Effect of concentration on R134a/Al2O3 nanolubricant mixture boiling on a reentrant cavity surface

This paper quantifies the influence of Al₂O₃ nanoparticles on the pool boiling performance of R134a/polyolester mixtures on a Turbo-BII-HP boiling surface. Nanolubricants with 10 nm diameter Al₂O₃ nanoparticles of various volume fractions (1.6%, 2.3%, and 5.1%) in the base polyolester lubricant were mixed with R134a at two different mass fractions (0.5% and 1%). The study showed that nanolubricants can improve R134a boiling on a reentrant cavity surface as long as the nanoparticles remain well dispersed in the lubricant and are at sufficiently large concentration. For example, three of the refrigerant/nanolubricant mixtures with the smallest nanoparticle mass fraction exhibited average enhancements over the entire heat flux range of approximately 10%. However, when the nanoparticle mass fraction was increased to a point that likely encouraged agglomeration, an average heat transfer degradation of approximately 14% resulted. An existing model was used to predict the boiling heat transfer.     

Reducing the migration of additives from plasticised poly(vinyl chloride)

This paper reports work studying the partial substitution of the commonly used plasticiser di-octyl phtalate (DOP) by the permanent plasticisers ethylene-vinyl-acetate (EVA) and acrylonitrile-butadiene-styrene (ABS) in order to reduce migration of additives initially present in poly(vinyl chloride) (PVC) stabilised with epoxidised sunflower oil (ESO). Various formulations with and without the two different permanent plasticisers were prepared. Their tensile properties were compared. Migration tests with agitation at 40°C in two food simulants (olive oil and 15% aqueous ethanol) were carried out. The mass variation of the PVC samples with time was investigated. Migration phenomena were studied by using various analytical methods such as Fourier transform infrared spectroscopy (FTIR), atomic absorption spectrometry (AAS) and scanning electron microscopy (SEM). The results showed that additives migration can be considerably reduced by partial substitution of DOP with both permanent plasticisers used. The best results were obtained with the binary system of plasticisers based on DOP:ABS (30:10).     

燃煤过程中添加剂的作用机理研究

从煤炭的燃烧过程出发，分析了燃煤过程中热值低的主要原因。通过实验测定、理论计算和文献查找，证明添加剂能够降低燃点、促进燃烧、增加热值，并提出了添加剂的作用机理。添加剂一方面促进煤的盐基交换，使煤成为着火性能较好的腐植酸盐，另一方面使煤分子断裂成相对较小的分子，有利于析出挥发分和煤的热传导。同时使用不同的添加剂，可以在不同温度下释放出活性氧，有利于煤的完全燃烧。添加剂的作用机理为添加剂的研究提供了理论指导。     

用于珠光颜料的片状氧化铝制备

采用熔融盐法制备片状α-Al2O3,研究了硫酸盐、煅烧温度、添加剂(磷酸盐、二氧化钛)对片状α-Al2O3晶体形貌的影响。当氢氧化铝凝胶煅烧温度为900℃时,没加硫酸盐分解所得的氧化铝晶相为κ-Al2O3晶相,而加入硫酸盐的氧化铝晶相为α-Al2O3晶相,熔融盐降低了片状α-Al2O3的形成温度,促进κ-Al2O3向α-Al2O3晶型转变。煅烧温度由900℃上升到1200℃时,片状α-Al2O3的团聚程度降低,颗粒尺寸分布更加均匀。当煅烧温度在1200℃下、磷酸盐添加量为3%、二氧化钛添加量为2%时,所制得片状氧化铝分散均匀,径厚比较大,片状氧化铝平均粒径为5.225μm、厚度约400-500 nm。     

Food Additives Reducing Volatility of Antioxidants at Frying Temperature

At frying temperature, antioxidants are lost not only by reaction with radicals formed by oil oxidation but also by decomposition and evaporation before they are able to exert antioxidant activity. In this study, it was hypothesized that an additive that can bind or interact with an antioxidant could reduce volatility of the antioxidant at frying temperature. Three synthetic antioxidants, tert‐butylhydroquinone (TBHQ), butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT), which have relatively high volatility, were used as antioxidants in this study to examine the hypothesis. Thermogravimetric analysis (TGA) experiments showed that all 22 additives tested in this study effectively reduced volatility of the antioxidants. An NMR study showed that signals of BHT shifted by addition of an additive, evidencing the interaction between the two substances in the chloroform solution. To examine the effect of these interactions on antioxidant activity, heating tests were conducted with soybean oil (SBO) containing 200 ppm antioxidants at 180 °C. Oxidation was monitored with ¹H NMR for loss of olefinic protons and bisallylic protons in SBO and with gel permeation chromatography (GPC) for polymerized triacylglycerols (PTAG). Improved antioxidant activity of the antioxidants were observed when combined with several additives tested in this study, and HPLC analysis showed that the antioxidants were effectively reserved by the additives in SBO during the heating process. The concentrations of the antioxidants retained in SBO were relatively well correlated with the antioxidant activity.     

Influence of a cyclic butylene terephthalate oligomer on the processability and thermoelectric properties of polycarbonate/MWCNT nanocomposites

The thermoelectric properties of melt-processed nanocomposites consisting of a polycarbonate (PC) thermoplastic matrix filled with commercially available carboxyl (–COOH) functionalized multi-walled carbon nanotubes (MWCNTs) were evaluated. MWCNTs carrying carboxylic acid moieties (MWCNT-COOH) were used due the p-doping that the carboxyl groups facilitate, via electron withdrawing from the electron-rich π-conjugated system. Preliminary thermogravimetric analysis (TGA) of MWCNT-COOH revealed that the melt-mixing was limited at low temperatures due to thermal decomposition of the MWCNT functional groups. Therefore, PC was mixed with 2.5 wt% MWCNT-COOH (PC/MWCNT-COOH) at 240 °C and 270 °C. In order to reduce the polymer melt viscosity, a cyclic butylene terephthalate (CBT) oligomer was utilized as an additive, improving additionally the electrical conductivity of the nanocomposites. The melt rheological characterization of neat PC and PC/CBT blends demonstrated a significant decrease of the complex viscosity by the addition of CBT (10 wt%). Optical and transmission electron microscopy (OM, TEM) depicted an improved MWCNT dispersion in the PC/CBT polymer blend. The electrical conductivity was remarkably higher for the PC/MWCNT-COOH/CBT composites compared to the PC/MWCNT-COOH ones. Namely, the PC/MWCNT-COOH/CBT processed at 270 °C exhibited the best values with electrical conductivity; σ = 0.05 S/m, Seebeck coefficient; S = 13.55 μV/K, power factor; PF = 7.60 × 10⁻⁶μW/m K⁻², and thermoelectric figure of merit; ZT = 7.94 × 10⁻⁹. The PC/MWCNT-COOH/CBT nanocomposites could be ideal candidates for large-scale thermal energy harvesting, even though the presently obtained ZT values are still too low for commercial applications.     

优质硅砖生产中原料除铁工艺及添加剂自动添加系统的研发

为提高硅砖的成品率和性能指标,进一步降低产品能耗,研究了硅砖生产过程中容易影响制品性能和成品率的关键环节和设备,并参考国内外先进技术,研发出原料除铁工艺及添加剂、矿化剂自动添加系统,确定了优质硅砖生产线相应环节的最佳技术方案,最大限度地提高了成品质量并降低能耗。     

催化裂化抗氮中毒技术的研究进展

从调节催化剂酸性或向反应体系外加抗氮剂的角度,介绍了加强催化裂化抗氮中毒能力,以增产汽油、柴油、丙烯或抑焦为目的的研究进展。针对于调变催化剂本身的酸性存在灵活性差、成本高的缺点,认为开发性优价廉的抗氮助剂改善原料质量,减缓催化剂中毒是有前景的抗氮中毒技术。     

Effect of CuO addition on electrochemical properties of AB3-type alloy electrodes for nickel/metal hydride batteries

In order to improve overall electrochemical properties of AB₃-type hydrogen storage alloy electrodes, especially the cycling stability, CuO was added to the electrode. Electrochemical properties of the electrodes with and without additives were studied. Cyclic voltammetry and SEM results show that CuO is reduced to Cu during the charging process and the fine Cu particles deposit at surface of the alloy particles. The as-deposited Cu particles form a protective layer to increase electronic and heat conductivity of the electrodes and thus improve maximum discharge capacity, high rate dischargeability, cycling stability and dischargeability at high temperature of the electrodes. The maximum discharge capacity increases from 314 mAh g⁻¹ (blank electrode) to 341 mAh g⁻¹ (3.0 wt.% CuO) and the capacity retention rate at the 200th cycle increases from 71.6% to 77.2% (2.5 wt.% CuO).     

镁合金化学镀及其添加剂研究

针对镁合金化学镀中常存问题,根据经验精选了镁合金化学镀的前处理工艺和镀镍液配方,根据该工艺得到的镀层试验检测表明具有耐腐蚀性强、硬度高、结构致密、光泽性好且有一定延展性;同时通过实验比较了四种添加剂对镁合金化学镀镀速及镀液稳定性的影响,得出了钇和铕对镀液的稳定性影响较大,氟化铵和碳酸钠对镀速的影响较为显著,尤其是添加的Y3 浓度为0.02g/L时,镀液的稳定性提高最多,而碳酸钠在19g/L左右时加速作用最为明显.并分析了它们的影响机理.