Phosphoric Acid Esters Research Articles

Shear characteristics of a boundary film for a paper-based wet friction material: friction and real contact area measurement

A paper-based wet friction material lubricated with automatic transmission fluids (ATFs) produces plateau and positive slope regions in the friction–sliding velocity diagram. This feature observed at less than 1 mm/s of sliding velocity is discussed in this paper. The relationship between the friction and contact pressures of less than 5 MPa was determined by a reciprocating friction test rig lubricated with mineral oil including phosphoric acid ester, one of the additives for ATFs. The real contact area for dry condition was also determined by optical interferometry. The consistency of the real contact pressure dependency of the shear strength of the boundary film was indicated at pressures of less than 1 GPa obtained by steel-on-steel boundary friction (oiliness) test. This suggests that the generation of the positive slope region is due to thin film lubrication. To the plateau region, possibility of application of the phase transition model is considered.

STUDIES ON THE APPLICATION OF ALKYL PHOSPHORIC ACID ESTER IN THE FLOTATION OF WOLFRAMITE

The application of alkyl phosphoric acid ester for the flotation of wolframite was investigated. The studies include flotation of pure wolframite as a function of pulp pH, surfactant concentration, and particle size. The response contours were explained on the basis of solution properties of alkyl phosphoric acid ester. The performance of alkyl phosphoric acid collector has been compared with other commercially used wolframite flotation reagents. The efficacy of the reagent was also tested using a low-grade quartz vein type tungsten ore (WO3 0.2%) having wolframite as the chief tungsten-bearing mineral. Different parameters that influence the flotation selectivity (pH, collector and dispersant dosage, kinetics) were investigated in the bench scale studies. A continuous flotation test with a reagent regime of alkyl phosphoric acid collector-sodium silicofluoride modifier—amyl alcohol frother—gave a float product analyzing WO3 8% with 68% overall recovery after multistage flotation. The tungsten metal values from this cleaner float can be extracted efficiently using established hydrometallurgical methods.

Thermochemistry of heteroatomic compounds

The enthalpies of combustion (ΔH comb) of 13 primary, secondary, and tertiary alkylphoshines in the condensed state were calculated using the equation ΔH comb = −860.7 − 107.0N, where N is the number of valent (bond-forming) electrons. This equation can be used for the calculation of enthalpies of combustion and formation of phosphoric acid esters.

Aggregation Behavior of Sodium Mono-n-Dodecyl Phosphate Surfactant in Aqueous Media, and Function in Catalytic Activity. I. Multi-Step Aggregates Formation and Catalytic Activity for Hydrolysis of p-Nitrophenyl Acetate in Aqueous Solution

Aggregation behavior of sodium salt of mono-n-dodecyl phosphoric acid ester i.e. a species of mono-alkyl phosphate (MAP) surfactants, in pure water was investigated as a function of surfactant concentration (CS) by means of surface tension (γ), electroconductivity (measuring both specific (κ) and molar (Λ) conductivities), pH and UV-Vis spectra measurements. The Krafft temperature was determined as 40°C by observing the change of κ with raised temperature. Although the curve of γ vs. log CS plot gave only one break which corresponds to critical micellization concentration(CMC) in common theory, different relations of κ vs. CS, Λ vs. √CS, or κ vs. log CS, and pH vs. CS resulted in several breaks suggesting the occurrence of various transitions of aggregates or micelles over the concentration range not only above, but also below CMC. The CMC determined by surface tension measurement was referred to as the first CMC (CMC1). The critical concentrations of the transitions observed by various methods were termed as CACi (i=1,2,3) for three-step aggregate formation below CMC1 and as CMCj (j=1-5) for five-step transitions in micellar form. From the temperature study on CACi and CMCj, the estimated standard Gibbs energy changes were estimated, which showed us that the primary driving force of aggregate/micelle formation at any step comes from the entropy term, since the energy term (enthalpy) in this case was found to be positive. This supports our interpretation that the aggregates/micelles are mainly composed of hydrolyzed (protonated) mono-dodecyl phosphate molecules so that they behave as if they were nonionic surfactant micelles. A light scattering measurement verified the existence of aggregates formed below CMC. The experiment of catalytic activity assay revealed that SMDP aggregates formed in the low concentration range (ten times lower than CMC1) were found to act as catalysts for the hydrolysis reaction of p-nitrophenyl acetate (pNPA).

Rejection mechanisms of plastic additives and natural hormones in drinking water treated by nanofiltration

Rejection mechanism of nanofiltration (NF) membrane for organic solutes (including alkyl phenol, bisphenol A, phthalate acid esters, phosphoric acid esters, other plastic additives, and natural hormones like 17β estradiol, etc) was examined. The experiments indicated almost complete removal of these solutes by the tight NF membranes, while the rejection obtained by the loose membranes was dependent on solute species. Compounds with flat-shaped structure like 2-H-benzothiazol and dimethyl phthalate were more permeable than other target solutes within the same molecular size range. Of the four methods of size determination used, there was no significant difference in the accuracy of prediction of rejection from the solute sizes. The size configurations of molecules have been identified to greatly influence the permeation or retention, yet the size parameter was thought to be incomplete as a single parameter in describing rejection of organic solutes. The logarithm of octanol-water partitioning coefficients of solutes appears not to be an effective parameter in modelling rejections as its contribution was only slight or minor. We obtained better correlations with structural configuration of molecules (by molecular width and length) and polarity of the molecules.

The Behavior of Zinc Metal in Alkaline Solution Containing Organic Inhibitors : II. Identification of Surface Films Formed on Zinc

Surface analysis obtained with the use of high resolution scanning electron microscopy and in situ atomic force microscopy revealed different morphology characteristics developed at the zinc surface in the presence of polyoxyethylene backbone based organic inhibitors. Fourier transform Infrared spectroscopy data show that polyoxyethylene alkyl phosphate ester acid [GAFAC RA 600] adsorbed on the zinc surface via the phosphonium ion head, while polyethylene glycol is adsorbed on the zinc surface via the alkoxide anion head. It was also established that the preferred organic inhibitor should include a linear polyoxyethylene chain. © 2003 The Electrochemical Society. All rights reserved.

The Behavior of Zinc Metal in Alkaline Solution Containing Organic Inhibitors: I. Electrochemical Studies of Zinc

The electrochemical behavior of zinc in strong alkaline solutions containing 8.5 M of potassium hydroxide (KOH) and polymeric organic inhibitors was evaluated. The concentrations of the organic inhibitors studies were in the range of 400-4000 ppm and included polyethylene glycol (PEG), with a molecular weight of 300-900, and polyoxyethylene alkyl phosphate ester acid form (GAFAC RA600). The electrochemical studies included potentiodynamic and potentiostatic polarizations. The inhibition properties of PEG 600, in the strong alkaline solution, are by far much more efficient than the inhibition capability of the other polymers. The studies also indicate that evaluation of the inhibitors should be conducted as a function of storage time. The evaluation of other polymeric compounds established that the polymer must contain a linear polyoxyethylene backbone with a chain length of ∼10 units with an optimal polymer concentration in the range of 800-2000 ppm. The described electrochemical methods are suggested as a rapid tool in the evaluation of organic polymers inhibitors, offering a precise determination of the optimal concentration in the alkaline media. © 2003 The Electrochemical Society. All rights reserved.

Supported liquid membrane separation of amine and amino acid derivatives with chiral esters of phosphoric acids as carriers

Studies on the possible use of phosphate and phosphonate esters bearing chiral menthol or nopol moieties as carriers for the transport of amines, amino acids, and amino acid esters through supported liquid membranes (SLM) are presented. Additionally, the enantioselectivity of the SLM transport of alkyl esters of aromatic amino acids and a non-protein amino acid was also evaluated. It could be concluded that the extent of transport strongly depends on the hydrophobicity of the amino compound. Moreover, the carrier structure also influences the transport of those compounds through SLM: chiral phosphate and phosphonate esters appear to be poor or moderate carriers for enantioselective SLM transport of amino acids and their esters. The transport efficiency and selectivity is strongly dependent on the structure of both the transported compounds and the carrier. However, no meaningful relationship exists between these structural features and transportation or enantioselectivity.

Nucleating Efficiency of Organic Phosphates in Polypropylene

Organic phosphates used as nucleating agents can remarkably promote the stiffness and crystallization rate of polypropylene homopolymer and ethylene–propylene copolymer. In this article, the nucleating activity of 2,2′-methylene-bis(4,6-di-tert-butylphenyl) phosphoric acid and its derivatives for isotactic polypropylene (iPP) were investigated with a differential scanning calorimeter (DSC) and polarized light microscope (PLM), and their influence on mechanical properties of polypropylene was also studied. The results showed that the sodium salt (NA7) and the glyceride ester (NA8) of the organic phosphoric acid were of high nucleating efficiency. If 0.4 wt% of NA7 or NA8 was added to PP, the crystallization peak temperature of PP was raised 15°C or 11°C, respectively, the amount of crystallinity was increased by 3 to 6%, and the crystallization rate was enhanced significantly. The nucleating activity is thermally stable when the mixture of iPP and a nucleating agent was melted and crystallized repeatedly in the DSC. The nucleating agents mentioned above could increase the modulus of the polymer by 20 to about 30% and could increase the flexural strength by 10 to about 20%. However, a number of other organic phosphates tested have little nucleating effect.

Surfactant Properties of Monoalkyl Ethanolamine Phosphate Esters

Monolauryl and monostearyl phosphoric acid esters were synthesized by phosphorylation of the corresponding long chain fatty alcohols which were subsequently neutralized with mono-, di- and tri-ethanolamines. Monoalkyl nature of phosphate derivatives was ascertained by evaluating phosphorus contents. All the phosphate derivatives displayed appreciable lowering of surface tension of water and the monoethanolamine compounds, in particular, showed lower CMC values compared to the conventional anionic surfactant, linear alkyl bezene sodium sulphonate. Monoethanolamine derivatives of lauryl and stearyl esters of phosphoric acid exhibited lower water solubility compared to diethanolamine and triethanolamine derivatives. Foam characteristics of all the compounds were, in general, poor. Monolauryl diethanolamine phosphate ester indicated superior wetting power.

Development of protein microarray technology to monitor biomarkers of rheumatoid arthritis disease.

Most biological processes are mediated by complex networks of molecular interactions involving proteins. The analysis of protein expression in biological samples is especially important in the identification and monitoring of biomarkers for disease progression and therapeutic endpoints. In this paper, the development of a protein microarray format for multiplexed quantitative analysis of several potential markers for rheumatoid arthritis (RA) is described. Development of a high-performance protein microarray system depends on several key parameters such as surface chemistry, capture agents, immobilization technology, and methods used for signal detection and quantification. Several technical possibilities were investigated and compared: poly-L-lysine versus self-assembled monolayer of octadecyl phosphoric acid ester for surface chemistries; noncontact piezoelectric versus contact printing technology for antibody deposition; CCD camera capture versus fluorescent scanning for image detection; and the concentration of coating antibody. On the basis of reproducibility, signal-to-noise ratio, and sensitivity we have selected self-assembled monolayer, noncontact piezoelectric printer, and high-read-out fluorescence scanning for our microarray format. This format was used to perform multiplexed quantitative analysis of several potential markers of disease progression of rheumatoid arthritis: IL-1beta, IL-6, IL-8, MCP-1, and SAA. Some assays, such as MCP-1, provided a working range that covered physiologically relevant concentrations. Other assays, such as IL-6 and SAA, lacked sensitivity or were too sensitive for measuring biological concentrations, respectively. The results described demonstrate the applicability of protein microarrays to monitor RA markers; however, sandwich assay methodologies need to be further optimized to measure the appropriate biological ranges of these markers on one chip.

Electrochemical and surface studies of zinc in alkaline solutions containing organic corrosion inhibitors

The electrochemical behavior of zinc in strong alkaline solutions containing 8.5 M of potassium hydroxide (KOH) and polymeric organic inhibitors was evaluated. The concentrations of the organic inhibitors studies were in the range of 400–4000 ppm and included polyethylene glycol (PEG), with a molecular weight of 600, and polyoxyethylen alkyl phosphate ester acid form (GAFAC RA600). The electrochemical studies included anodic, cathodic, and linear polarization along with potentiostatic studies. It was found that the inhibition properties of PEG, in the strong alkaline solution, are by far much more efficient than the inhibition capability of GAFAC RA600. Surface analysis obtained with the use of high resolution scanning electron microscopy (HRSEM) revealed different morphology characteristic developed at the zinc surface in the presence of the two inhibitors. A methodology employing electrochemical tests is proposed to quickly and conveniently evaluate inhibitors for Zn in alkaline media.

Adamantane-like aluminum amide-phosphate from alumazene.

A dealkylsilylation reaction between alumazene [2,6-(i-Pr)(2)C(6)H(3)NAlMe](3) (1) and tris(trimethylsilyl) ester of phosphoric acid (2) in a 1:3 molar ratio provides the heteroadamantane molecule (MeAl)[2,6-(i-Pr)(2)C(6)H(3)N](3)[Al[OP(OSiMe(3))(3)]](2)(O(3)POSiMe(3)) (3). Compound 3 was characterized by analytical and spectroscopic methods, and its molecular structure was established by a single-crystal X-ray diffraction experiment. Moreover, trialkyl and triaryl phosphates and dialkyl phosphonates react with 1 at elevated temperature to afford an intractable mixture of products. The reaction of phosphonic acids with 1 proceeds under decomposition to yield 2,6-diisopropylaniline and aluminophosphonates.

Reactive dispersions for corrosion inhibition

Several concepts have been developed for the improvement of adhesion promotion and corrosion inhibition of reactive metal surfaces, like aluminum. The aim of these studies was to replace the present technical procedure for pretreatment of aluminum surfaces with chromium acid. Therefore, the adsorption and organization process of mono- and bifunctional alkyl phosphonic acids and mono alkyl phosphoric acid esters has been investigated. The properties of the adsorbed SAM's were confirmed by industrial linked adhesion and corrosion tests. By functionalization of the terminal position with thiophene, molecules are prepared which can graft conducting polythiophene layers via surface polymerisation on silicon/metal substrates. Also polymeric nano-particles with phosphoric acid groups form thin and smooth well-packed films on aluminum surfaces. Stable core-shell polypyrrole (PPy) dispersions were prepared by using polystyrene (PST) or poly (styrene-co-butyl acrylate) (PST-co-BuA) as the core, and polypyrrole as the shell.

Alkyl-chain selective analysis of phosphoric acid esters with non-aqueous capillary electrophoresis

Non-Aqueous capillary electrophoresis has proved to be an efficient technique for the analysis of phosphoric acid esters. Using an electrolyte based on N-methylformamide, short chain phosphoric acid esters and water insoluble long chain phosphoric acid esters were analyzed simultaneously. The background electrolyte consisted of 15 mM ammonium anthraquinonesulfonate as background chromophore for indirect detection, 10 mM triethylamine, and 0.001% polybrene. It allowed determination of the alkyl chain length of the analytes, and distinction between ethoxylated and non-ethoxylated phosphoric acid esters even in more complex mixtures. The method enabled fast separation within 8 min after uncomplicated sample preparation.

Characteristics of the electroosmotic flow of electrolyte systems for nonaqueous capillary electrophoresis.

Nonaqueous capillary electrophoresis (NACE) is a powerful tool for the analysis of surface-active substances, which represent a broad class of analytes containing cationic and anionic species, such as surfactants, phosphoric acid esters, and amines. In order to conduct an efficient method development in NACE, the influence of the electrolyte composition on the electroosmotic flow (EOF) of organic separation systems was systematically investigated. Background electrolytes and background chromophores appropriate for direct and indirect UV-detection were considered, as the majority of surface-active substances do not absorb UV-light. It was found that theoretical models developed to describe the EOF in aqueous electrolyte systems are insufficient for organic electrolyte systems. Experimental data on electroosmosis in a variety of organic solvents and mixtures of methanol and acetonitrile applying different background chromophores and basic or acidic additives are given. Differences between them are discussed with relation to the physicochemical properties of the organic solvents.

Effects of epithalon on activities gastrointestinal enzymes in young and old rats.

Peroral administration of Epithalon (Ala-Glu-Asp-Gly) to male and female Wistar rats aging 3 and 11 months changed activity of enzymes hydrolyzing carbohydrates, proteins, and phosphoric acid esters in various portions of the gastrointestinal tract. The most pronounced activation of enzymes was observed in 11-month-old animals. This effect diminished the differences in enzyme activities between young and old rats (compared to untreated animals). Our results indicate that Epithalon modulates activity of gastrointestinal enzymes during aging.

Lubrication of surface oxidized Co–Cr thin films by phosphoric and phosphorous acid esters

Phosphoric and phosphorous acid esters have been applied to surface oxidized Co–Cr thin films, and their lubrication performances are investigated. Tricresyl phosphate, phosphoric and phosphorous acid esters with long alkyl chains are found to be very effective in reducing friction and wear of thin films. Such excellent lubrication performances could be attributed to their strong adsorption to the oxide surfaces and large cohesive energy between the lubricant molecules. These results are discussed in detail.

Nonaqueous gel electrolytes doped with phosphoric acid esters

Highly conducting anhydrous gels doped with phosphoric acid esters have been obtained by entrapping ester solutions in polar aprotic solvents into the poly(vinylidene fluoride) or poly(methyl methacrylate) matrices. The dependence of the physical–chemical properties of these materials on the type and concentration of proton donor, as well as solvent used, are described. It is found that use of propylene carbonate- N, N-dimethyl formamide solvent mixture allows to obtain transparent gels in a wide (5–40 mass%) ester concentration range. Conductivities exceeding 5×10 −4 S cm −1 (PVdF-based systems) and 1×10 −3 S cm −1 (PMMA-based gels) are reported. The mechanism of proton conduction is discussed on the basis of impedance spectroscopy and PFG NMR experiments.

Electrochemical synthesis of organophosphorus compounds with PO, PN and PC bonds from white phosphorus

The conditions of electrochemical oxidation of white phosphorus are studied, and direct electrochemical methods for the synthesis of esters of phosphoric, phosphorous and phosphonic acids, amidoesters and trialkyl and triaryl phosphines from white phosphorus were elaborated. Equipment allowing the processes to be carried out continuously and under fire-safe conditions using synthesis of triethyl phosphate was tested as an example. The proposed processes are suitable for industrial technology.