The Adhesion of Irregularly-shaped 8 μm Diameter Particles to Substrates: The Contributions of Electrostatic and van der Waals Interactions

The forces needed to remove irregularly-shaped, 8 μm diameter, polyester particles from a polyester substrate were measured using an ultracentrifuge. Measurements were also made on a second set of similar particles where nanometer-size silica clusters had been placed on their surfaces. These silica clusters acted as spacers, reducing direct contact between the particle and the substrate. It was found that the separation forces for the bare particles were consistent with predictions of the JKR theory of adhesion, but were much larger than could be accounted for from simple electrostatic interactions associated with either uniformly-charged particles or particles with localized charged patches. It was found, however, that the forces needed to effect separation decreased with increasing silica concentration. For particles with 2% by weight silica clusters on their surfaces, the separation force was only about 5% of the separation forces of the bare particles. At this concentration of silica, the estimates of the separation forces obtained from JKR theory, from the uniformly-charged model, and from the localized-charged-patch model are all about equal. The numerical estimates are consistent with the experimentally-obtained values.     

Production of Monoacylglycerols from Fully Hydrogenated Palm Oil Catalyzed by Hydrotalcite Loaded with K2CO3

This study reports a new method of producing high-purity monoacylglycerols (MAGs) by glycerolysis of fully hydrogenated palm oil (FHPO) catalyzed by hydrotalcite loaded with K₂CO₃ (K₂CO₃/HT). The effects of reaction temperature, reaction time, catalyst (K₂CO₃/HT) loading, and mass ratio of FHPO to glycerol on glycerolysis were investigated. The selected conditions included a reaction temperature of 200°C, K₂CO₃/HT loading at 0.8 wt.% (FHPO mass), a 5:2 mass ratio of FHPO to glycerol, and a reaction time of 2 h. Under these selected conditions, the yield of MAGs in the acylglycerol phase reached 46.8 wt.%. A two-stage molecular distillation was introduced to purify MAGs, and the final MAG product was obtained with a purity of 96.6 wt.% and a recovery of 96.8%. Furthermore, the recycled K₂CO₃/HT was reactivated with restored catalytic efficiency through impregnation, carbonation, and recalcination.     

氧瓶燃烧法测定Si-69的全硫含量

采用氧瓶燃烧法测定双-(γ-三乙氧基硅基丙基)四硫化物(Si-69)的全硫含量,以过氧化氢溶液为吸收液,酚酞为指示剂,用氢氧化钠标准溶液直接滴定。探讨了该方法的精密度和准确度。结果表明,方法的相对标准偏差(RSD)<2%,与国标方法无显著性差异,相对误差≤2%。该方法简便、准确、成本低,还有快速的优点,可用于Si-69的全硫质量控制分析。     

炉顶MN管导烟车的应用效果

引进了炉顶MN管导烟车及机侧炉门密封装置,利用高压氨水的高速喷射在桥管内形成局部负压,使装煤产生的荒煤气在负压作用下抽入集气管,进行回收利用,解决了炉头和炉顶烟气外逸的问题,具有较好的环保和经济效益。     

Separate versus Simultaneous Saccharification and Fermentation of Two‐Step Steam Pretreated Softwood for Ethanol Production

Abstract

In two previous studies, optimal conditions were identified for two‐step steam pretreatment of SO₂‐ and H₂SO₄‐impregnated softwood. In the present study the yield of sugar and ethanol was determined in a process development unit where pretreatment was performed in a 10‐L reactor and simultaneous saccharification and fermentation (SSF) or enzymatic hydrolysis (EH) were performed in 30‐L reactors. The study showed that a steam pretreatment reactor should be larger than 2 L to yield acceptable results. Two pretreatment combinations were studied. In the H₂SO₄ case, the first pretreatment step was at 180°C for 10 min with 0.5% H₂SO₄ and the second step at 210°C for 2 min with 1% H₂SO₄. In the SO₂ case, first step was at 190°C for 2 min followed by a second step at 210°C for 5 min. The concentration of SO₂ was 3% in both steps. EH and SSF were performed on the whole slurry after the second pretreatment step to determine the yield of sugars and ethanol. The liquid after the first pretreatment step was also analyzed and fermented. When SSF and EH were performed at the same dry matter content and enzymatic activity, the ethanol yield in SSF exceeded the yield obtained with EH in both pretreatment cases, even when 100% yield in the fermentation step was assumed. Thus SSF is a better process if yield is the main priority. Comparison of the yields with the two acid catalysts showed higher yields with SO₂ in both SSF and EH. The overall ethanol yield following SSF of SO₂‐impregnated and pretreated wood reached 81% of the theoretical, that is, 357 liters per metric ton of dry raw material.     

Multi-methacrylated star-shaped,photocurable poly(methyl methacrylate) macromonomers via quasiliving ATRP with suppressed curing shrinkage

Novel, star-shaped multifunctional poly(methyl methacrylate) (PMMA) macromonomers with well-defined average number of pendant methacrylate groups were synthesized by copolymerizing MMA with 2-hydroxyethyl methacrylate (HEMA) via quasiliving ATRP with a tetrafunctional initiator in methanol at 10 °C, followed by methacrylation of the hydroxyl groups of the HEMA units. The resulting tailor-made poly(methyl methacrylate-co-2-methacryloylethyl methacrylate), P(MMA-co-MEMA), multifunctional macromonomers were used as cross-linking agents in photocuring of MMA, a solvent for its own polymer, and thus chemically homogeneous PMMA networks were formed in which the tetrafunctional initiator moiety provides inherent, additional branching points in the resulting cross-linked materials. This approach, even in the presence of relatively low amounts of macromonomers of ∼35–45%, provides sol-free products and up to ∼40% less polymerization shrinkage than that by curing of MMA with a conventional low molecular weight bifunctional methacrylate. These new, unique star-shaped PMMA macromonomers are potential cross-linkers in a variety of solvent-free applications where low curing shrinkage and high conversions are critical requirements, such as in several engineering materials, coatings, dental fillings and restorations, bone cements etc.     

2011年西安市采暖期燃煤灰分硫分含量现状研究

为了明确西安市采暖期间燃煤中灰分和全硫质量现状,为相关部门的管理和决策提供依据,选取具有典型性的两区两县送检的煤样进行了灰分和全硫测定。测定结果表明：郊县的用煤质量远低于城区的用煤质量;但城区的用煤质量形势也相当严峻,普煤中有近1／4的煤质灰分全硫双项不达标;型煤质量更加堪忧,有近1／3的型煤灰分不达标,1／2的型煤全硫含量超标。     

热重-红外光谱联机用于Cu/AC焙烧温度确定和焙烧过程分析

通过浸渍法制备载铜活性炭(Cu/AC),利用热重-红外光谱联机分析方法对Cu/AC前驱物Cu(NO3)2/AC进行分析,探索了前驱物制备Cu/AC在焙烧过程发生的变化,确定Cu/AC的最佳焙烧温度为700℃。     

超低挥发性有机化合物水性内墙涂料的研制

超低挥发性有机化合物水性内墙乳胶漆以其安全、环保等特点持续性地吸引业内的关注.此文叙述了不用成膜助剂制备环保型内墙乳胶漆,主要采取两种不同方式：低玻璃化转变温度（Tg）乳液结合高PVC（颜料体积浓度）;高Tg、低Tg两种乳液混拼,结果证明,上述两种方案均可以获得成膜良好的超低VOC水性内墙乳胶漆.