Formation of high molecular weight products from benzene during boundary lubrication

High molecular weight products were detected on the wear track of an iron disk at the end of a sliding friction and wear test using benzene as a lubricant. Size exclusion chromagography in conjunction with UV analysis gave evidence that the high molecular weight products are polyphenyl ether type substances. Organic electrochemistry was used to elucidate the possible surface reaction mechanisms

Analysis of a MIL-L-27502 lubricant from a gas-turbine engine test by size-exclusion chromatography

Size exclusion chromatography was used to determine the chemical degradation of MIL-L-27502 oil samples from a gas turbine engine test run at a bulk oil temperature of 216 C. Results revealed a progressive loss of primary ester and additive depletion and the formation of higher molecular weight products with time. The high molecular weight products absorbed strongly in the ultraviolet indicating the presence of chromophoric groups

Surface catalytic degradation study of two linear perfluoropolyalkylethers at 345 C

Thin-liquid-film degradation studies of two commercially available perfluoropolyalkylether fluids (PFAE) were performed at 345 C, in nitrogen and air atmospheres, on iron and 440 C stainless steel surfaces. It was found that one fluid degraded on both iron and 440 C stainless steel surfaces in an air atmosphere, whereas the other fluid did not degrade. Chemical analysis revealed that the test fluid degraded to lower molecular weight products and that the degradation was accompanied by the formation of a brownish deposit on both the iron and 440 C stainless steel surfaces. Surface analysis of the deposit revealed a susbstantial amount of iron oxide (Fe2O3). It was hypothesized that the fluid which degraded did so because of its acetal structure. The other fluid, lacking the acetal structure, did not degrade

Understanding brønsted-acid catalyzed monomolecular reactions of Alkanes in Zeolite Pores by combining insights from experiment and theory

Acidic zeolites are effective catalysts for the cracking of large hydrocarbon molecules into lower molecular weight products required for transportation fuels. However, the ways in which the zeolite structure affects the catalytic activity at BrOnsted protons are not fully understood. One way to characterize the influence of the zeolite structure on the catalysis is to study alkane cracking and dehydrogenation at very low conversion, conditions for which the kinetics are well defined. To understand the effects of zeolite structure on the measured rate coefficient (k(app)), it is necessary to identify the equilibrium constant for adsorption into the reactant state (Kads-H+) and the intrinsic rate coefficient of the reaction (k(int)) at reaction temperatures, since k(app) is proportional to the product of Kads-H+ and k(int). We show that Kads-H+ cannot be calculated from experimental adsorption data collected near ambient temperature, but can, however, be estimated accurately from configurational-bias Monte Carlo (CBMC) simulations. Using monomolecular cracking and dehydrogenation of C-3-C-6 alkanes as an example, we review recent efforts aimed at elucidating the influence of the acid site location and the zeolite framework structure on the observed values of k(app) and its components, Kads-H+ and k(int)

Development of a flameproof elastic elastomeric fiber

Various flexible polyurethane structures containing halogen were synthesized from polyesters derived from aliphatic or aromatic polyols and dibasic acids. Aliphatic halide structures could not be used because they are unstable at the required reaction temperatures, giving of hydrogen halide which hydrolyzes the ester linkages. In contract, halogen-containing aromatic polyols were stable and satisfactory products were made. The most promising composition, a brominated neopentyl glycol capped with toluene disocyanate, was used as a conventional diisocyanate, in conjunction with hydroxy-terminated polyethers or polyesters to form elastomeric urethanes containing about 10% bromine with weight. Products made in this manner will not burn in air, have an oxygen index value of about 25, and have tensile strength values of about 5,000 psi at 450% elongation. The most efficient additives for imparting flame retardancy to Spandex urethanes are aromatic halides and the most effective of these are the bromide compounds. Various levels of flame retardancy have been achieved depending on the levels of additives used

Use of Pd/activated carbon fiber catalyst to dehydrogenate cyclohexane

In this work, activated carbon fibers (ACFs) were prepared from polyacrylonitrile fibers, Pd catalyst was loaded onto the ACFs. The BET surface areas noted before activation were in the range of 120-140 m2/g. Activation of the fibers with carbon dioxide increased the surface areas of the fibers to about 150-190 m2/g. Diameters of metallic Pd particles loaded along the fibers ranged from 50 nm to 100 nm. The shape of the Pd particles was generally spherical albeit some non-spherical Pd particles were also noted. The catalytic activity of the Pd/ACF system in dehydrogenating cyclohexane at 350oC under liquid-phase conditions was investigated. Utilizing the Pd/ACF system in the micro-autoclave of a differential scanning calorimetric system was described for the liquid-phase catalytic dehydrogenation of cyclohexane. The DSC thermogram of the non-catalytic system yielded fewer endothermic events compared to the catalytic dehydrogenation of cyclohexane in the presence of Pd/ACF. The dehydrogenation of cyclohexane at 350oC was a first-order reaction with a rate constant, k = 3.5 x 10-4 s-1. GC-MS analyses of the products of catalytic dehydrogenation revealed a wide distribution of saturated and unsaturated hydrocarbons that were not present in the corresponding non-catalytic experiment. The presence of high molecular weight products could be explained by the recombination of carbon radicals during reaction

Mixed-metal calix[8]arene complexes: structure, and ring opening polymerisation studies

Reactions of différent combinations of group V alkoxides or tungsten oxyalkoxide salts with p-tert-butylcalix[8]areneH8 (L8H8) affords mixed-metal calix[8]arene systems. Intruiging molecular structures are formed and the systems are capable of the ring opening polymerisation of ϵ-caprolactone under N2, air, or as melts affording mostly low molecular weight products

Rancang Bangun Jig and Fixture untuk Proses Machining Balance Weight pada Mesin CNC Milling 3 Axis

Companies engaged in manufacturing one of them is CV Gaya Indah which has produced a variety of component products for industrial needs. Balance weight is one of the products in production, in the manufacture of this product there are several plans to produce quality product. In the manufacture of balance weight products there is a difficult drill position to machining and requires mass production. This machining process requires supporting tools namely jig and fixture. Jig and fixture are needed to speed up the machining time of balance weight products accurately according to standards. The stages of designing a jig and fixture include a list of requirements, product dimensions, and knowing the characteristics of the machine used for its production. This research uses the Ulrich method which made three design concepts with two types of jigs, namely jig drilling and jig milling. Calculation stage in selection of bolts to ensure the bolts can withstand the Balance Weight on the jig and fixture well. The results of analysis and design of jig and fixture balance weight for machining process on CNC Milling 3 Axis machine, produce the product within 18 minutes with testing that produces acceptable products according to standards

Protein engineering of Pseudomonas fluorescens peroxidase Dyp1B for oxidation of phenolic and polymeric lignin substrates

Directed evolution was applied to dye-decolourizing peroxidase Dyp1B from Pseudomonas fluorescens Pf-5, in order to enhance the activity for oxidation of phenolic and lignin substrates. Saturation mutagenesis was used to generate focused libraries at 7 active site residues in the vicinity of the heme cofactor, and the libraries were screened for activity towards 2,6-dichlorophenol. Mutants N193 L and H169 L were found to show 7–8 fold enhanced kcat/KM towards DCP, and replacements at Val205 and Ala209 also showed enhanced activity towards alkali Kraft lignin. Residues near the predicted Mn(II) binding site were also investigated by site-directed mutagenesis, and mutants S223 N and H127R showed 4-7-fold increased kcat/KM for Mn(II) oxidation. Mutant F128R also showed enhanced thermostability, compared to wild-type Dyp1B. Testing of mutants for low molecular weight product release from Protobind alkali lignin revealed that mutant H169 L showed enhanced product release, compared with WT enzyme, and the formation of three low molecular weight metabolites by this mutant was detected by reverse phase HPLC analysis

The effects of space radiation on a chemically modified graphite-epoxy composite material

The effects of the space environment on the engineering properties and chemistry of a chemically modified T300/934 graphite-epoxy composite system are characterized. The material was subjected to 1.0 x 10 to the 10th power rads of 1.0 MeV electron irradiation under vacuum to simulate 30 years in geosynchronous earth orbit. Monotonic tension tests were performed at room temperature (75 F/24 C) and elevated temperature (250 F/121 C) on 4-ply unidirectional laminates. From these tests, inplane engineering and strength properties (E sub 1, E sub 2, Nu sub 12, G sub 12, X sub T, Y sub T) were determined. Cyclic tests were also performed to characterize energy dissipation changes due to irradiation and elevated temperature. Large diameter graphite fibers were tested to determine the effects of radiation on their stiffness and strength. No significant changes were observed. Dynamic-mechanical analysis demonstrated that the glass transition temperature was reduced by 50 F(28 C) after irradiation. Thermomechanical analysis showed the occurrence of volatile products generated upon heating of the irradiated material. The chemical modification of the epoxy did not aid in producing a material which was more radiation resistant than the standard T300/934 graphite-epoxy system. Irradiation was found to cause crosslinking and chain scission in the polymer. The latter produced low molecular weight products which plasticize the material at elevated temperatures and cause apparent material stiffening at low stresses at room temperature