芳纶纤维增强丁腈橡胶的摩擦性能

研究了芳纶纤维增强丁腈橡胶(NBR)复合材料的物理机械性能和摩擦性能,并用扫描电子显微镜分析了芳纶纤维增强NBR复合材料的磨损表面和磨屑形貌。结果表明,芳纶的加入提高了NBR的拉伸强度;随着芳纶用量的增大,复合材料的扯断伸长率降低;芳纶的加入降低了NBR的摩擦系数和磨损率;当芳纶用量为20份时,复合材料的综合性能最佳。加入芳纶对NBR摩擦磨损形式的改变是NBR摩擦性能提高的重要原因。     

4种马来酸酐接枝物对PA66/TLCP共混物界面的增容作用

利用差示扫描量热法（DSC）和傅里叶红外光谱法（FTIR）研究了4种马来酸酐接枝聚合物对聚酰胺66／热致性液晶聚合物（PA66／TLCP）共混物界面的增容作用,并对PA66／TLCP共混物进行了力学性能测试和扫描电子显微镜（SEM）的微观形貌研究。DSC结果表明,4种马来酸酐接枝聚合物对PA66／TLCP共混物的熔融温度、熔融焓、结晶温度、过冷度和结晶度均有不同程度的影响;FTIR证明共混物界面发生增容反应。4种马来酸酐接枝聚合物对PA66与TLCP的界面相容性均有不同程度的改善,使共混物的力学性能提高,且改变了分散相在基体中的分散形态。     

OMS-2催化剂成型工艺研究及其在印染废水处理中的应用

以OMS-2粉体催化剂为基础,对催化剂进行挤出成型,考察粘结剂种类、粘结剂用量、润滑剂和孔结构改进剂用量、焙烧温度对成型催化剂机械强度的影响。得到最佳成型工艺条件为,粘结剂硅溶胶用量为OMS-2粉体催化剂质量的105%～110%、辅助粘结剂纳米ZrO_2用量为OMS-2粉体催化剂质量的30%～35%、润滑剂田菁粉用量为OMS-2粉体催化剂质量的2. 5%～3. 0%、孔结构改进剂柠檬酸用量为OMS-2粉体催化剂质量的5%～6%,焙烧温度450℃。成型后催化剂机械强度可达150 N·cm~(-1),满足工业化应用对催化剂强度的要求。将成型催化剂应用于催化湿式氧化印染废水处理,经过432 h活性评价时间,COD平均去除率约91. 6%,反应结束后催化剂结构完整,平均机械强度约144 N·cm~(-1),表现出良好的水热稳定性。     

Microstructural evaluation and thermal oxidation behaviors of YSZ/NiCoCrAlYTa coatings deposited by different thermal techniques

In this paper, two coating techniques, the high velocity oxy-fuel (HVOF) and air plasma spray (APS) techniques, were used to deposit a bond coat of NiCoCrAlYTa on the Inconel 625 substrate, followed by applying a topcoat of yttria-stabilized zirconia (YSZ). The samples were preoxidized in an argon-controlled furnace at a temperature of 1000 °C for 12 and 24 h to characterize the microstructure of a thermally grown oxide (TGO) using the two coating techniques. The most suitable preoxidized samples were further tested for isothermal oxidation at 1000 °C for up to 120 h, and a hot corrosion test was performed at 1000 °C for up to 52 h or until spalling occurred. As-sprayed and oxidized samples prepared with different coating techniques were evaluated in terms of their microstructure using different characterization methods, such as field emission scanning electron microscopy (FESEM), variable pressure scanning electron microscopy (VPSEM), energy dispersive X-ray spectroscopy (EDS) equipped with energy dispersive X-ray and X-ray diffraction (XRD) analyses. In addition, the mechanical properties of these samples were evaluated using adhesion tests. The results show that the YSZ/NiCoCrAlYTa coating applied with the HVOF technique forms a more thin and continuous layer of TGO than that obtained when applying a YSZ/NiCoCrAlYTa coating using the APS technique, indicating that a severe brittle oxidation interface exists between the two layers. The results also indicate that the mechanical strength obtained from the adhesion test of the coated samples is observably affected by the oxidation behaviors obtained with the different deposition techniques chosen.     

Mechanical properties and thermal stability of porous polyimide/hollow mesoporous silica nanoparticles composite films prepared by using polystyrene microspheres as the pore-forming template

The porous polyimide/hollow mesoporous silica nanoparticles (PI/HMSNs) composite films were fabricated via blending polymerization by using polystyrene (PS) microspheres as the pore-forming template. The morphologies, microstructures, thermal stability, thermal expansion coefficient (TEC), and mechanical performances of the porous PI/HMSNs films were characterized in detail. Results showed that the uniform dispersion of HMSNs benefits from the strong hydrogen-bonding interaction between the hydroxyl groups of HMSNs and poly(amic acid) chains. Both weight loss and TEC of the porous PI/HMSNs films are lower than those of the pure porous PI film. When 0.8 wt % HMSNs and 7.0 wt % PS were added into the PI matrix, the Young's modulus and tensile strength of composite film increased by about 32.4% and 68.1% compared with those of the pure porous PI film. Conclusively, the introduction of HMSNs in the porous PI matrix is an important strategy to enrich the diversity of porous structure, improve the thermal and mechanical properties of the porous PI material simultaneously. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48792.     

Effect of ZrO2 nanoparticles addition to PEO coatings on Ti–6Al–4V substrate: Microstructural analysis,corrosion behavior and antibacterial effect of coatings in Hank's physiological solution

In this study, plasma electrolyte oxidation (PEO) method was employed to modify the surface of Ti–6Al–4V. Effects of different concentrations of ZrO₂ nanoparticles (0, 1, 3 and 5 g/l) into a phosphate-based electrolyte on the morphology, wettability, antibacterial and corrosion behaviors of coatings were investigated. Microstructural analyses of coatings were evaluated using scanning electron microscopy with an energy dispersive spectrometer. Also, X-ray diffraction, contact angle instrument and profilometry were respectively used to perform phase analysis, wettability, and surface roughness of the coatings. The antibacterial test was conducted with spot inoculation method on four pathogenic bacteria. Polarization and impedance spectroscopy measurements were performed in Hank's solution to investigate the corrosion behavior of coatings. The results revealed that PEO coatings without nanoparticles and by increasing the concentration of the ZrO₂ nanoparticles up to 3 g/l in the electrolyte led to a significant improvement in the antibacterial activities of gram-negative bacteria (P. aeruginosa and E. Coli). In the case of gram-positive bacteria, the PEO coated samples demonstrated improved antibacterial effects but addition of ZrO₂ nanoparticles in the PEO coatings resulted in deterioration of antibacterial effect. The sample coated with 3 g/l ZrO₂ nanoparticles showed the peak corrosion resistance compared to its counterparts.     

Thermal annealing characteristics of solar selective absorber coatings based on nano-multilayered MoOx films

Designing double metal-dielectric (cermet) solar selective absorber coatings (SSACs) often requires complex co-sputtering techniques with multiple targets. This inevitably limits the simple and low-cost industrial fabrication. Here, we develop novel nano-multilayered MoO_x-based SSACs by simple and stable one-step reactive magnetron sputtering process using single molybdenum target. The proposed multilayer SSACs exhibit good solar absorptance of 0.93 and low thermal emittance of 0.06. Owing to the temperature-induced oxygen diffusion and oxidation phenomenon the as-sputtered SSACs have a poor thermal tolerance under air atmosphere, and after annealing at 200 °C for 150 h, the resulting absorptance is diminished from 0.93 to 0.90. However, the optical performance of the annealed SSAC is relatively stable in high-vacuum environment, even after annealing at 450 °C for 200 h, it still displays an ideal spectral selectivity of 0.92/0.07. With above properties, the resulting MoO_x-based SSAC is a promising absorber for enduring thermal harvesting in solar vacuum collectors.     

Preparation and properties of amorphous Co-P and Co-Ni-P films

Amorphous Co-P and Co-Ni-P films were prepared by electrodeposition on a moving substrate. Chemical composition of the films was controlled mainly by temperature for the Co-P films and by current density for the Co-Ni-P films. The B-H loops indicate the differences between films deposited on stationary substrates and those deposited on moving substrates. Specific magnetization measurements were carried out after substrate dissolution in acid.     

牡蛎蛋白酶解多肽降糖及抗氧化活性评价

目的:利用化学方法评价9种酶对牡蛎蛋白酶解所得多肽降血糖和抗氧化活性的影响,筛选最佳酶的种类。方法:以牡蛎蛋白酶解多肽对α-淀粉酶抑制率为指标评价其体外辅助降血糖活性,以DPPH·清除率、超氧阴离子抑制率为指标评价牡蛎蛋白酶解多肽的体外抗氧化活性,筛选出最佳用酶。结果:风味蛋白酶得到的多肽对α-淀粉酶的抑制效果最好,5 mg/mL时抑制率达到67.13%,IC₅₀值为3.806 mg/mL;糜蛋白酶酶解得到的多肽对DPPH·的清除率最高,2 mg/mL时清除率为58.09%,IC₅₀值为1.16 mg/mL;同时,糜蛋白酶酶解得到的多肽对超氧阴离子的抑制率也最高,2 mg/mL时抑制率为53.64%,IC₅₀值为1.75 mg/mL。结论:风味蛋白酶和糜蛋白酶酶解所得牡蛎多肽在降糖和抗氧化方面具有较大的潜力,为进一步开展牡蛎蛋白酶解多肽的研究提供参考。     

红酵母发酵废糖蜜产类胡萝卜素的研究

对红酵母利用糖蜜发酵产类胡萝卜素进行了研究,结果表明:对糖蜜的预处理的最佳酸为硫酸;利用经过酸处理后的糖蜜发酵,菌株的生物量为30.75g/L,单细胞色素含量为104μg/g,色素产量为26mg/L;最佳发酵时间为168h.使用糖蜜代替葡萄糖做廉价碳源对红酵母进行发酵,确定添加量为170g/L,色素产量最大值为葡萄糖发酵的0.97倍,生物量为1.04倍.