Synthesis and characterization of acetylated syndiotactic polystyrene

Acetylation of highly stereoregular syndiotactic polystyrene has been accomplished in a heterogeneous process by using carbon disulfide as the dispersing medium, and acetyl chloride and anhydrous aluminium chloride as acetylating agent and catalyst, respectively. The acetylation reaction can be well controlled and carried out to a high degree of acetylation. The resultant polymer was characterized by FTIR and NMR spectroscopy. The incorporation of acetyl groups into syndiotactic polystyrene was found to have an effect on the thermal properties of these new materials. The degree of crystallinity was decreased by the presence of acetyl groups, while the glass transition temperature increased. Copyright © 2004 Society of Chemical Industry     

Design and economic analysis of the technological scheme for 1,3-propanediol production from raw glycerol

A technological scheme for producing 1,3-propanediol from raw glycerol was designed, simulated, and economically assessed. The production process was composed of three main stages, namely: glycerol purification, glycerol fermentation, and 1,3-propanediol recovery and purification. First, a typical stream of raw glycerol was purified up to 98 wt %, and then the fermentation took place in a two continuous stages process by means of a Klebsiella pneumoniae strain. For the fermentation stage, a rigorous analysis was carried out using a kinetic model considering both substrate and products inhibition. Thus, multiplicity of steady states and hysteresis loops were studied for the first fermentation stage. Also, in order to optimize both the outlet concentration of 1,3-propanediol and its productivity, three different objective functions were analyzed. As result, each objective function led to an optimal condition, such as: the highest global yield to 1,3-propanediol (0.599 mol/mol), the highest outlet concentration of 1,3-propanediol (0.512 mol/L), and the highest global productivity (1.157 × 10^?2), respectively. Then, the downstream process for 1,3-propanediol recovery and purification was designed based on a reactive-extraction process and a reactive-distillation process. This downstream process was applied to each scenario analyzed on the fermentation stage. Finally, the three scenarios were economically assessed and the lowest production cost was obtained for the third scenario. Simulation process and fermentation analysis were performed using Aspen Plus and MatLab respectively, while the economic assessment was carried out using the Aspen Icarus Process Evaluator.     

The thermal decomposition of granular and fluid soybean lecithins

The effect of heat on the decomposition of two grades of soybean lecithin has been examined up to 600°C using differential scanning calorimetry and thermogravimetry. Studies were carried out in both air and argon and a kinetic analysis of the isothermal rates of reaction was attempted. Three principal decomposition stages were distinguished in argon and four in air for a water-dispersible lecithin typical of the quality of the material used in many industrial applications. Gas chromatography showed that the principal gases evolved from 50 to 600°C in argon from the water-dispersible lecithin in contact with aluminum surfaces were C₁-C₆ hydrocarbons, carbon dioxide, carbon monoxide, water and traces of hydrogen.     

Emulsifying Properties of Lecithin Containing Different Fatty Acids Obtained by Immobilized Lecitase Ultra-Catalyzed Reaction

Lecitase Ultra and 6 triacylglycerol lipases (lipases PS, M, AH, AY, R, and AK) were immobilized on Amberlite XAD 7HP and used to catalyze the acidolysis reaction between lecithin and capric acid (C10:0) for comparison. The highest molar incorporation value (51.0 mol%) was observed for the immobilized Lecitase Ultra. Further, immobilized Lecitase Ultra was selected for catalyzing acidolysis between lecithin and fatty acids with different chain lengths (C6:0, C8:0, C10:0, C12:0, and C14:0). After reaction, free fatty acids were removed by SPE and the resultant was called modified lecithin fraction 1 (MLF1). The highest molar incorporation value was obtained for C10:0 (51.0 mol%) at 45 °C with a mole ratio of 10/1 (C10:0/lecithin) for 72 h. After removal of lysophosphatidylcholine by solid-phase extraction from MLF1, the resultant modified lecithin fraction 2 (MLF2) was used to prepare an oil-in-water emulsion. All emulsions prepared with MLF2 exhibited significantly higher emulsion stability (ES) values (16.2–17.7) and smaller particle sizes (d ₃₂ 0.40–0.49 μm, d ₄₃ 0.75–1.01 μm) than the emulsion prepared with unmodified lecithin (ES 14.1, d ₃₂ 0.76 μm, d ₄₃, 1.26 μm) (P < 0.05). Furthermore, less clarification and droplet aggregation were observed in emulsions prepared with MLF2 than in lecithin-based emulsions. Overall, the MLF2s showed better emulsifying properties than lecithin.     

Acetylation of Wood with Various Catalysts

Abstract

The purpose of this study was to compare two different acetylation mechanisms using acetic anhydride (AA) or vinyl acetate (VA) modification with using various catalysts. Acetylation of Scots pine wood flour with acetic anhydride could be significantly improved in the presence of potassium acetate, potassium carbonate, and sodium carbonate at 100°C. Sodium carbonate had low effect on VA acetylation, potassium acetate was found to be more effective, and potassium carbonate was better for vinyl acetate modification of wood flour. The two modification methods and the effect of different catalysts on AA or VA modification were characterized by infrared and NMR spectra and analyzed in detail. The acetylation of Scots pine flour with VA and AA showed almost the same WPG values for catalysts when based on long reaction times.     

Regioselective Alcoholysis of Silychristin Acetates Catalyzed by Lipases

A panel of lipases was screened for the selective acetylation and alcoholysis of silychristin and silychristin peracetate, respectively. Acetylation at primary alcoholic group (C-22) of silychristin was accomplished by lipase PS (Pseudomonas cepacia) immobilized on diatomite using vinyl acetate as an acetyl donor, whereas selective deacetylation of 22-O-acetyl silychristin was accomplished by Novozym 435 in methyl tert-butyl ether/n-butanol. Both of these reactions occurred without diastereomeric discrimination of silychristin A and B. Both of these enzymes were found to be capable to regioselective deacetylation of hexaacetyl silychristin to afford penta-, tetra- and tri-acetyl derivatives, which could be obtained as pure synthons for further selective modifications of the parent molecule.     

乙酰基二茂铁的合成

以三氯化铝为催化剂,乙酰氯为酰化剂,在二氯乙烷中对二茂铁酰化得到了产率较高的乙酰基二茂铁。研究了反应温度、加料方式和反应物摩尔比对反应的影响。     

Lipase‐mediated preparation of epoxy lecithin and its evaluation as plasticizer in polyester laminates

A simple chemoenzymatic method was developed for the preparation of epoxy lecithin that contains epoxy oils and phospholipids. The parameters such as lipase concentration, hydrogen peroxide concentration, and time of the reaction were studied. The product was evaluated as a plasticizer in polyester laminates and compared with virgin polyester laminates. The laminates were prepared using various amounts of epoxy lecithin and evaluated for different properties. The epoxy lecithin modified laminates showed good impact strength, tensile, and chemical resistance properties. These laminates were also evaluated for vicat softening point and water absorption. The epoxy lecithin can be used as a plasticizer in polyester laminates. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Spectral, Thermal and Structural Studies of Poly[μ-acetato(4-aminobenzoato)lead(II) monohydrate]: A Polymeric Hydrated Lead(II) Complex with Acetate Bridges

Single crystals of a lead(II) complex of 4-aminobenzoic acid, [Pb(Paba)(CH₃COO)]·H₂O (PabaH = 4-aminobenzoic acid) were successfully grown by gel diffusion technique using sodium metasilicate. The grown crystals were characterized by elemental analysis, fourier transform infrared (FT-IR) and UV–Vis spectroscopic techniques. The crystalline nature of the grown complex was confirmed by the powder X-ray diffraction (XRD) studies. FT-IR spectral studies were carried out to identify the functional groups. Thermal properties of the compound were studied using thermogravimetric analysis. The structure of the complex was elucidated by single crystal XRD studies. The title compound crystallizes in the centrosymmetric monoclinic space group P2₁/c and is having a polymeric structure. The polymeric array is constructed by the oxygen atom of acetate group and nitrogen atom of the aminobenzoate group.     

Synthesis and characterization of siliconized epoxy-1,3-bis(maleimido)benzene intercrosslinked matrix materials

Intercrosslinked network of siliconized epoxy-1,3-bis(maleimido)benzene matrix systems have been developed. The siliconization of epoxy resin was carried out by using various percentages of (5-15%) hydroxyl-terminated polydimethylsiloxane (HTPDMS) with γ-aminopropyltriethoxysilane (γ-APS) as crosslinking agent and dibutyltindilaurate as catalyst. The siliconized epoxy systems were further modified with various percentages of (5-15%) 1,3-bis(maleimido)benzene (BMI) and cured by using diaminodiphenylmethane (DDM). The neat resin castings prepared were characterized for their mechanical properties. Mechanical studies indicate that the introduction of siloxane into epoxy resin improves the toughness of epoxy resin with reduction in the values of stress-strain properties whereas, incorporation of bismaleimide into epoxy resin improves stress-strain properties with lowering of toughness. However, the introduction of both siloxane and bismaleimide into epoxy resin influences the mechanical properties according to their percentage content. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and measurement of heat distortion temperature were also carried out to assess the thermal behavior of the matrix samples. DSC thermogram of the BMI modified epoxy systems show unimodel reaction exotherms. The glass transition temperature (T_g), thermal degradation temperature and heat distortion temperature of the cured BMI modified epoxy and siliconized epoxy systems increase with increasing BMI content and this may be due to the homopolymerization of BMI rather than Michael addition reaction. The morphology of the BMI modified epoxy and siliconized epoxy systems were also studied by scanning electron microscopy.     

Microbial Oxidation of Medium Chain Fatty Alcohol in the Synthesis of Sophorolipids by Candida bombicola and its Physicochemical Characterization

Sophorolipids (SL) are glycolipid biosurfactants abundantly produced from different feedstocks by yeasts and have been widely developed for various applications. The amphipathic structures of sophorolipids imparts to them surfactant type properties. These biosurfactants are readily isolated in high yield and are nontoxic and biodegradable, which make them industrially interesting as surfactants or emulsifiers. Sophorolipid production was carried out using glucose as a hydrophilic source and lauryl alcohol C_12–14, as a hydrophobic source by Candida bombicola (ATCC 22214). Process economics and environmental attractiveness was increased by using a low cost substrate. Optimization studies were carried out where the effect of glucose concentration, pH, temperature and metal ions on sophorolipid production was studied. Optimum production of sophorolipid obtained using lauryl alcohol (SLLA) was achieved after 96 h, the initial pH of the medium was 6.0 with 10 % glucose at 30 °C. Primary characterization of SLLA was done by FTIR. The SLLA showed high physicochemical properties in terms of the surface activities when compared with synthetic surfactants including dodecyl tetraethylene glycol ether and sodium lauryl sulfate. The surface tension of SLLA thus obtained was found to be 24 mN/m with a critical micellar concentration (CMC) value of 0.68 mg/L. Antimicrobial testing showed that SLLA have potent antimicrobial activity against both gram negative bacteria, Escherichia coli (ATCC 8739) and gram positive cocci, Staphylococcus aureuss (ATCC 2079).     

Studies on self cured zinc-containing Pongamia glabra oil based polyesteramide

Efforts have been made for the development of high performance protective coating materials from non drying oil such as Pongamia glabra oil and their commercialization. Zn-containing self cured Pongamia glabra oil based polyesteramide [Zn-APGPEA] resin was synthesized in situ by the reaction of Pongamia glabra fatty amide diol [HEPGA], poly(styrene-co-maleic anhydride) [SMA] and zinc acetate (different ratios) at 100 ± 5 °C in the presence of an acid catalyst. The physico-chemical characterizations of the resin were carried out by standard laboratory methods. The structural elucidation of the prepared resin was carried out by FTIR, ¹H NMR and ¹³C NMR spectral techniques. The thermal behavior was studied by TGA technique. Antibacterial activity was measured by agar diffusion method against Escherichia coli and Staphylococcus aureus. The effect of the loading of zinc on properties of Zn-APGPEA film was also investigated. The properties of Zn-APGPEA compared with reported self cured Pongamia glabra polyesteramide [APGPEA]. Physico-mechanical and chemical/corrosion resistance test of Zn-APGPEA coatings showed that the presence of zinc metal in APGPEA considerably enhances the overall film performance and also improves antibacterial activity. Therefore, Zn-APGPEA can be used as an anti-corrosive and antibacterial coatings material which may substitute polymers obtained from petroleum.     

Formulation Optimization of a Palm-Based Nanoemulsion System Containing Levodopa

Response surface methodology (RSM) was utilized to investigate the influence of the main emulsion composition; mixture of palm and medium-chain triglyceride (MCT) oil (6%–12% w/w), lecithin (1%–3% w/w), and Cremophor EL (0.5%–1.5% w/w) as well as the preparation method; addition rate (2–20 mL/min), on the physicochemical properties of palm-based nanoemulsions. The response variables were the three main emulsion properties; particle size, zeta potential and polydispersity index. Optimization of the four independent variables was carried out to obtain an optimum level palm-based nanoemulsion with desirable characteristics. The response surface analysis showed that the variation in the three responses could be depicted as a quadratic function of the main composition of the emulsion and the preparation method. The experimental data could be fitted sufficiently well into a second-order polynomial model. The optimized formulation was stable for six months at 4 °C.     

Evaluation of antioxidants for cod liver oil by chemiluminescence and the rancimat method

Commercial blends of natural antioxidants,viz., tocopherol concentrates, rosemary extracts, sage extracts, and lecithins, were tested for their ability to stabilize cod liver oil. The antioxidants were tested by using the Rancimat apparatus at 80°C and by a method based on hypochlorite-activated chemiluminescence analysis of samples stored at 35°C for 24 h in light. In addition, a stability study at 5°C in the dark for 8 wk, under conditions realistic for normal consumption of cod liver oil was carried out. A low correlation (r=0.339) was found between Rancimat induction times and chemiluminescence data for the sixteen antioxidant systems tested, probably due to temperature differences, and different ways of detecting oxidation products. Based on Rancimat induction times, δ-tocopherol-rich antioxidants and lecithin had the best stabilizing effect. However, based on the chemiluminescence method, the tocopherols acted as prooxidants, while tocopherols with lecithin increased the stability. Both Racimat and chemiluminescence data showed stabilizing effects with rosemary and sage extracts, but no synergistic effect between the herbal extracts and lecithin or tocopherol was observed. Analyses of oil aged at 5°C for 8 wk showed the highest stability for cod liver oil containing rose-mary extracts. The tocopherol mixtures showed only a minor effect on the stability. Ranking of antioxidants varied considerably depending on the method used, and increasing the temperature seemed to decrease the usefulness of the method. Antioxidant evaluation has to be done by using as many evaluation methods as possible under conditions relevant for normal storage and use.     

Towards superhydrophobic coatings made by non-fluorinated polymers sprayed from a supercritical solution

The objective of this study was to create a superhydrophobic surface using polymers that are non-fluorinated and applying them to a surface via rapid expansion of a supercritical solution (RESS). Solubility studies of poly(ɛ-caprolactone) (PCL) and a statistical copolymer of vinyl acetate and vinyl pivalate (P(VAc-VPi))in supercritical carbon dioxide (scCO₂) were carried out using an extraction procedure. It was found that the most suitable process parameters for spraying these polymers using the RESS technique were 30 MPa, 40 °C and 10% (v/v) acetone as a co-solvent. The surfaces produced were characterized in terms of their morphology and hydrophobic properties by scanning electron microscopy and contact angle measurements, respectively. The most hydrophobic surfaces were obtained by spraying the P(VAc-VPi) copolymers, giving advancing water contact angles in the range of 120–155° due to the hydrophobic character of the polymer and the microstructure formed with the RESS technique. These results show great promise for the creation of superhydrophobic surfaces using non-fluorinated polymers applied to surfaces via RESS technique.     

Radiation-induced Grafting of Acrylic Acid and Vinyl Acetate Monomers onto Heavy-duty Poly(ethylene–vinyl acetate) Films

The preparation of graft films was carried out by direct radiation-induced graft polymerization of acrylic acid and vinyl acetate comonomer onto heavy-duty poly(ethylene–vinyl acetate) films. The effect of various comonomer compositions on the degree of grafting was investigated. The characterization and some selected properties of the graft copolymers prepared were studied. Thermal stability, mechanical and electrical properties of the films showed great promise for some practical applications. © of SCI.     

Polyurethanes based on 2,2‐Dinitropropane‐1,3‐diol and 2,2‐bis(azidomethyl)propane‐1,3‐diol as potential energetic binders

On the base of 2,2‐bis(azidomethyl)propane‐1,3‐diol (BAMP) and 2,2‐dinitropropane‐1,3‐diol (DNPD) four different polyurethanes were synthesized in a polyaddition reaction using hexamethylene diisocyanate (HMDI) and diisocyanato ethane (DIE). The obtained prepolymers were mainly characterized using vibrational spectroscopy (IR) and elemental analysis. For determination of low and high temperature behavior, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used. Investigations concerning friction and impact sensitivities were carried out using a BAM drop hammer and friction tester. The energetic properties of the polymers were determined using bomb calorimetric measurements and calculated with the EXPLO5 V6.02 computer code. The obtained values were compared with the glycidyl azide polymer (GAP). The compounds turned out to be insensitive toward friction (>360 N) and less sensitive toward impact (40 J). The good physical stabilities, along with their sufficient thermal stability (170–210 °C) and moderate energetic properties renders these polymers into potential compounds for applications as binders in energetic formul;ations. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43991.     

Solvent Extraction of Biologically Derived 1,3-Propanediol with Ethyl Acetate and Ethanol Cosolvent

This study examined the use of ethyl acetate and its mixture with ethanol as cosolvent for the extraction of biologically derived 1,3-propanediol (1,3-PDO) from a fermentional process. Experimental results on extraction of the fermentation model mixture revealed that ethyl acetate was a suitable solvent, having the distribution coefficient of 1,3-PDO of 0.22 at 303.15 K. The temperature (303.15 to 323.15 K) was found not to have a significant effect on the distribution coefficient. On the other hand, the addition of glycerol into the feed aqueous stream (at the concentrations of 4, 8, 12 g/L) was found to increase the distribution coefficient of 1,3-PDOs, however, the compound selectivity decreased. When ethanol was used as a cosolvent at the volume ratio of ethyl acetate to ethanol of 90:10, the distribution coefficient increased from 0.22 to 0.31 at 303.15 K. This decreased the number of theoretical stages (NTS) required to achieve 90% recovery of 1,3-PDO from the aqueous phase from 3 to 2 stages at the solvent to feed (S/F) ratio of 9. In addition, the extraction results with actual fermentation broth at 303.15 K indicated that the use of ethanol cosolvent could improve the distribution coefficient of 1,3 PDO from 0.14 to 0.20.     

Soy lecithin-monoester interchange reaction by microbial lipase

Modification of the fatty acid composition of soy lecithin, principally at its 1-position, was investigated by interchange reaction with the methyl ester of individual fatty acids and a lipase as the catalyst. The consequent effect on the surface activity of soy lecithin was also examined. The interchange reaction was carried out by heating a mixture of soy lecithin and methyl ester of a fatty acid at 60°C for 48 h with 10% (by weight of the reactants) Mucor miehei lipase. The lipase was filtered from the reaction mixture, and the product was isolated by combination of acetone extraction, which removed the methyl ester fraction, and by preparative thin-layer chromatography separation. The soy lecithin showed distinct change in its fatty acid composition in the sn-1 position. Capric acid was incorporated by 8.4%, while lauric acid and myristic acid were introduced at 14.1 and 15.7%, respectively. The linolenic acid percentage was increased by about 10 units. The interfacial tension of soy lecithin changed significantly after incorporation of various saturated fatty acids.     

Synthesis and characterization of moisture‐cured polyurethane membranes and their applications in pervaporation separation of ethyl acetate/water azeotrope at 30°C

NCO‐terminated polyurethane membranes were prepared using diisocyanate, diol, and trimethylolpropane (TMP) using an NCO/OH ratio of 1.6 : 1. Prepolymer was chain‐extended using cellulose acetate butyrate (CAB) in the ratios of 2 : 1, 4 : 1, and 3 : 1 of NCO/OH. Polyurethane (PU) membranes were characterized by differential scanning calorimeter (DSC) and thermogravimetry (TGA) to investigate their thermal properties. Equilibrium sorption studies were carried out at 30°C in water and ethyl acetate media as well as in their binary mixtures. The influence of CAB on pervaporation (PV) separation of an ethyl acetate/water (92/8, w/w, i.e., azeotropic composition) mixture was investigated. Membranes in this study showed a selectivity of 42.42 with a flux value of 0.187 kg/m/h for 3 : 1% NCO/OH containing PU membrane. In order to gain a more detailed picture of the molecular transport phenomenon, we performed the sorption gravimetric experiments at 30°, 35°, 40°, and 50°C to compute diffusion, swelling, sorption, and permeability coefficients of PU membranes in the azeotropic mixture of ethyl acetate and water. Activation parameters for diffusion and permeation were computed from the Arrhenius equation to understand the polymer/solvent interactions. Sorption trends and diffusion anomalies were established through an empirical equation after estimating the diffusion parameters. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3405–3414, 2007