福建杉/改性脲醛树脂胶制备轻质人造板的实验研究

以福建杉木微米级长薄刨花和改性脲醛树脂胶粘剂为原料,在实验室压制了轻质人造板材。采用单因素对比实验,就施胶量对板材的物理力学性能的影响规律进行了研究。实验结果表明:板材外观呈现木本色,施胶量对福建杉/改性脲醛树脂胶轻质人造板的静曲强度(MOR)、内结合强度(IB)、握螺钉力均有显著影响;当施胶量为30%时,所制备的密度为0.3,0.4和0.5 g/cm3的福建杉/改性脲醛树脂胶轻质人造板的物理力学性能,均能达到《日本轻质刨花板工业标准JISA5908》的各项性能指标。     

微米级可膨胀石墨的制备和表征

选择冰醋酸和浓硫酸为插层物质,从反应物配比、反应温度、反应时间、干燥温度等方面探讨了微米级可膨胀石墨的制备工艺,并对产品粒径、表面形貌和红外消光能力进行了表征。实验结果表明,选择合适的反应物,并控制好反应物比例、反应温度和时间以及干燥温度等工艺条件,即可制得符合要求的微米级可膨胀石墨,该石墨在中、远红外区比微粉石墨具有更好的红外消光能力。     

Modification of the morphology of Na3V2(PO4)2F3 as cathode material for sodium-ion batteries by polyvinylpyrrolidone

NASICON-type Na₃V₂(PO₄)₂F₃ (NVPF) is proposed to be a potential cathode material for sodium-ion battery because of its good structural stability, relatively high capacity and voltage platform. Nonetheless, the poor-rate performance, resulting from its low conductivity, has become a massive obstacle to its practical application. In this work, carbon coating together with morphology controlling were introduced to solve the issue of NVPF. This experiment used a hydrothermal method to prepare Na₃V₂(PO₄)₂F₃@C (NVPF@C) and explored the impact of surfactants (polyvinylpyrrolidone (PVP)) on the positive material performance of sodium-ion battery. Through various characterisation, NVPF@C compared its performance with that of untreated products, and verified that appropriate surfactant modification could enhance the performance of the electron conduction and sodium ion diffusion, thus effectively improved the performance of NVPF. Through comparison, it was found that appropriate surface modification with PVP can achieve the effects of specific crystal surface exposure and clusters of porous micron ball structure, and improve the electrochemical performance of NVPF best. Under the charge and discharge ratio of 0.2C, its initial reversible capacity was 127.8 mA h g^?1. After 100 cycles, its discharge capacity was 106.1 mA h g^?1, and the cycling retention rate reached 82.8%. Compared to the original NVPF, its performance has been dramatically improved.     

微米／纳米金刚石膜的性能和应用

从现今已知的材料而言，金刚石集力学、电学、热学、声学、光学以及化学惰性等如此多的优异性于一身，这正是科技工作者所期望的，而且也正是其吸引如此众多的跨学科的科技工作者投入研究的缘故。金刚石膜是21世纪有发展前途的新型材料，日本、美国和欧洲工业界正在大力开发金刚石膜的应用。通过广大科技工作者的深入研究，大胆实践，无论是生长理论、方法和应用都取得了重大突破，使得其在现代科学技术和现代工业的高速发展中发挥重要作用。     

印版分辨率的检测

为了获得印版的分辨率,使用印版质量控制条对被测印版施加曝光系列,检测和分析已曝光印版上的微米线区.通过实验研究,可以将印版的分辨率确定为它能在某一曝光量下同时再现的相同宽度的阳像和阴像线条的微米数;通过改变曝光系列,总是可以在印版上复制出某一曝光量下相同微米数的阳像和阴像线条.     

微米锆粉的热氧化过程研究

为探究微米锆粉的热氧化过程,进行锆粉氧化反应动力学分析,通过激光粒度分析、扫描电子显微镜(SEM)和X射线衍射仪(XRD)等方法对所研究锆粉颗粒的粒径分布、微观形貌、元素含量以及物相特征进行了研究。通过热重分析法(TG)和差示扫描量热法(DSC)开展了不同升温速率的氧化过程研究,得到不同升温速率下锆粉氧化的DSC-TG曲线,进一步分析得到锆粉热氧化的动力学参数以及反应模型。结果表明,锆粉样品的粒径主要分布在15～46μm,颗粒形状不规则,且主要包含Zr元素,锆粉颗粒主要物相为金属Zr;锆粉氧化过程可以分为初始氧化,加速氧化、剧烈氧化和反应平衡四个阶段;锆粉的非等温氧化过程符合随机成核和随后生长模型函数,其积分表达式为G (α)=[-ln(1-α)]~(5/2)。因此微米锆粉热氧化反应动力学的活化能E_a为175.83 kJ·mol~(-1),指前因子A=1.91×108s~(-1),反应速率常数k=1.91×10~8exp(-2.1×10~4/T)。     

Pechini法制备TiO_2薄膜及其在染料敏化太阳电池中的应用

用Pechini法在FTO导电玻璃上制备不同厚度的TiO2薄膜,并组装成染料敏化太阳能电池。XRD结果表明,在450℃退火1h得到了主相为锐钛矿的TiO2。SEM结果表明,TiO2薄膜表面疏松多孔,粒径均匀,厚度在6~15μm。紫外-可见光谱分析表明,TiO2薄膜染料的吸附量随薄膜厚度的增加而增加。光电性能研究表明,在0.005W/cm2的弱光照下,膜1(厚6μm)和膜2(厚15μm)光阳极的光电转换效率分别为6.85%和11.83%;在0.1 W/cm2的模拟标准太阳光照下,膜1和膜2光阳极的光电转换效率分别为1.72%和2.39%。     

A comparative study of submicron‐ and micron‐sized rice particles: enzymatic hydrolysis in vitro and food efficiency ratio in vivo

Hydrolysis and absorption properties of submicron‐ (below 1 μm) and micron‐sized (over 100 μm) powders of raw rice, heat‐gelatinized rice, fermented rice and wheat were investigated in vitro and in vivo. Nutrient content such as protein, carbohydrate or vitamin C in the samples was not different significantly between submicron‐ and micron‐sized powders, but it showed difference according to processed type of the powders. Submicron‐sized powders were hydrolyzed more easily than micron‐sized powders by α‐amylases such as industrial, human salivary and porcine pancreatic α‐amylase but not by α‐glucosidase in all the tested samples. Patterns of blood glucose change were investigated in rats. The highest glucose levels were obtained at 30 min after oral administration in both submicron‐and micron‐sized powders, but the levels were decreased drastically in groups administered submicron‐sized powders, while they were slow and gradual in groups administered micron‐sized powders. On the contrary, the body weight gained and food efficiency ratios showed a tendency to be decreased slightly in mice fed with submicron‐sized rice powders compared to those with micron‐sized rice powder.     

微纳米金属铁粉的燃烧特性试验研究

运用热重分析手段对微纳米尺度金属铁粉燃料的着火和燃烧特性进行了研究.通过不同微米、纳米尺度金属铁粉燃烧过程的热重试验,分析不同粒径金属铁粉的燃烧特性,计算不同微米、纳米尺度金属铁粉在空气中燃烧的着火点、最高燃烧温度和表观活化能.结果表明,30～110nm粒径范围的纳米尺度铁粉的平均着火温度为280℃左右,最高燃烧温度为750～950℃,表观活化能为20～30kJ/mol;2～5μm亚微米级铁粉着火点为380℃,最高燃烧温度为950～990℃,表观活化能为37kJ/mol;而40μm的微米级铁粉着火温度为600℃左右,最高燃烧温度达到1000℃,表观活化能为58kJ/mol.随着颗粒粒径从微米减小到纳米尺度,金属颗粒的比表面积迅速增大,造成TG/DTG曲线上最大增重梯度所对应的反应温度和最高燃烧温度均明显降低,燃烧着火点温度明显降低,表观活化能迅速减小,因此反应活性随粒径的减小迅速提高.