SELECTION OF POUR POINT DEPRESSANTS FOR TODAYS ENGINE OILS INCLUDING AGING IN THE PRESENCE OF BIODIESEL BY CEC L-105

All mineral derived base stocks used in lubricants contain waxy hydrocarbons that come out of solution when temperature decreases. They can form a three-dimensional wax crystal network that can totally immobilise the oil. In formulated engine oils some additives have a “waxy” or crystalline structure and further contribute to the formation of a crystal network that impairs oil flow. Waxiness is evidenced at low temperature by higher pour-point, yield stress and viscosity compared to a wax free oil. Inadequate oil flow to critical parts of the equipment may result in costly failures. The function of Pour-Point Depressant (PPD) is given in the name. They depress pour-point by inhibiting the waxy structures that form in mineral oil at low temperature. But for modern engine oils pour-point has little relevance and isn’t included in modern international engine oil standards. Industry experience over the decades has replaced pour-point by other more valid assessments of an engine oil’s suitability at low temperature. In particular low temperature pumpability by Mini Rotary Viscometer (MRV) due to its inclusion in SAE J300 specification is the primary test. In some cases this is now required on used oil, and most recently in Europe on oil oxidised in the presence of biodiesel by CEC-L-105-12. However PPDs exist or have been developed which are effective in these evolved low temperature requirements of engine oils. In this paper we show that PPDs are available which are effective against this latest European CEC L-105 requirement, although extra consideration must be given to their selection. We also show that multiple low temperature requirements tend to narrow the choice of acceptable PPDs, and the choice of PPD can be strongly influenced by the presence of other additives in addition to the mineral oil. These combined with the extra requirement for CEC L-105 has made PPD selection more difficult, but based on our work reported here this new challenge can be met by correct PPD selection

SELECTION OF POUR POINT DEPRESSANTS FOR TODAYS ENGINE OILS INCLUDING AGING IN THE PRESENCE OF BIODIESEL BY CEC L-105

All mineral derived base stocks used in lubricants contain waxy hydrocarbons that come out of solution when temperature decreases. They can form a three-dimensional wax crystal network that can totally immobilise the oil. In formulated engine oils some additives have a “waxy” or crystalline structure and further contribute to the formation of a crystal network that impairs oil flow. Waxiness is evidenced at low temperature by higher pour-point, yield stress and viscosity compared to a wax free oil. Inadequate oil flow to critical parts of the equipment may result in costly failures. The function of Pour-Point Depressant (PPD) is given in the name. They depress pour-point by inhibiting the waxy structures that form in mineral oil at low temperature. But for modern engine oils pour-point has little relevance and isn’t included in modern international engine oil standards. Industry experience over the decades has replaced pour-point by other more valid assessments of an engine oil’s suitability at low temperature. In particular low temperature pumpability by Mini Rotary Viscometer (MRV) due to its inclusion in SAE J300 specification is the primary test. In some cases this is now required on used oil, and most recently in Europe on oil oxidised in the presence of biodiesel by CEC-L-105-12. However PPDs exist or have been developed which are effective in these evolved low temperature requirements of engine oils. In this paper we show that PPDs are available which are effective against this latest European CEC L-105 requirement, although extra consideration must be given to their selection. We also show that multiple low temperature requirements tend to narrow the choice of acceptable PPDs, and the choice of PPD can be strongly influenced by the presence of other additives in addition to the mineral oil. These combined with the extra requirement for CEC L-105 has made PPD selection more difficult, but based on our work reported here this new challenge can be met by correct PPD selection

Immobilization of Methyl Orange and Methylene Blue within the Matrix of Charge-Imbalanced Amphoteric Nanogels and Study of Dye Release Kinetics as a Function of Temperature and Ionic Strength

Cross-linked polyampholyte nanogels consisting of neutral N-isopropylacrylamide (NIPAM), negatively charged sodium salt of 2-acrylamido-2-methylpropanesulfonate (AMPS), and positively charged (3-acrylamidopropyltrimethylammonium chloride (APTAC) monomers were synthesized via conventional redox initiated free radical copolymerization using N,N-methylenebis(acrylamide) (MBAA) as a crosslinking agent. The resulting nanogels were characterized by means of FTIR and 1H NMR spectroscopy, dynamic light scattering (DLS) and zeta-potential measurements. Surface morphology was analyzed using scanning electron microscopy. Due to the presence of thermally responsive NIPAM units and varying molar ratios of anionic (AMPS) and cationic (APTAC) units, the resulting nanogels were responsive to multiple stimuli in aqueous media and can be used for controlled delivery of dyes. Thus, the NIPAM90-APTAC7.5-AMPS2.5 nanogel with an excess of the cationic units was chosen for immobilization of the anionic dye, methyl orange (MO), whereas the NIPAM90-APTAC2.5-AMPS7.5 nanogel with an excess of the anionic units was chosen for immobilization of the cationic dye, methylene blue (MB). The release kinetics of the dyes from the nanogel was studied depending on the phase transition temperature and the salt content. Mechanism of the dye release from the nanogel matrix was determined using the Ritger-Peppas equation. Disappearance of the ionic contacts between the charged groups of the nanogels and the ionic dyes was suggested to be the main reason for the diffusion of the dyes through the dialysis membrane into external solution.Peer reviewe

Temperature and Salt Responsivity of Anionic, Cationic and Amphoteric Nanogels Based on N-Isopropylacrylamide, 2-Acrylamido-2-Methyl-1-Propanesulfonic Acid Sodium Salt and (3-Acrylamidopropyl) Trimethylammonium Chloride

Three different nanogels possessing anionic, cationic and amphoteric character were synthesized via conven-tional redox initiated free radical copolymerization of N-isopropylacrylamide (NIPAM), 2-acrylamido-2-methyl-1-propanesulfonic acid sodium salt (AMPS) and (3-acrylamidopropyl) trimethylammonium chloride (APTAC). The negatively charged [NIPAM]:[AMPS] = 90:10 mol.%, positively charged [NIPAM]:[APTAC] = = 90:10 mol.%, and charge-balanced amphoteric nanogels [NIPAM]:[APTAC]:[AMPS] = 90:5:5 mol.% ab-breviated as NIPAM90-AMPS10, NIPAM90-APTAC10, and NIPAM90-APTAC5-AMPS5, respectively, were characterized by FTIR spectroscopy, TGA, UV-Vis spectroscopy and DLS measurements. The temperature and salt responsive properties of nanogels in aqueous and aqueous-salt solutions were studied in the tempera-ture range of 25–60 °C and ionic strength (μ) of 0.001–1.0 M NaCl. Anionic NIPAM90-AMPS10 and cationic NIPAM90-APTAC10 nanogels, exhibit a pronounced polyelectrolyte effect in aqueous-salt solution due to screening of the negative or positive charges by low-molecular-weight salt. Whereas the charge-balanced amphoteric nanogel NIPAM90-APTAC5-AMPS5 exhibits an antipolyelectrolyte effect due to the screening of electrostatic attraction between opposite charges by low-molecular-weight salt. The difference between the temperature-dependent behaviors of anionic, cationic and amphoteric nanogels is explained by shrinking (polyelectrolyte effect) and expanding (antipolyelectrolyte effect) of macromolecular chains in aqueous-salt solutions

Synthesis and characterization of novel thermo- and salt-sensitive amphoteric terpolymers based on acrylamide derivatives

A novel linear amphoteric terpolymers based on neutral monomer - N-isopropylacrylamide (NIPAM), anionic monomer - 2-acrylamido-2-methyl-1-propanesulfonic acid sodium salt (AMPS), and cationic monomer - (3-acrylamidopropyl) trimethylammonium chloride (APTAC) were synthesized by free-radical polymerization in aqueous solution and characterized by methods of H-1 NMR and FTIR spectroscopy, TGA, GPC, Dynamic light scattering (DLS) and zeta-potential. The thermal and salt sensitivity of amphoteric ternary polymers of various compositions, particularly, [NIPAM]:[AMPS]:[APTAC] = 90:2.5:7.5; 90:5:5; 90:7.5:2.5 mol.% were studied in aqueous and aqueous-salt solutions in the temperature range from 25 to 60 degrees C and at the NaCl ionic strength. interval from 10(-3) to 1M. It was found that due to hydrophobic/hydrophilic balance, the temperature dependent conformational and phase change of macromolecular chains becomes sensitive to salt addition and allows the fine-tuning of the phase transition. In aqueous and aqueous-salt solutions, the average hydrodynamic size of amphoteric terpolymers is varied from 8 to 300 nm exhibiting bimodal distribution at room temperature. The number average (M-n) and weight average (M-w) molecular weights, polydispersity index (PDI), and zeta-potentials of amphoteric terpolymers in aqueous solutions were determined.Peer reviewe

Temperature and Salt Responsive Amphoteric Nanogels Based on N-Isopropylacrylamide, 2-Acrylamido-2-methyl-1-propanesulfonic Acid Sodium Salt and (3-Acrylamidopropyl) Trimethylammonium Chloride

Polyampholyte nanogels based on N-isopropylacrylamide (NIPAM), (3-acrylamidopropyl) trimethylammonium chloride (APTAC) and 2-acrylamido-2-methyl-1-propanesulfonic acid sodium salt (AMPS) were synthesized via conventional redox-initiated free radical copolymerization. The resultant nanogels of various compositions, specifically [NIPAM]:[APTAC]:[AMPS] = 90:5:5; 90:7.5:2.5; 90:2.5:7.5 mol.%, herein abbreviated as NIPAM(90)-APTAC(5)-AMPS(5), NIPAM(90)-APTAC(7.5)-AMPS(2.5) and NIPAM(90)-APTAC(2.5)-AMPS(7.5), were characterized by a combination of H-1 NMR and FTIR spectroscopy, TGA, UV-Vis, DLS and zeta potential measurements. The temperature and salt-responsive properties of amphoteric nanogels were studied in aqueous and saline solutions in a temperature range from 25 to 60 degrees C and at ionic strengths (mu) of 10(-3) to 1M NaCl. Volume phase transition temperatures (VPTT) of the charge-balanced nanogel were found to reach a maximum upon the addition of salt, whereas the same parameter for the charge-imbalanced nanogels exhibited a sharp decrease at higher saline concentrations. A wide bimodal distribution of average hydrodynamic sizes of nanogel particles had a tendency to transform to a narrow monomodal peak at elevated temperatures and higher ionic strengths. According to the DLS results, increasing ionic strength results in the clumping of nanogel particles.Peer reviewe

Temperature Dependent Behavior of Oil Dispersion System in Bulk and on the Metal Surface

This article focuses on the temperature dependent behavior of oil dispersion systems containing high amount of paraffins. In particular the properties of oils in bulk and during the contact with metal surface were evaluated by methods of rheoviscometry, thermal analysis, differential scanning calorimetry, gravimetry, polarization microscopy, gas chromatography and chemical analysis.Analysis of rheological parameters of oil, morphology of paraffin crystals, and thermal properties at temperature interval between 0÷90 0С allowed to determine the transition temperature of oil dispersion system from the molecular to free-dispersal and bounded-dispersal states. It was established that the indicated parameters depend on oil composition, molecular-mass distribution of paraffins, curing temperature and cooling rate.Contacting of high paraffinic oils with steel surface leads to formation of asphaltene-resin-paraffin deposition (ARPD). The quantity, structure, composition and adhesiveness of ARPD depends on oil composition and gradient of temperature between heated oil and cooled metal surface. In case of temperature gradient is more than 30 0С the solid and high adhesive depositions are formed. Their structure is enriched by long chain high-melting paraffins. In case of temperature gradient is less than 20 0С, amorphous and easy removable depositions are formed. Their structures are enriched by mechanical admixtures, water, resin, asphaltene and low-melting short chain paraffins.Key words: High-paraffinic oil; Oil dispersion system; Asphaltene-resin-paraffin depositions; Wax appearance temperature; Heat treatmen

Lakhta Center: Automated Structural and Geotechnical Health Monitoring

"Lakhta Center" became a large scale public and office project in Primorskiy district of Saint-Petersburg, Russia. The Complex is comprised of supertall Tower, Multifunctional Building and the Arch with long span structures integrated with stylobate part. A number of innovation technologies and design solutions have been applied during the construction of the project. According to the Building Codes and Regulations, to improve structural safety during the construction and maintenance periods, permanent structural health monitoring (SHM) program has been developed. The main objective of SHM is to minimize structural failure risks due to uncertainties in soil and structural materials behavior. General information about design and organizational arrangements for deploying automated structural and geotechnical health monitoring system of the "Lakhta Tower" is provided in the following paper. SHM architecture and topology, applied instrumentation, measurement methodology, software and monitoring parameters of the structure are described. The article presents the results of the Tower structural behavior monitoring during the construction period. The correlation between the measured and the predicted Tower structure performance was analyzed and found in good agreement. A few anomalies were identified and investigated. The focus is made to the informational value of the monitoring data for the increasing of soil, foundation and structure FE-modelling quality for construction accompaniment purposes

Surface softening in metal-ceramic sliding contacts: An experimental and numerical investigation

This study investigates the tribolayer properties at the interface of ceramic/metal (i.e., WC/W) sliding contacts using various experimental approaches and classical atomistic simulations. Experimentally, nanoindentation and micropillar compression tests, as well as adhesion mapping by means of atomic force microscopy, are used to evaluate the strength of tungsten?carbon tribolayers. To capture the influence of environmental conditions, a detailed chemical and structural analysis is performed on the worn surfaces by means of XPS mapping and depth profiling along with transmission electron microscopy of the debris particles. Experimentally, the results indicate a decrease in hardness and modulus of the worn surface compared to the unworn one. Atomistic simulations of nanoindentation on deformed and undeformed specimens are used to probe the strength of the WC tribolayer and despite the fact that the simulations do not include oxygen, the simulations correlate well with the experiments on deformed and undeformed surfaces, where the difference in behavior is attributed to the bonding and structural differences of amorphous and crystalline W-C. Adhesion mapping indicates a decrease in surface adhesion, which based on chemical analysis is attributed to surface passivation