Studies on the effects of the enzymatic treatment on silk fine powder

In this study, the silk treated by steam explosion was pulverized into fine powder with a mean particle size of 1.829 μm, then the feasibility of the application of the protease treatment to produce finer and more uniform silk powder was investigated. The results indicated that after the enzymatic treatment, the mean diameter of the silk powder was reduced from 1.829 to 1.546 μm and the equivalent diameter distribution became more concentrated; thus, the uniformity of the particles was improved. The infrared spectra analysis demonstrated that the silk powder remained the β‐sheet crystalline structure. X‐ray diffraction analysis showed the crystallinity of the polished silk powder was very slightly strengthened. It was found that the treatment reduced some polar amino acid in the sericin; however, the composition of the kinds of the amino acids did not change. In addition, the hot water‐solubility and moisture regain of the polished silk powder declined very slightly. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 2967–2971, 2006     

粒化高炉矿渣微粉的生产和应用

1 粒化高炉矿渣的利用众所周知粒化高炉矿渣（以下简称矿渣）是高炉炼铁的副产品,经水淬急冷处理,其颜色呈白色、浅灰色或黑色等。我国水泥行业近50年来一直用其作混合材,生产多品种硅酸盐水泥。尤其是矿渣硅酸盐水泥（以下简称矿渣水泥）,其矿渣掺量可达20％～70％。但至今,全国每年仍有几千万吨矿渣处于低效利用状况,其原因主要有以下几方面。1.1关于矿渣质量的评价水泥厂通常根据矿渣的颜色,凭经验判别其易磨程度,且仅对矿渣进行化学全分析,根据GB/T203-94计算其质量系数M作等级判别依据（M=     

Spouting of fine powder from vertically vibrated bed

Experimental and numerical studies of spouting of powder from vertically vibrated bed are performed. The powder flows out vigorously through a side orifice of the vertically vibrated vessel in which the powder is contained, provided that the vibration acceleration is greater than the gravitational one. The mechanism of the efflux and the relationship between the efflux rate and the vibration condition are examined. The interstitial air pressure in the bed is measured and is compared to the numerical analysis considering the relative motion of the powder bed to the vibrated vessel and percolation air flow. The outflow behavior of powder is observed by using a high-speed video camera. The experimental and the numerical results show that the powder spouts out intermittently with periodic air outflow, which is generated in response to the change of the gap between the bed and the vessel base. Furthermore, it is found that the efflux rate of powder is in proportion to the generated air pressure and in inverse proportion to the vibration frequency.     

Production of fine staple fibers from gabbro

Translated from Steklo i Keramika, No. 3, pp. 6–7, March, 1989     

Kinetics of fine powder centrifugation

Sedimentation of polydispersed particles in a centrifugal field as applied to the process of fine powder hydroclassification is regarded as a random Markovian process. According to the analytical solution of the boundary problem by the Kolmogorov—Fokker—Planck equation the separation process quality index depends upon the particle porperties and the process conditions. The results of the calculation are compared with the experimental data on the classification of fine abrasive powders.     

废橡胶细胶粉的应用研究进展

综述了废橡胶制取的粒径在0.3 mm以下的细胶粉在橡胶材料、建材、橡塑共混材料等领域的应用研究进展。分析了细胶粉在这三方面的应用中存在的问题,并提出了建议。     

Effect of plasma treatment of silk fibroin powder on the properties of silk fibroin powder/polyurethane blend film

In this study, silk fibroin powder was treated by dielectric barrier discharge (DBD) plasma. The objective is to improve the performance of the silk fibroin powder/polyurethane (PU) blend film used in biomechanical field. The scanning electron microscope (SEM) showed that the plasma‐treated powder was broken into small particles and the film from the treated powder became homogeneous and dense. Fourier transform infrared spectroscopy (FTIR) revealed that the hydrophobic groups in silk fibroin powder were oxidized during plasma treatment. Little change in chemical composition was found on the surface of the blend film from plasma‐treated powder. The fracture strain of the blend film from plasma‐treated powder was remarkably raised, whereas its tensile strength was influenced significantly by the plasma treatment conditions. The wet‐out time of the plasma‐treated powder/PU film was shortened considerably. This indicates the improved hydrophilicity of the blend film. In addition, the decreased values of water vapor permeability suggested that the structure of the blend film became dense. This might result from the strong interfacial adhesion between plasma‐treated powder and PU. POLYM. ENG. SCI., 50:1705–1712, 2010. © 2010 Society of Plastics Engineers     

Production of silk sericin/silk fibroin blend nanofibers

Silk sericin (SS)/silk fibroin (SF) blend nanofibers have been produced by electrospinning in a binary SS/SF trifluoroacetic acid (TFA) solution system, which was prepared by mixing 20 wt.% SS TFA solution and 10 wt.% SF TFA solution to give different compositions. The diameters of the SS/SF nanofibers ranged from 33 to 837 nm, and they showed a round cross section. The surface of the SS/SF nanofibers was smooth, and the fibers possessed a bead-free structure. The average diameters of the SS/SF (75/25, 50/50, and 25/75) blend nanofibers were much thicker than that of SS and SF nanofibers. The SS/SF (100/0, 75/25, and 50/50) blend nanofibers were easily dissolved in water, while the SS/SF (25/75 and 0/100) blend nanofibers could not be completely dissolved in water. The SS/SF blend nanofibers could not be completely dissolved in methanol. The SS/SF blend nanofibers were characterized by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry, and differential thermal analysis. FTIR showed that the SS/SF blend nanofibers possessed a random coil conformation and ß-sheet structure.     

化妆品用超细结晶蚕丝粉末的制备及表征

用质量分数为85%的磷酸催化水解桑蚕茧,茧与磷酸的质量体积比为1∶4时,在100℃条件下反应,可制得平均粒径为250 nm的结晶性丝粉,收率达70%以上.并对样品进行了扫描电镜、示差热分析、X-射线粉末衍射等表征分析.     

超细蚕丝粉制备方法研究

简要介绍了蚕丝粉的制备原理、工艺过程和工艺特点 ,以及产品的性能 (粒度及粒度分布 )和氨基酸成分 ,并就应用前景及应用原理作了概略的讨论。     

焦粉活性炭体系导电涂料的制备

研制了一种以焦粉活性炭为导电填料、酚醛清漆为基料的导电涂料。采用单因素实验方法确定偶联剂用量、球磨时间、焦粉活性炭与酚醛清漆质量比与体积电阻率的关系。偶联剂用量为体系总质量的1.5%左右,球磨时间为7h,焦粉活性炭与酚醛清漆的质量比为0.6时,涂料的导电性能最佳,ρν约为14.4Ω.cm。     

化学沉淀-热分解法制备超细氧化镍粉的研究

用化学沉淀-热分解法制备超细氧化镍粉,以氯化镍为原料,碳酸氢铵为沉淀剂,在沉淀反应和洗涤过程中都引入了超声场.用XRD,激光粒度仪,SEM分别对产物进行表征.实验结果表明,在前驱体的制备扣洗涤过程中引入超声场可以有效地解决粒度分布范围宽,颗粒不均匀,团聚明显,微粒形态不规则的问题.在有超声作用、80℃恒温水浴和磁力搅拌作用下,采用并加加料方式制备出了晶粒度在5～10nm,颗粒径在2～3μm,颗粒均匀,形态规则的超细氧化镍粉.     

Classification of ultra fine powder by a new pneumatic type classifier

Recently, there are great requirements for ultra fine powder in fields that use advanced materials, for example, electric parts in Information Technology (IT) industry. Especially, the request for the diameter control of ultra fine powder is increasing. Pneumatic type ultra fine powder separator, classifier, is one of the equipment which meet this request. But there is no clarified study on the flow condition that realizes high performance. In this study, a new pneumatic type ultra fine classifier is proposed and the relation between the performance and the flow condition is investigated by flow visualization with the tuft grid and oil dot methods and the measurement of gas velocity.Based on the results, it was known that the new classifier has a large swirling flow velocity which is able to classify ultra fine particles accurately.     

微波辐射-KOH活化兰炭粉制备活性炭

研究了以兰炭粉为原料,KOH为活化剂,采用微波辐射法制备活性炭的可行性。探讨了微波功率、碱炭质量比和活化时间对活性炭吸附性能的影响。同时采用美国ASAP-2020吸附仪测定了所制备活性炭的N2吸附脱附等温线和孔径分布,采用红外光谱分析了样品的表面官能团。结果表明:微波功率为700 W,碱炭质量比为3,活化时间为15 min工艺条件下制得的活性炭碘吸附值为694.5 mg/g,比表面积为513.62 m2/g,总孔容为0.510 3 cm3/g,平均孔径为3.973 8 nm,该活性炭为中孔型。以兰炭粉为原料,传统加热和微波加热制备的活性炭红外光谱图其峰形基本一致,只是峰强不同。     

用加热磷酸生产粉状磷酸一铵

红磷分公司磷铵厂采用低压蒸汽加热原料磷酸生产粉状磷酸一铵,介绍磷酸加热工艺流程及设备,分析了磷酸加热对中和反应及产品的影响。实践表明:磷酸加热可有效提高水分蒸发量、反应温度及料浆流动性,对控制产品养分和保证产品颜色也有一定作用。     

超细粉体分级技术研究进展

较详细介绍了分级原理和评价标准,对超细粉体分级技术中的干法分级及其典型设备作了较全面的介绍,对分级技术的现状进行了分析,并提出一些建议     

Preparation and sintering of fine molybdenum powder

The reduction conditions necessary to prepare fine molybdenum powders from ammonium dimolybdate (ADM) powder were studied in the laboratory. Milling of the ADM, the use of low reduction temperatures, a low bed depth for reduction of ADM to MoO₂ powder, and a subsequent deeper bed depth for reduction of MoO₂ to Mo yielded finer powders. In laboratory studies using sintering times of 2, 5 and 8 h in vacuum, the finer powders sintered to equivalent densities in 3 h shorter sintering times than coarser powders.     

Ultra-fine silk powder preparation through rotary and ball milling

Three commercial silk varieties, namely mulberry, muga and eri, were used to prepare ultra-fine silk particles. Degummed silk fibres were chopped into short snippets and then pulverised using rotary and planetary ball milling. The effects of degree of degumming, size of milling media, water and lubricant on particle refinement were studied. Before milling, single fibre strength tests were conducted on silk fibres degummed under different conditions. The results indicate that while reducing fibre strength via harsh degumming could cut milling time drastically, too severe a reduction in fibre strength is actually detrimental to achievable minimum particle size due to increased particle aggregation. Water played an important role in affecting the performance of ball milling. With the milling processes used in this study, a volume based median particle size (d(0.5)) of around 200 nm was achieved, which is much smaller than previously reported results. To achieve a similar particle size, mulberry silk required more milling time, even though the overall milling behaviour was quite similar for the three silk varieties examined. SEM observations revealed axial spitting and fragmentation of micro and nanofibrillar architecture of silk fibres due to milling. Unlike ball milling, which produced particles with variable shapes, rotary milled particles remained fibrous through the size reduction process.     

二氧化硅微细粉体纯化工艺的研究

本试验通过擦洗、脱泥、调浆、浮选等工序可将二氧化硅微细粉体中ＳＯ２含量从９９．１％提高到９９．７７％左右,相应地Ｆｅ２Ｏ３含量０．０８１％下降到０．０１４％～０．０２３％,产率为３３％～８５％,表明该工艺能显著改善二氧化硅微细粉体的品质。     

二氧化硅微粉在轮胎配方中的应用

对二氧化硅微粉与其它无机填料进行比较试验,并在轮胎胎面胶,胎体胶配方中使用二氧化硅微粉进行半成吕,成品应用试验,结果表明,二氧化硅微粉作为无机填料具有较好的补强性能,完全可以满足轮胎胎面和胎体的性能要求,而且可以低成本,改善生态环境。