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Optical Coatings for High Power Lasers
Published in Marvin J. Weber, and TECHNOLOGY, 2020
Mark R. Kozlowski, Robert Chow, Ian M. Thomas
Low-absorption coatings require compositionally pure starting materials and clean vacuum chambers. The starting material should have a purity of at least 99.9%. An e-gun is used because the material evaporates from a “crucible” of its own material and purity. The vacuum deposition process should provide residual gas pressures at least two orders of magnitude lower than the partial pressure of the evaporant molecule during a deposition run. To minimize the background pressures the vacuum chamber should be made of low out-gassing-rate materials such as certain grades of Al, stainless steel, O-ring seals, and ceramics. The high-vacuum pumping stacks are usually either diffusion pumps with cryogenic baffling, or turbomolecular pumps with cryogenic pumps. Both systems minimize the backstreaming of pump oils.
Alkylated Aromatics
Published in Leslie R. Rudnick, Synthetics, Mineral Oils, and Bio-Based Lubricants, 2020
Shuji Luo, Suzzy C. Ho, Margaret M. Wu
Table 8.16 compares the typical viscometric properties of the heavy fluids produced in LAB or BAB processes with other common commercial synthetic base stocks. The LAB-based fluids usually have a VI greater than 100, as well as very low pour points and very good low-temperature viscosities. These properties are slightly inferior to a typical PAO or dibasic esters. They can be improved by careful choice of starting material and reaction conditions [49]. The BAB-based fluids usually have very poor VI and poor low-temperature viscosities.
Exploring the Potential of 3D Printing of the Spare Parts Supply Chain in the Maritime Industry
Published in Adam Weintrit, Tomasz Neumann, Safety of Sea Transportation, 2017
The raw materials for the process are: polymers, metals, ceramics, composites, and biological materials. The starting materials could be liquid, filament/paste, powder, or solid sheet. Currently, the most common metallic materials are steels (tool steel and stainless), pure titanium and titanium alloys, aluminum casting alloys, nickel-based super alloys, cobalt-chromium alloys, gold, and silver (Frazier, 2014).
The product of interaction of elemental sulfur and dimethylphosphate 1,3-dimethylimidazolium is a new green initiator of formaldehyde polymerization
Published in Green Chemistry Letters and Reviews, 2021
Natalia Tarasova, Alexey Zanin, Efrem Krivoborodov, Mikhail Motyakin, Irina Levina, Valerie Dyatlov, Ilya Toropygin, Victor Dyakonov, Yaroslav Mezhuev
Polyformaldehyde is a large-capacity commercially produced structural thermoplastics, the volume of production of which is constantly increasing (1). Therefore, the development of new approaches to the synthesis of polyformaldehyde is a task that must be solved in accordance with the principles of green chemistry (2). This paper describes a new system that initiates the polymerization of formaldehyde at a high rate at room temperature, which allows to achieve absolute atomic economy, does not create a load on the environment, and uses sulfur, which is common in nature, and the ionic liquid 1,3-dimethylimidazolium dimethylphosphate, as the starting materials. This approach is promising for initiating the polymerization of not only formaldehyde but also a number of other electron-deficient monomers, especially in cases where the synthesis of polymers creates a significant load on the environment. Elemental sulfur occurs in nature, but recently the volume of its production by the oil refining industry exceeds demand and leads to the accumulation of sulfur dumps (3, 4). Therefore, the development of new approaches to include elemental sulfur in technologies and processes is of interest for increasing possibilities of chemical synthetic methods with ecological and economic benefits (4).
A convenient four-component reaction for the synthesis of dithiocarbamates starting from naphthols in water
Published in Journal of Sulfur Chemistry, 2020
Maryam Khalili Foumeshi, Rohollah Haghi, Petr Beier, Azim Ziyaei Halimehjani
In conclusion, efficient one-pot four-component reaction for the synthesis of 1-(dithiocarbamatomethyl)-2-naphthols and 2-(dithiocarbamatomethyl)-1-naphthols from commercially available starting materials including 2-naphthols, secondary amines, CS2 and formaldehyde was developed. Mild reaction conditions, using water as a solvent, broad substrate range and good to excellent yields of products are the main advantages of this protocol, which makes this reaction a powerful and attractive strategy in green chemistry. Furthermore, a wide range of mono and bis(dithiocarbamates) containing naphthol moiety on the sulfur atom were synthesized which might be useful substrates for biological studies. Finally, the presence of acidic aromatic hydroxyl groups in the target compounds is likely to increase solubility of these compounds in mildly basic solutions.
Preparation and properties of a novel type of tannin-based wood adhesive
Published in The Journal of Adhesion, 2022
Xinyi Chen, Antonio Pizzi, Emmanuel Fredon, Christine Gerardin, Jinxing Li, Xiaojian Zhou, Guanben Du
The topic of environmental and eco-friendly wood adhesive is now one of the hottest subject and an unavoidable one in the wood industry.[1] Nowadays, formaldehyde-based wood adhesives are so widely applied due to their low cost, short curing time and strong adhesion.[2,3] Formaldehyde-based adhesives are account for almost 90% of totally wood adhesives industry.[3] Nevertheless, traditional synthetic wood adhesives present two main drawbacks, these being their toxic starting materials (i.e. formaldehyde and phenol) and formaldehyde-emission during their use and for long time afterward. Therefore, these drawbacks have created a demand for adhesives prepared from non-toxic and inexpensive materials to replace them.