Ester Carbon Research Articles

Effect of (meth)acrylates on in situ visible light polymerization of dimethacrylamide

This study reports in situ visible light copolymerization of a synthesized dimethacrylamide with the selected (meth)acrylates. The effects of these selected comonomers with different functional groups on the polymerization rate, degree of conversion, gel time and compressive strength were investigated. The results showed that in situ copolymerization of the dimethacrylamide with the comonomers having an electron-withdrawing and/or acrylate group could significantly increase the polymerization rate, degree of conversion and compressive strength. Contrarily, an electron-donating group on either carbon–carbon double bond or ester linkage could slow down the polymerization. In comparison, its methacrylate counterpart, triethylene glycol dimethacrylate-based system did not show a clear pattern. The formed H-bonds between (meth)acrylamide and organic acid groups may be responsible for higher compressive strengths. Within the limitation of this study, it is concluded that in situ polymerization of dimethacrylamide under visible light can be accelerated by copolymerization with monomers having electron-withdrawing and/or acrylate groups and vice versa.

BIOSYNTHESIS OF BIOSURFACTANT BY PSEUDOMONAS AERUGINOSA USING CASSAVA FLOUR INDUSTRIAL WASTEWATER AS MEDIA

<span>Biosynthesis of biosurfactant by </span><em>Pseudomonas </em><em>aeruginosa</em><span> have been prepared using cassava flour industrial wastewater (</span><em>manipueira</em><span>) as medium. The optimum condition of the biosurfactans biosynthesis was obtained using media containing nutrient broth and manipueira without centrifugation (NBM) with 4 days fermentation. UV-Vis and FT-IR spectra indicated that the biosurfactant was a rhamnolipid containing hydroxyl, ester, carbocylic and aliphatic carbon chain functional groups. Biosurfactant exhibited critical micelle concentration (CMC) value of 576 mg/L and surface tension value of 0.045 N/m. The biosurfactant was able to decrease the interface tension and form emulsion with benzene, toluene, gasoline and palm oil. This biosurfactant showed w/o emulsion system.</span>

Tribological compatibility analysis of conventional lubricant additives with palm trimethylolpropane ester (TMP) and tetrahedral amorphous diamond-like carbon coating (ta-C)

Modern industrial applications involve rigorous operating conditions due to which lubricant either slips out of the contact or its thin layer resides between the interacting surfaces. Deposition of diamond-like carbon coatings and using lubricants capable of physically adsorbing on the interacting surfaces can significantly improve tribological performance. In this study, tribological compatibility of glycerol mono-oleate, molybdenum dithiocarbamate and zinc dialkyldithiophosphate with palm trimethylolpropane ester and tetrahedral amorphous diamond-like carbon coating has been investigated using universal wear testing machine. For comparison, additive-free and formulated versions of polyalphaolefin were used. Moreover, spectroscopic techniques were used to investigate mechanisms responsible for a particular tribological behavior. Among base oils, trimethylolpropane ester proved to be more effective in enhancing friction performance and mitigating wear of contacts when one of the interacting surfaces was ferrous-based. Self-mated tetrahedral amorphous diamond-like carbon coating surfaces resulted in lowest values of friction and wear coefficient of balls.

Structure Revision of Poecillastrin C and the Absolute Configuration of the β-Hydroxyaspartic Acid Residue.

The planar structure of poecillastrin C (1) was revised through selective reduction of the ester carbon. The absolute configuration of the β-hydroxyaspartic acid (OHAsp) residue was determined to be d-threo by Marfey's analysis. The acid hydrolysate of the reduction product of 1 liberated (2R,3R)-2-amino-3,4-dihydroxybutanoic acid, demonstrating that the β-carboxyl group in poecillastrin C was esterified. The structures of poecillastrins B-D and 73-deoxychondropsin A were also revised.

Effects of South African Silica Sand Properties on the Strength Development and Collapsibility of Single Component Sodium Silicate Binders

Abstract This study shows the results of the investigation of the strength performance, and residual strength of a single component inorganic binder system Cast Clean S27®. The study was conducted using three different foundry sand sources in South Africa. Sample A is an alluvial coastal sample, sample B is an alluvial riverbed sample and Sample C is a blasted sample from a consolidated quartzite rock. The binder was also cured using three different curing mechanisms. The aim of the investigation was to determine the variation of strength performance and residual strength between the different South African sand sources based upon the physical and chemical properties of the sand sources. The moulding sand was prepared using three possible curing mechanisms which are carbon dioxide curing, ester curing and heat curing. The strength measurements were determined by bending strength. Sample A and sample C sand had good strength development. Sample B sand had inferior strength development and excellent high temperature residual strength. The study showed that the single component inorganic binders have good strength development and low residual strength. The silica sand properties have major contributing factors on both strength development and residual strength. The degree of influence of silica sand properties on strength performance and residual strength is dependent on the time of curing and method of curing.

Fractionation of sulfur (S) in beech (Fagus sylvatica) forest soils in relation to distance from the stem base as useful tool for modeling S biogeochemistry

The investigation of the fractionation of S compounds in forest soils is a powerful tool for interpreting S dynamics and S biogeochemistry in forest ecosystems. Beech stands on high pH (nutrient-rich) sites on Flysch and on low pH (nutrient-poor) sites on Molasse were selected for testing the influence of stemflow, which represents a high input of water and dissolved elements to the soil, on spatial patterns of sulfur (S) fractions. Soil cores were taken at six distances from a beech stem per site at 55 cm uphill and at 27, 55, 100, 150 and 300 cm downhill from the stem. The cores were divided into the mineral soil horizons 0–3, 3–10, 10–20, 20–30 and 30–50 cm. Soil samples were characterized for pH, Corg, pedogenic Al and Fe oxides and S fractions. Sequential extraction by NH4Cl, NH4H2PO4 and HCl yielded readily available sulfate-S (RAS), adsorbed sulfate-S (AS) and HCl-soluble sulfate-S (HCS). Organic sulfur (OS) was estimated as the difference between total sulfur (ToS) and inorganic sulfur (RAS + AS + HCS). Organic sulfur was further divided into ester sulfate-S (ES, HI-reduction) and carbon bonded sulfur (CS). On Flysch, RAS represented 3–6%, AS 2–12%, HCS 0–8% and OS 81–95% of ToS. On Molasse, RAS amounted 1–6%, AS 1–60%, HCS 0–8% and OS 37–95% of ToS. Spatial S distribution patterns with respect to the distance from the tree stem base could be clearly observed at all investigated sites. The presented data is a contribution to current reports on negative input–output S budgets of forest watersheds, suggesting that mineralization of OS on nutrient rich soils and desorption of historic AS on nutrient-poor soils are the dominant S sources, which have to be considered in future modeling of sulfur.

Synthesis of silicon-containing cycloaliphatic diepoxide from biomass-based α-terpineol and the decrosslinking behavior of cured network

The intractable after-treatment problem of thermosetting epoxy resins due to the insolubility and infusibility brings about an ever-increasing pressure on environment. In this work, new degradable silicon-containing cycloaliphatic diepoxide (Epo-Si) was designed and synthesized using biomass-based 2-(4-methylcyclohex-3-enyl)propan-2-ol (α-terpineol) as a major material. After curing with anhydride, large amounts of heat-labile tertiary carbon ester and tertiary C-O ether linkages in the network made the crosslinked Epo-Si degrade at a lower temperature of 269 °C. Moreover, its degradation temperatures could be readily tuned through co-curing with the commercial diepoxide ERL-4221. At room temperature, the shearing strength of the cured Epo-Si is 6.74 MPa, superior to that of ERL-4221 (5.24 MPa), exhibiting excellent adhesion property. More importantly, the cured Epo-Si maintains the high shearing strength up to 240 °C, but when further increasing temperature, the strength rapidly dropped and almost completely lost at around 285 °C. Therefore, if integrated circuits have been encapsulated with Epo-Si, their dismantlement or repair at a suitably lower temperature could be realized without damaging the PCB board. The thermal decrosslinking mechanism of the cured products were investigated by means of isothermal and temperature-programmed thermogravimetric and FTIR spectra in detail.

Preparation and characterization of activated carbons from tobacco stem by chemical activation

ABSTRACTActivated carbons were prepared from tobacco stem by chemical activation using potassium hydroxide (KOH), potassium carbonate (K2CO3), and zinc chloride (ZnCl2). The effects of the impregnation ratio (activating agent/precursor) and activating agents on the physical and chemical properties of activated carbons were investigated. The textual structure and surface properties of activated carbons were characterized by nitrogen (N2) adsorption isotherm, scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR), x-ray photoelectron spectroscopy (XPS), and thermogravimetry (TG). ZnCl2, acting as a superior activating agent compared to the others, produced much more porosity. The maximum specific surface area reached 1347 m2/g, obtained by ZnCl2 activation with an impregnation ratio of 4.0. Moreover, ZnCl2 activation yielded products with an excellent thermostability, attributed to different activation mechanisms. Various oxygen functions were detected on the activated carbon surface, and hydroxyl and ester groups were found to be in the majority.Implications: Tobacco stem, the residue from cigarette manufacturing, is usually discarded as waste, leading to serious resource waste and environmental problems. This study provides an effective utilization available for this solid residue by using it as the starting material in the preparation of activated carbon with chemical activation. Activated carbons with high specific area and various surface functions have been prepared, and the effects of the amount and type of activating agents on the physical and chemical properties of activated carbon were investigated as well.

Esterification of industrial lignin and its effect on the resulting poly(3-hydroxybutyrate-co-3-hydroxyvalerate) or polypropylene blends

Utilisation of lignin in plastic based blends offers a sustainable alternative to non-renewable materials as well as value-added use of technical lignin obtained from pulping operations. To overcome poor compatibility between lignin and plastic, in this study, two industrial lignins (softwood Kraft and agricultural fiber soda) were esterified (with acetic, propionic, butyric, and hexanoic anhydrides) and subsequently blended with poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) or polypropylene (PP) at a weight ratio of 3:7. This paper systematically characterized C2–C6 anhydrides esterified lignins (molar mass, glass transition temperature (Tg), hydrophobicity, and polarity), and provides a comprehensive evaluation of the effect of different lignin esters in the blends on tensile properties, water absorption, thermal transitions, for the first time, spherulite morphology, and dynamic rheological behaviour. Generally, compared to blends with unmodified lignin, a progressive increase of tensile strength (25%) and elongation at break (26%) could be observed with increasing ester carbon chain length in PHBV based systems, while no improvement was seen in PP based systems. Water absorption of PHBV and PP blends decreased by about 50% after lignin esterification. The effect of lignin esterification on the crystallization process was matrix dependent: depression of melting crystallization and occurrence of cold crystallization was observed in PHBV based blends, while the melting crystallization shifted to higher temperature in PP based blends. The lignin acetate and propionate blends were partially miscible showing two-stage glass transitions by thermal mechanical analysis. Esterification led to more uniform dispersion of lignin in the plastic matrix. The frequency of PHBV spherulites increased and their size decreased from 700μm to less than 100μm with addition of lignin acetate and propionate. Lignin hexanoate blends showed a Tg depression and smaller dynamic elastic and viscous moduli than the other lignin esters, suggesting that it acted as a plasticizer.

Esterification of Kraft lignin as a method to improve structural and mechanical properties of lignin‐polyethylene blends

ABSTRACTLignin is a promising candidate for blends with thermoplastic polymers. Still, this endeavour is a challenge due to poor compatibility between both components. In this article, the effect of lignin esterification on the improvement of the compatibility between hardwood Kraft lignin and high‐density polyethylene (PE‐HD) is investigated. For this purpose, lignin was esterified with acetic, propionic, and butyric anhydride; its amount in the blends varied from 10 to 40%. Light microscopic images of blends show a reduction in particle size and a more homogeneous distribution with increasing length of the ester carbon chains (C2 to C4). Modification of lignin enhances the moduli and strength characteristics of the blends. Butyrated lignin performs best, as tensile strength of blends can be retained near that of pure PE‐HD with up to 40% lignin content. An additional investigation of unmodified lignin with reduced particle size confirms that modification is the decisive factor to enhance blend properties; a sole reduction of particle size is insufficient. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44582.

BIOSYNTHESIS OF BIOSURFACTANT BY PSEUDOMONAS AERUGINOSA USING CASSAVA FLOUR INDUSTRIAL WASTEWATER AS MEDIA

<span>Biosynthesis of biosurfactant by </span><em>Pseudomonas </em><em>aeruginosa</em><span> have been prepared using cassava flour industrial wastewater (</span><em>manipueira</em><span>) as medium. The optimum condition of the biosurfactans biosynthesis was obtained using media containing nutrient broth and manipueira without centrifugation (NBM) with 4 days fermentation. UV-Vis and FT-IR spectra indicated that the biosurfactant was a rhamnolipid containing hydroxyl, ester, carbocylic and aliphatic carbon chain functional groups. Biosurfactant exhibited critical micelle concentration (CMC) value of 576 mg/L and surface tension value of 0.045 N/m. The biosurfactant was able to decrease the interface tension and form emulsion with benzene, toluene, gasoline and palm oil. This biosurfactant showed w/o emulsion system.</span>

Influence of lignin source and esterification on properties of lignin-polyethylene blends

Lignins from pulp mills and biorefineries will gain increasing commercial importance in the next years. Their utilisation in polyolefin blends is of growing research interest as it offers a value-added usage of lignin as well as substitution of non-renewable resources. However, the low compatibility of lignin and polyolefins restrains a satisfying blend production and leads to poor mechanical properties. This can be overcome by modifying lignin prior to its incorporation into polymers in order to reduce its polarity. In this study, five lignins from different raw material sources and production processes were esterified with acetic, propionic and butyric anhydride and subsequently mixed with polyethylene with a weight ratio of 1:1. The paper provides a comprehensive and systematic evaluation of the influence of esterification as well as chemical composition of lignins on mechanical properties and, for the first time, water absorption of lignin-polyethylene blends. Properties of blends were found to improve upon lignin esterification. Compared to blends with unmodified lignin, a progressive increase of tensile (+45%) and flexural (+30%) strength could be observed with increasing length of the ester carbon chain. Lignin source and chemical composition affect water absorption of blends, but show no significant effect on mechanical properties as similar values were observed for blends produced with the respective lignin esters.

Crystal structure of N-(3-oxo-butano-yl)-l-homoserine lactone.

The structure and absolute configuration of the title compound, C8H11NO4, which is a known quorum-sensing modulator, have been determined. The mol-ecule exhibits signs of an intra-molecular attractive carbon-yl-carbonyl n→π* inter-action between the amide and lactone ester groups, specifically - a short contact of 2.709 (2) Å between the amide oxygen atom and ester carbon atom, approach of the amide oxygen atom to the ester carbonyl group along the Bürgi-Dunitz trajectory, at 99.1 (1)°, and pyramidalization of the ester carbonyl group by 1.1 (1)°. Moreover, a similar n→π* inter-action is observed for the amide carbonyl group approached by the ketone oxygen donor. These inter-actions apparently affect the conformation of the uncomplexed mol-ecule, which adopts a different shape when bound to protein receptors. In the crystal, the mol-ecules form translational chains along the a axis via N-H⋯O hydrogen bonds.

Exploring the peri-, chemo-, and regio-selectivity of addition of manganese metal oxides MnO3L (L = Cl−, O−, OCH3, CH3) to substituted ketenes: A computational study

Ketenes are interesting reactive intermediates that find a wide range of synthetic applications. Density functional theory calculations at the MO6/LACVP∗ and B3LYP/LACVP∗ levels of theory have been employed to explore the peri-, chemo-, and regio-selectivity of the addition of manganese oxo complexes MnO3L (L=Cl, O−, OCH3, CH3) to substituted ketenes OCC(CH3)(X) [X=H, CH3, Cl, CN, Ph] with the aim of elucidating the effects of substituents on the mechanism of the reactions. The results show that the concerted [3+2] addition of the CC bond of the ketene across the metal complex is the most preferred pathway in all the reactions studied (with respect to changing ligand L on the metal complex or substituent X on the ketene) except in the reaction of MnO4− (i.e. for L=O−) with dimethyl ketene, which follows only a stepwise addition pathway. [2+2] addition is found to be possible only in the reaction of MnO3–OCH3 with dimethyl ketene where the activation barrier for [2+2]CO addition is 23.79kcal/mol, which is far greater than the barrier for the [3+2] addition. The reactions of dimethyl ketene with MnO4− will most likely lead to the formation of an ester precursor and the reaction of MnO3Cl with the substituted ketenes would lead to the formation of an ester precursor, chlorohydrin precursor, acetaldehyde and carbon monoxide (for X=H, Cl). Generally, reactions involving an increase in oxidation state of metal have higher activation barriers. For both [3+2] and [2+2] addition, low activation barriers are obtained when the substituent on the ketene is electron-donating while high activation barriers are obtained when the substituent is electron-withdrawing. The reactions of ketenes with MnO3L complexes have lower activation barriers for the preferred [3+2] and [2+2] addition pathways as well as fewer side reactions than those of the ReO3L complexes reported in the literature, a trend which was seen in our earlier work with reactions of group VII metals with olefins, implying that manganese oxo complexes efficiently and selectively catalyze specific reactions in oxidation of ketenes and olefins than do Re oxo complexes and therefore Mn oxo complexes may be better catalysts for specific oxidation reactions of ketenes and olefins than Re complexes are.

Low pressure vapor–liquid equilibria modeling of biodiesel related systems with the Cubic–Plus–Association (CPA) equation of state

Fatty acid esters have a wide range of applications in various chemical industries, such as pharmaceutical, cosmetic, food and, most recently, in the biodiesel production. Being able to predict the phase equilibria at reduced pressures of systems composed either only of fatty acid esters as well as also of their mixtures with alcohols, is of major relevance for the design, optimization and operation of industrial facilities producing these compounds, or their use as fuels.In the present work, the Cubic–Plus–Association Equation of State (CPA EoS) was applied to predict the isobaric vapor–liquid equilibria of six binary systems composed of ethyl/methyl fatty acid esters from laurate to linoleate in the pressure range 0.5–13.3kPa, and the isothermal phase equilibria of the binary systems tetradecane+ethyl caproate/ethyl myristate at temperatures from 373.15 to 453.15K.The predictive ability of the CPA EoS was further evaluated in the description of multicomponent biodiesel systems with associating compounds. Using binary interaction parameters computed from fatty acid ester carbon number correlations previously established the equation was able to provide excellent predictions for the low pressure vapor–liquid equilibria of the systems soybean methylic biodiesel+methanol, soybean ethylic biodiesel+ethanol, Jatropha curcas methylic biodiesel+methanol, Jatropha curcas ethylic biodiesel+ethanol, in the pressure range 6.7–66.7kPa.

11th Euro Fed Lipid Congress, New Strategies for a High Quality Future (27–30 October 2013, Antalya, Turkey)

11th Euro Fed Lipid Congress, New Strategies for a High Quality Future (27–30 October 2013, Antalya, Turkey)

Relaxation dynamics and cold crystallization of poly(pentamethylene terephthalate) as revealed by dielectric spectroscopy

The relaxation dynamics of poly(pentamethylene terephthalate) has been investigated by means of dielectric spectroscopy. The sub-glass dynamics is characterized by the existence of a bimodal β process whose faster and slower components have been assigned to the relaxation of the bond between the ester oxygen and the aliphatic carbon and to the link between the aromatic ring carbon and the ester carbon, respectively. By comparison with other closely related aromatic polyesters it is shown that the faster component strongly depends on the amount of methylene groups while the slower one is not considerably affected by the nature of the glycol subunit. The changes in the α process associated to the segmental relaxation during cold crystallization reveal the formation of a rigid amorphous phase fraction. Combination of dielectric experiments with X-ray scattering ones suggests that during cold crystallization PPT crystal lamellae tend to fill the space homogeneously.

PRODUCTION AND CHARACTERIZATION OF BIOSURFACTANT BY Pseudomonas fluorescens USING CASSAVA FLOUR WASTEWATER AS MEDIA

Biosurfactant with efficient emulsification properties could be produced by Pseudomonas flourescens using cassava flour wastewater (manipueira) as media. The ability of P. flourescens to produce biosurfactant could suggest potential use in industrial and environmental applications. Media containing a mixture of natural manipueira and nutrient broth with 48 h fermentation was the optimum condition for the biosurfactant production. Based on UVVis and FT-IR spectra, the biosurfactant was indicated as rhamnolipids containing hydroxyl, ester, carboxylic and aliphatic carbon chain functional groups. Biosurfactant exhibited critical micelle concentration (CMC) value of 715 mg/L and reduced the surface tension of the water from 80 mN/m to 59 mN/m. The biosurfactant was able to decrease the interfacial tension about 51-70% when benzyl chloride, palm oil and kerosene were used as waterimmiscible compounds. The biosurfactant was able to form stable emulsion until 30 days when paraffin, soybean oil, lubricant oil and kerosene were used as water-immiscible compounds.

PRODUCTION AND CHARACTERIZATION OF BIOSURFACTANT BY <i>Pseudomonas fluorescens</i> USING CASSAVA FLOUR WASTEWATER AS MEDIA

Biosurfactant with efficient emulsification properties could be produced by Pseudomonas flourescens using cassava flour wastewater (manipueira) as media. The ability of P. flourescens to produce biosurfactant could suggest potential use in industrial and environmental applications. Media containing a mixture of natural manipueira and nutrient broth with 48 h fermentation was the optimum condition for the biosurfactant production. Based on UV-Vis and FT-IR spectra, the biosurfactant was indicated as rhamnolipids containing hydroxyl, ester, carboxylic and aliphatic carbon chain functional groups. Biosurfactant exhibited critical micelle concentration (CMC) value of 715 mg/L and reduced the surface tension of the water from 80 mN/m to 59 mN/m. The biosurfactant was able to decrease the interfacial tension about 51-70% when benzyl chloride, palm oil and kerosene were used as water-immiscible compounds. The biosurfactant was able to form stable emulsion until 30 days when paraffin, soybean oil, lubricant oil and kerosene were used as water-immiscible compounds.

Comparative Study of the Autoignition of Methyl Decenoates, Unsaturated Biodiesel Fuel Surrogates

The autoignition of methyl 9-decenoate and a mixture of methyl 5-decenoate and methyl 6-decenoate [methyl 5(6)-decenoate], biodiesel fuel surrogate compounds structurally representative of unsaturated compounds found in fatty acid methyl ester (FAME) fuels, has been studied using the shock tube technique. Measurements of ignition delay times were made in reflected shock-heated gases at pressures around 20 atm for fuel/air mixtures at equivalence ratios of 0.5, 1.0, and 1.5 and at a wide range of temperatures from 700 to 1300 K, spanning a range of temperatures relevant to autoignition in compression ignition engines. A comparison of ignition delay times for the methyl decenoates and methyl decanoate illustrates the influence of the presence and location of a double bond within the methyl ester carbon chain on low- and high-temperature reactivities. At high temperatures (>900 K), the three surrogate components have indistinguishable ignition delay. While in the negative temperature coefficient (NTC) and lo...