双层桨搅拌槽内部流场的实验研究

运用计算流体动力学（CFD）方法对双层桨搅拌槽内部流场进行数值模拟。考察了流体在不同桨叶类型、不同桨叶间距对搅拌槽内宏观流动场的影响。研究发现：流体在桨叶间距为150 mm的双层桨内部流场流动效果好。在此间距的基础上得出流体在六圆盘上斜叶桨的搅拌槽内比六圆盘直叶桨搅拌槽内混合效果好。     

Effect of the matrix resin structure on the mechanical properties and braking performance of organic brake pads

Two chemically modified phenolic resins (PFs) designed and developed for the matrix resins of organic friction materials were characterized. The braking performance of organic brake pads based on the two modified resins and reinforced with hybrid fibers was investigated on a full‐scale test bench. The results indicate that the modified PF with more internal friction units possessed much higher impact and compression strengths, greater toughness, and better braking stability. We concluded that the matrix resin with more adjustable structural units allowed for an adjustable Young's modulus and dynamic mechanical properties and, hence, could indirectly allow an adjustable friction coefficient for organic brake pads during braking process and, furthermore, enable the optimization of braking stability of the friction couples. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2012     

Cumene Hydroperoxide Hydrogenation on a Pd/Al2O3 Catalyst in a Trickle Bed Reactor – Kinetics of Hydrogenation and Deactivation

Liquid‐phase hydrogenation using a Pd/Al₂O₃ catalyst provides a potential technique for the reduction of cumene hydroperoxide (CHP) to α‐cumyl alcohol (CA). In this paper, CHP hydrogenation was carried out in a cocurrent downflow trickle‐bed reactor over a wide range of reaction conditions to study the reaction and deactivation kinetics. The proposed intrinsic rate expression for CHP hydrogenation is based on an Eley‐Rideal mechanism that accounts for an irreversible surface reaction between the absorbed CHP with nonabsorbed hydrogen molecules. During CHP hydrogenation, an exponential decay in activity of the Pd/Al₂O₃ catalyst and the presence of residual activity were observed. A kinetic deactivation model with residual activity was developed. Based on reaction and deactivation kinetics, catalyst deactivation was attributed to oxidation of the catalyst surface by CHP. The presence of residual activity was due to the partial reduction of oxidized catalyst surface by hydrogen.     

Effects of acid treatment on adhesive performance of encapsulated aluminium pigments on plastic sheets

In this study, aluminium pigments were encapsulated with hydroxyl group‐containing acrylic resin after surface acid treatment to enhance their adhesive performance in the paint film. The removal efficiency of fatty acid on surface of aluminium particles was studied by means of thermogravimetric analysis and the effect of acid treatment on adhesive performance of aluminium pigments encapsulated with hydroxyl group‐containing acrylic resin in the paint film was investigated by pulling‐off tests. It was found that fatty acid on surface of aluminium particles was removed efficiently by acid ethanol solution, and then hydroxyl group‐containing acrylic resin can be encapsulated onto the surface of the aluminium particles by chemisorptions. The encapsulated aluminium pigments have excellent adhesive performance in the paint film. © 2011 Canadian Society for Chemical Engineering     

Gas‐Liquid Mass Transfer Characteristics in a Rotating‐Drum Bioreactor

The oxygen volumetric mass transfer coefficient is a key parameter to characterize the performance of aerobic bioreactors. A novel rotating‐drum bioreactor (RDB) fitted with a sparger as proposed in a previous work has demonstrated its excellent gas‐liquid mass transfer performance. To provide primary information on the design and scale‐up of the novel RDB, effects of reactor configuration including the number and width of lifters and operation conditions such as rotational speed, aeration rate, and solid volume fraction on mass transfer performance were systematically investigated in a new medium‐sized RDB. Compared with the stirred bioreactor and traditional RDBs, this new RDB exhibits better mass transfer performance. Taking both operational and reactor configuration parameters into consideration, an empirical correlation to predict the volumetric mass transfer coefficient in this type of RDBs was proposed which is valuable for its design and scale‐up.     

Novel bioresorbable hydrogels prepared from chitosan‐graft‐polylactide copolymers

A series of biodegradable chitosan‐graft‐polylactide (CS‐g‐PLA) copolymers were prepared by grafting of poly(L ‐lactide) (PLLA) or poly(D ‐lactide) (PDLA) precursor to the backbone of chitosan using N,N′‐carbonyldiimidazole as coupling agent. The composition of the copolymers was varied by adjusting the chain length of PLA as well as the ratio of chitosan to PLA. The copolymers synthesized via this ‘graft‐onto’ method present interesting properties as shown by NMR and infrared spectroscopy, gel permeation chromatography and solubility tests. Hydrogels were prepared by mixing water‐soluble CS‐g‐PLLA and CS‐g‐PDLA solutions. Gelation was assigned to stereocomplexation between PLLA and PDLA blocks as evidenced by differential scanning calorimetry and wide‐angle X‐ray diffraction measurements. Thymopentin (TP5) was taken as a model drug to evaluate the potential of these CS‐g‐PLA hydrogels as drug carriers. An initial burst and a final release up to 82% of TP5 were observed from high‐performance liquid chromatography analysis. Copyright © 2011 Society of Chemical Industry     

A cross‐cultural comparison of colour emotion for two‐colour combinations

Psychophysical experiments were conducted in the UK, Taiwan, France, Germany, Spain, Sweden, Argentina, and Iran to assess colour emotion for two‐colour combinations using semantic scales warm/cool, heavy/light, active/passive, and like/dislike. A total of 223 observers participated, each presented with 190 colour pairs as the stimuli, shown individually on a cathode ray tube display. The results show consistent responses across cultures only for warm/cool, heavy/light, and active/passive. The like/dislike scale, however, showed some differences between the observer groups, in particular between the Argentinian responses and those obtained from the other observers. Factor analysis reveals that the Argentinian observers preferred passive colour pairs to active ones more than the other observers. In addition to the cultural difference in like/dislike, the experimental results show some effects of gender, professional background (design vs. nondesign), and age. Female observers were found to prefer colour pairs with high‐lightness or low‐chroma values more than their male counterparts. Observers with a design background liked low‐chroma colour pairs or those containing colours of similar hue more than nondesign observers. Older observers liked colour pairs with high‐lightness or high‐chroma values more than young observers did. Based on the findings, a two‐level theory of colour emotion is proposed, in which warm/cool, heavy/light, and active/passive are identified as the reactive‐level responses and like/dislike the reflective‐level response. © 2010 Wiley Periodicals, Inc. Col Res Appl, 2012     

Annealing effect on chain segment motion and charge detrapping in polyamide 610

The chain segment motion and charge detrapping in polyamide 610 films have been investigated by means of thermally stimulated depolarization current (TSDC) and wide‐angle X‐ray diffraction. There are three current peaks (namely α, ρ₁, and ρ₂ peaks) in the TSDC spectra above room temperature. α peak is attributed to a dipole relaxation by the motion of chain segments ρ₁ peak is caused by space charge trapped in amorphous phase and the interphase between crystalline and amorphous phases, and ρ₂ peak is brought about by space charge trapped in crystalline phase. By analyzing the characteristic parameters of these peaks, it is found that annealing induces the decrease of chain segment mobility and promotes the creation of structural traps in polyamide 610. The decrease of chain segment mobility in amorphous phase makes intensity of α peak weak and activation energy increscent. The higher the annealing temperature, the higher the degree of crystallinity, the more the charge carriers trapped in crystalline phase. So, the increase of degree of crystallinity makes intensity of ρ₂ peak strong and increases the stability of trapped charge in the crystalline phase. The increase of annealing temperature makes intensity of ρ₁ peak strong and decreases the stability of trapped charge in the amorphous phase and interphase. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

基于大豆蛋白的高回弹聚氨酯泡沫塑料的制备及性能研究

以大豆分离蛋白、高活性聚醚、聚合物多元醇、交联剂、发泡剂、泡沫稳定剂和混合异氰酸酯为原料,自由发泡、常温熟化制备了大豆蛋白基高回弹聚氨酯软泡。研究了大豆蛋白质(SPI)对聚氨酯泡沫物理性能、力学性能、孔结构和热性能的影响。结果表明:SPI添加量对泡沫物理和力学性能影响最大。随着SPI含量增加,泡沫的密度、尺寸稳定性提高,压陷硬度和舒适因子提高增大;回弹率下降,断裂伸长率减小,而拉伸强度先增大后减小。SPI能够提高聚氨酯的热稳定性,但最好低于150℃使用。     

Polyoligomeric silsesquioxane (POSS)–hydrogenated polybutadiene polyurethane coatings for corrosion inhibition of AA2024

A series of coatings were developed that help prevent corrosion of aluminum alloy 2024 (AA2024). The coatings were based on an aliphatic polyurethane–polyoligomeric silsesquioxane (PU–POSS) resin. The materials were selected to exhibit a high level of hydrophobicity, which is expected to increase the moisture barrier properties, and thereby improve corrosion prevention. In addition, corrosion inhibitors (free molecules or encapsulated) were introduced into the coatings to improve corrosion resistance. The performance of the coatings was quantified using electrochemical impedance spectroscopy (EIS) and salt fog testing. Results from various formulations show that the hardness of the coating can be controlled by adjusting the ratio of POSS to hydrogenated hydroxyl terminated polybutadiene in the formulation. The coatings also had remarkable barrier properties, fast curing, and very high adhesion to the treated AA2024 substrate, all of which are expected to improve the anti-corrosion properties of the coatings. The best corrosion protection of AA2024 was observed in a transparent 10 μm thick PU–POSS bilayer coating that contained a mixture of sodium-2-mercaptobenzothiazole (i.e., NACAP) and benzotriazole-laden hydrotalcite. It was found that only certain corrosion inhibitors (free molecules or encapsulated) improve the anti-corrosion properties of the coating, whereas other corrosion inhibitors may actually degrade the coating performance.