中Eu 1的峰位消失,只存 在Eu 2的峰位。发射光谱随Eu²⁺浓度增大出现了红移现象,这是由于半径较小的Eu 2+(0.109nm)取代较 大的Sr²⁺(0.113nm)使得晶胞收缩,晶场强度增大,从而导 致Eu²⁺的5d能级劈裂程度增大,电子跃迁释 放能量降低。此外,测试温度增加时,发射光谱出现与Varshini方程不相符的蓝移现象,这 是晶格结构稳定性和声子辅助隧穿效应共同作用使较小波长的Eu 1的发射居于主导地位的结 果。