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Emulsifier
Selected AbstractsAllergic contact dermatitis from sodium stearoyl lactylate, an emulsifier commonly used in food productsCONTACT DERMATITIS, Issue 2 2005Charlotte D. Jensen No abstract is available for this article. [source] Mesotherapy and Phosphatidylcholine Injections: Historical Clarification and ReviewDERMATOLOGIC SURGERY, Issue 4 2006ADAM M. ROTUNDA MD BACKGROUND Mesotherapy was originally conceived in Europe as a method of utilizing cutaneous injections containing a mixture of compounds for the treatment of local medical and cosmetic conditions. Although mesotherapy was traditionally employed for pain relief, its cosmetic applications, particularly fat and cellulite removal, have recently received attention in the United States. Another treatment for localized fat reduction, which was popularized in Brazil and uses injections of phosphatidylcholine, has been erroneously considered synonymous with mesotherapy. Despite their attraction as purported "fat-dissolving" injections, the safety and efficacy of these novel cosmetic treatments remain ambiguous to most patients and physicians. OBJECTIVE To distinguish mesotherapy from phosphatidylcholine injections by reviewing their history and the relevant experimental or clinical findings. METHODS A comprehensive search of Medline indexed literature and conference proceedings. RESULTS All the published studies evaluating the clinical efficacy of traditional mesotherapy currently originate from Europe. These reports focus primarily on musculoskeletal pain and vascular disease, rather than cosmetic applications. Although experimental data suggest that a number of traditional mesotherapy ingredients may theoretically reduce fat, these effects have not been supported in peer-reviewed studies. An increasing number of reports demonstrate that subcutaneous injections of a formula containing phosphatidylcholine combined with its emulsifier, deoxycholate, are effective in removing small collections of adipose tissue. Cell lysis, resulting from the detergent action of deoxycholate, may account for this clinical effect. CONCLUSIONS Mesotherapy is distinct from a method of treating adipose tissue with subcutaneous injections of deoxycholate alone or in combination with phosphatidylcholine. Additional clinical and experimental studies are necessary to more definitively establish the safety and efficacy of these treatments. [source] Development of emulsion from rhizobial fermented starch industry wastewater for application as Medicago sativa seed coatENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 3 2010Rojan Pappy John Abstract Starch industry wastewater was efficiently employed for the production of Sinorhizobium meliloti and the concentrated culture was used for the development of a biofertilizer formulation. Tween-80 (0.02,g/L) acted as the best emulsifier for a Sinorhizobium,canola oil emulsion. The stability of the emulsion and survival of the organism was enhanced by supplementation of xanthan gum at pH 8. The refrigerated condition was most favorable for stability and survival of the microorganism. The survival of microorganism at 4±1°C was 2.78×1010 and 2.01×1010,CFU (colony forming unit)/mL on storage for 1 and 2 months, respectively. The values were higher than the prescribed cell count (×103,CFU/mL) for field application. At 40°C, the survival of bacteria reduced from 3×1010,CFU/mL to 8.1×109 and 8.8×106,CFU/mL in 1 and 2 months, respectively. Emulsion-coated seed was incubated at different temperatures and a cell count of 105,CFU/seed was observed after 2 months of storage at 4°C, which was equal to the highest level of the described requirement (103,105,CFU/seed). Emulsion supplemented with xanthan gum improved the shelf-life under optimized conditions (Sinorhizobium concentrate,,,canola oil (1:1) emulsion with 0.02,g/L Tween-80; storage at pH 8 and temperature 4±1°C) and this emulsion with the required cell count and prolonged viability was used for the pre-inoculation of seed or for in situ soil application. [source] Horizontal transfer of an exopolymer complex from one bacterial species to anotherENVIRONMENTAL MICROBIOLOGY, Issue 4 2000D. Osterreicher-Ravid Alasan, the exocellular polymeric emulsifier produced by Acinetobacter radioresistens KA53 was shown to bind to the surface of Sphingomonas paucimobilis EPA505 and Acinetobacter calcoaceticus RAG-1. The presence of alasan on the surface of S. paucimobilis EPA505 and A. calcoaceticus RAG-1 caused a decrease in their cell-surface hydrophobicities. Binding was proportional to the concentration of recipient cells and input alasan. At the highest concentration of A. calcoaceticus RAG-1 (4 × 109 ml,1) and alasan (20 µg ml,1) tested, 75% of the alasan was cell bound. Alasan binding was measured by the loss of emulsifying activity and alasan protein and polysaccharide from the aqueous phase after incubation of alasan with the recipient cells. In addition, alasan was visualized on the surface of the recipient cells by staining with anti-alasan antibodies and rhodamine-labelled secondary antibodies. Moreover, when the alasan-producing A. radioresistens KA53 was grown together with A. calcoaceticus RAG-1, alasan was released from the producing strain and became bound to the recipient RAG-1 cells, as demonstrated by fluorescence microscopy. This horizontal transfer of exopolymers from one bacterial species to another has significant implications in natural microbial communities, coaggregation and biofilms. [source] The characterization of the semi-solid W/O/W emulsions with low concentrations of the primary polymeric emulsifierINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 2 2005D. Vasiljevic Synopsis Semi-solid multiple W/O/W emulsions with low concentrations (0.8, 1.6 and 2.4% w/w) of lipophilic polymeric primary emulsifier PEG-30-dipolyhydroxystearate (PDHS) have been formulated. Both emulsions, primary and multiple, were prepared with high content of inner phase (,1 = ,2 = 0.8). All the formulations differ only in the lipophilic emulsifier concentration. Evaluating several parameters such as macroscopic and microscopic aspect, droplet size, accelerated stability under centrifugation and flow and oscillatory rheological behaviour, assessed the multiple systems. It is possible to formulate the semi-solid W/O/W multiple emulsions with low concentrations of PDHS as the primary emulsifier. It appeared that the highest long-term stable multiple emulsion with the lowest droplet size, the highest apparent viscosity and highest elastic characteristic, was the sample with the highest concentration (2.4% w/w) of the primary emulsifier. Résumé Les émulsions H/L/H semi-solides ont été formulées avec les concentrations basses (0.8, 1.6 et 2.4% m/m) de l'émulsifiant lipophile polymèrique PEG-30-dipolyhydroxystearate. Les émulsions simples et multiples ont été préparées avec la teneur élevée en phase intérieure (,1 = ,2 = 0.8). La teneur en émulsifiant lipophile était la seule différence entre ces formulations. L'aspect macroscopique et microscopique, la taille de globules, la stabilité physique déterminée par le test de centrifugation ainsi que le comportement rhéologique (rhéologie d'écoulement et oscillatoire) ont permis l'évaluation des émulsions multiples. Il est possible de formuler les émulsions H/L/H semi-solides multiples avec les concentrations basses de PEG-30-dipolyhydroxystearate comme émulsifiant primaire. Il a été découvert que l'émulsion H/L/H multiple avec le plus grand pourcentage (2.4% m/m) de l'émulsifiant primaire a le diamètre de globule le plus petit, la plus grande viscosité apparente et le plus grand module élastique ainsi que la plus longue stabilité. [source] Effect of oil content and processing conditions on the thermal behaviour and physicochemical stability of oil-in-water emulsionsINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 1 2009Megan Tippetts Summary The destabilisation mechanism of oil-in-water (o/w) emulsions was studied as a function of oil content (20% and 40% o/w), homogenisation conditions and crystallisation temperatures (10, 5, 0, ,5 and ,10 °C). A mixture of anhydrous milk fat and soya bean oil was used as the lipid phase and whey protein isolate (2 wt%) as emulsifier. Crystallisation and melting behaviours were analysed using differential scanning calorimetry. Physicochemical stability was measured with a vertical scan macroscopic analyser. Emulsions with 20% oil were found to be less stable than those with 40% oil. For 20% o/w emulsions, the crystallisation was delayed and inhibited in emulsions with smaller droplets and promoted in emulsions with larger droplets when compared with 40% o/w emulsions. Depending on the droplet sizes in the emulsion, the formation of lipid crystals (in combination with the emulsifier) either stabilises (small droplets) or destabilises (big droplets) the emulsion. [source] Stability and optimum polymerized condition of polysiloxane,polyacrylate core/shell polymerADVANCES IN POLYMER TECHNOLOGY, Issue 3 2010Chengyue Ge Abstract The stable emulsion of core/shell latex with little coagulum (no more than 0.5% in quality relative to total monomers) has been prepared at low temperature with potassium-persulfate (KPS), sodium formaldehyde sulfoxylate (SFS), and 2,2,-azobis(2-(2-imidazolin-2-yl)propane)dihydrochloride (VA-044) as composite initiators by staged emulsion polymerization. Reactive surfactants were used to significantly improve the stability of emulsion. More interestingly, reverse core/shell structure was investigated when the organic silicon was added in the late period of polymerization. The effects of the emulsifier, initiators, dosage of organic silicon, and monomer's content on conversion and graft efficiency were studied in detail. Moreover, the stability of emulsion was investigated by the values of zeta potential (,) and coagulum. More importantly, the thermal performance and stability of PSI/PA composite latex was studied by the glass transition temperature (Tg). The results showed that there are appropriate values for all factors to obtain high conversion, graft efficiency, and excellent stability: The dosage of surfactant was about 0.44 g, the dosage of VA-044 was about 1000 mg kg,1, the dosage of organic silicon was about 15%, and the monomer's content was about 30%. In addition, the introduction of organic silicon improved the Tg. © 2010 Wiley Periodicals, Inc. Adv Polym Techn 29:161,172, 2010; View this article online at wileyonlinelibrary. DOI 10.1002/adv.20182 [source] Studies on bioemulsifier production by Acinetobacter strains isolated from healthy human skinJOURNAL OF APPLIED MICROBIOLOGY, Issue 2 2001J.R. Patil Aims: In recent years, interest has been growing in the search for novel bioemulsifiers. Many bacterial genera including Acinetobacter have been reported to produce bioemulsifiers. The present study aims to screen Acinetobacter isolates from healthy human skin for bioemulsifier production. Methods and Results: Acinetobacter junii SC14 produced maximum bioemulsifier in the presence of almond oil during stationary growth phase at 37°C and pH 7·2. Partially purified, nondialysable bioemulsifier from SC14 was a proteoglycan. The protein and polysaccharide fractions resulted in 95·2% reconstitution of the emulsification activity. The role of esterase in the release of cell-bound emulsifier and the contribution of capsular polysaccharide to the emulsification activity were observed. Conclusion:Acinetobacter strains from human skin exhibited better emulsification activity than that by burn wound or soil isolates, owing to the inherent differences in chemical microenvironment of their habitats. Significance and Impact of the Study: Investigation of skin commensals, especially acinetobacters, would lead to the discovery of novel bioemulsifiers with interesting properties. Attempts of screening and strain improvement directed towards skin commensals will open up new avenues for strains producing bioemulsifier on a commercial scale. [source] Using anionic polymerizable surfactants in ultrasonically irradiated emulsion polymerization to prepare polymer nanoparticlesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2008Yuhui He Abstract An ionic polymerizable surfactant, sodium sulfopropyl-laurylmaleate (M12), was synthesized and used as an emulsifier, an initiator, and a comonomer in ultrasonically irradiated emulsion polymerization. FTIR spectra and gravimetric method results indicated that copolymers P(Styrene-M12) and P(Butylacrlate-M12) were prepared successfully by ultrasonically irradiated emulsion polymerization and the composition of M12 elevated with the increasing concentration of M12 added. TEM photographs of P(St-M12) showed that the nanoparticles with small diameters (20,45 nm) were prepared. With the increase of M12 concentration, the particle size became smaller and the size distribution became wider. The P(BA-M12) particles size was also small (<100 nm) but the size distribution was wide due to the high reactivity of BA. Because surfmer M12 was chemically bonded with the latex particles, the stability of the copolymer latex prepared by ultrasonically irradiated emulsion polymerization was much better than that of the homopolymer latex (PSt or PBA) prepared by the same way. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Synthesis and comparative physicochemical investigation of partly aromatic cardo copolyestersJOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2007N. B. Joshi Abstract Copolyesters were synthesized through the condensation of 0.0025 mol of 1,1,-bis(3-methyl-4-hydroxyphenyl)cyclohexane, 0.0025 mol of ethylene glycol/propylene glycol/1,4-butanediol/1,6-hexane diol, and 0.005 mol of terephthaloyl chloride with water/chloroform (4:1 v/v) as an interphase, 0.0125 mol of sodium hydroxide as an acid acceptor, and 50 mg of cetyl trimethyl ammonium bromide as an emulsifier. The reaction time and temperature were 2 h and 0°C, respectively. The yields of the copolyesters were 81,96%. The structures of the copolyesters were supported by Fourier transform infrared and 1H-NMR spectral data and were characterized with the solution viscosity and density by a floatation method (1.1011,1.2697 g/cm3). Both the intrinsic viscosity and density of the copolyesters decreased with the nature and alkyl chain length of the diol. The copolyesters possessed fairly good hydrolytic stability against water and 10% solutions of acids, alkalis, and salts at room temperature. The copolyesters possessed moderate-to-good tensile strength (11,37.5 MPa), good-to-excellent electric strength (19,45.6 kV/mm), excellent volume resistivity (3.8 × 1015 to 2.56 × 1017 , cm), and high glass-transition temperatures (148,195°C) and were thermally stable up to about 408,427°C in a nitrogen atmosphere; they followed single-step degradation kinetics involving 38,58% weight losses and 34,59% residues. The copolyesters followed 2.6,2.9-order degradation kinetics. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [source] Miniemulsion polymerization of a fluorinated acrylate copolymer: Kinetic studies and nanolatex morphology characterizationJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2007Qinghua Zhang Abstract A stable fluoroacrylate copolymer emulsion was successfully prepared by miniemulsion polymerization with fluoroacrylate, lauryl methylacrylate, and methyl methacrylate as monomers. Extremely hydrophobic fluoroacrylate, instead of conventional cosurfactants, was used as a reactive cosurfactant to stabilize the miniemulsions. The results indicated that fluoroacrylate retarded Ostwald ripening and allowed the production of stable miniemulsions. The chemical compositions of the copolymer were studied with Fourier transform infrared and 1H-NMR. The average composition of the copolymers prepared with miniemulsions was in good agreement with the feed ratio according to 1H-NMR from the integration ratios corresponding to typical protons of the individual monomers. The particle size distribution and morphology of the latex particles were determined with laser particle analysis and transmission electron microscopy. The particle size of the latex underwent no change in the process of miniemulsion polymerization, but the particle size distributions were broader than those of conventional emulsion polymerization. The effects of various reaction parameters, including the temperature and concentrations of the emulsifier and initiator, on the miniemulsion polymerization were also investigated, and the polymerization rate and conversion increased with increasing concentrations of nonylphenol polyethoxylate (with an average of 40 ethylene oxide units per molecule), cetyltrimethylammonium, and 2,2,-azobisisobutyronitrile. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 641,647, 2007 [source] Lactobionic acid in a natural alkylpolyglucoside-based vehicle: assessing safety and efficacy aspects in comparison to glycolic acidJOURNAL OF COSMETIC DERMATOLOGY, Issue 1 2010Marija Tasic-Kostov BSc Summary Background/aims, Lactobionic acid (LA) is a newer cosmeceutical active belonging to the class of alpha-hydroxyacids (AHAs), showing advantages over them. The aim of part I of this study was to compare efficacy and irritation potential of LA vs. glycolic acid (GA) from two types of vehicles , gel and emulsion. In part II, effects of LA-containing emulsions based on a new, natural emulsifier of alkylpolyglucoside (APG) type were evaluated. Methods, Skin bioengineering was used on 77 healthy volunteers to assess: color as erythema and melanin (MI) index, transepidermal water loss, electrical capacitance and pH of the skin. In part I of the study, the parameters were measured after occlusion and periodically during 2 weeks of test samples application; in part II parameters were measured periodically during 4 weeks. Results/conclusion, LA-containing samples has produced better skin performance when compared with corresponding GA-containing ones, particularly the lack of both skin irritation and skin barrier impairment. When used in vehicles based on a new APG-emulsifier, LA and GA have shown better efficacy, emphasizing the importance of vehicle on the effects of topical actives. LA (6%) in the emulsion based on APGs could be proposed as an alternative to low-molecular AHAs in cosmeceuticals. [source] EFFECT OF EMULSIFIERS AND FUNGAL , -AMYLASE ON RHEOLOGICAL CHARACTERISTICS OF WHEAT DOUGH AND QUALITY OF FLAT BREADJOURNAL OF FOOD PROCESS ENGINEERING, Issue 2 2009ARASH KOOCHEKI ABSTRACT Teftoon, a flat bread made of whole wheat flour, is prepared by hand sheeting of dough, followed by baking. Different emulsifiers, like lecithin, E471 (distilled monoglyceride) and E472 (diacetylated tartaric acid esters of mono- and digelycerid of fatty acids), were added to the flour at various levels ranging between 0.25 and 1.0% w/w, and it was observed that they improved the dough characteristics. Improvement in bread quality parameters, such as force to tear and sensory acceptability, were monitored. Fungal, -amylase was also incorporated into the flour at 5,20 g/100 kg flour basis alone and in combination with the emulsifier. The force required to tear the fresh bread was decreased with emulsifier and enzyme addition; however, E472 addition at 0.75% w/w of whole wheat flour gave the softest bread. The tear force of stored bread significantly increased with storage; however, bread containing E472 showed a less increase in tear force up to a period of 3 days. The sensory acceptability was found to be higher than that of the control bread for emulsifiers, and lower for enzyme at a concentration higher than 10 g/kg flour. PRACTICAL APPLICATIONS Flat bread is normally consumed fresh, but the staling phenomenon starts immediately after baking this kind of bread. Today, large-scale production and increased consumer demands for high-quality bread with long shelf life have created the need for functional food additives such as emulsifiers and , -amylase enzyme. Incorporation of emulsifiers and enzyme decreased the hardness of Taftoon bread. Emulsifiers and , -amylase enzyme enhanced the flat bread dough quality. The sensory acceptability also improved with the addition of emulsifiers. Optimizing the amount of emulsifiers and enzyme required for reduction of bread hardness is vital because the quality and price of the final product depend on this parameter. [source] ,-Carotene-Loaded Nanostructured Lipid CarriersJOURNAL OF FOOD SCIENCE, Issue 2 2008A. Hentschel ABSTRACT:, Nanostructured lipid carriers (NLC) technology was used to disperse hydrophobic ,-carotene in an aqueous phase. NLC are lipid nanoparticles with a particle matrix consisting of a blend of a liquid and solid lipid. They were produced by melting the lipid blend at 80 °C and dispersing it into a hot emulsifier solution. The aim of this study was to extend the limited knowledge of melt-emulsified lipidic colloids in food systems and to evaluate the feasibility for further applications as functional ingredient in beverages. Physical stability of the NLC suspension was examined at 2 different storage temperatures by measuring the particle size with photon correlation spectroscopy (PCS) and laser diffractometry (LD). All particles containing sufficient amounts of emulsifier were smaller than 1 ,m (LD diameter 100%) at a mean particle size of around 0.3 ,m (LD) for 9 wk at 20 °C and at least 30 wk at 4 to 8 ° C. Differential scanning calorimetry (DSC) was used to study the solid state of the lipids both in the ,-carotene loaded PGMS and in the NLC particles. Propylene glycol monostearate (PGMS) when dispersed as NLC recrystallized up to 98% during storage time. Within the regarded period of 7 mo no polymorph transitions were observed. Furthermore, stability of the ,-carotene in water dependent on NLC concentration and tocopherol content was measured photospectrometrically to get an estimation of the behavior of NLC in beverages. [source] Capillary Flow and Rheology Measurements on Chocolate Crumb/Sunflower Oil MixturesJOURNAL OF FOOD SCIENCE, Issue 9 2004S. Carbonell ABSTRACT: Rates of penetration of sunflower oil into beds of 3 types of chocolate crumb have been measured and the results analyzed using the Washburn-Rideal theory. The data show that the rates are a function of both the specific surface area of the crumb particles and their surface composition. Addition of an emulsifier to the oil reduces the penetration rate into the crumb made with full-cream milk powder, whereas for crumbs containing skimmed-milk powder, rates go through a maximum with increase of emulsifier concentration. Rheological data for dispersions of crumb in oil were fitted to the Casson equation. An inverse correlation was found between penetration rates and Casson yield values. [source] Casein Hydrolysate Fractions Act as Emulsifiers in Process CheeseJOURNAL OF FOOD SCIENCE, Issue 2 2002H.S. Kwak ABSTRACT: Degrees of hydrolysis and emulsifying activity of casein hydrolysates were the highest at 4 h hydrolysis. The oil-off values of the mixture of hydrolysate (H) or supernatant (S) and traditional emulsifier (T) were not significantly different from the control made with traditional emulsifier, except for S + T = 3:1. Two other samples made with hydrolysate or supernatant only (H or S) showed higher oil-off value than the others (p < 0.05). In flavor property, no difference was found between samples made with traditional emulsifier and those made with the mixture of hydrolysate or supernatant at the ratio of 3 to 1. Therefore, these results indicated that a mixture of the hydrolysate or supernatant and traditional emulsifier might replace a traditional emulsifier in process cheese manufacturing. [source] An environmentally benign room temperature aqueous homo- and copolymerization of styrene and methylmethacrylate catalyzed by [Cp2TiCl2]/NaBPh4JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 23 2009Sudip K. De Abstract [Cp2TiCl2] has been found to be an effective precatalyst for room temperature aqueous homo- and copolymerization of methyl methacrylate and styrene in the presence of a cocatalyst, NaBPh4 and an emulsifier, sodium n -dodecyl sulfate. The polymers obtained are of high molecular weight with low molecular weight distribution. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 6496,6503, 2009 [source] Particle formation under monomer-starved conditions in the semibatch emulsion polymerization of styrene.JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 22 2001Abstract Particle formation and particle growth compete in the course of an emulsion polymerization reaction. Any variation in the rate of particle growth, therefore, will result in an opposite effect on the rate of particle formation. The particle formation in a semibatch emulsion polymerization of styrene under monomer-starved conditions was studied. The semibatch emulsion polymerization reactions were started by the monomer being fed at a low rate to a reaction vessel containing deionized water, an emulsifier, and an initiator. The number of polymer particles increased with a decreasing monomer feed rate. A much larger number of particles (within 1,2 orders of magnitude) than that generally expected from a conventional batch emulsion polymerization was obtained. The results showed a higher dependence of the number of polymer particles on the emulsifier and initiator concentrations compared with that for a batch emulsion polymerization. The size distribution of the particles was characterized by a positive skewness due to the declining rate of the growth of particles during the nucleation stage. A routine for monomer partitioning among the polymer phase, the aqueous phase, and micelles was developed. The results showed that particle formation most likely occurred under monomer-starved conditions. A small average radical number was obtained because of the formation of a large number of polymer particles, so the kinetics of the system could be explained by a zero,one system. The particle size distribution of the latexes broadened with time as a result of stochastic broadening associated with zero,one systems. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3940,3952, 2001 [source] Role of grafting in the emulsion polymerization of vinyl acetate with poly(vinyl alcohol) as an emulsifier.JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 20 2001Abstract The role of grafting in particle nucleation during the emulsion polymerization of vinyl acetate with partially hydrolyzed poly(vinyl alcohol) (PVA) as an emulsifier and potassium persulfate as an initiator was investigated. The polymerizations were carried out in batch with a low solids (10%) recipe. An automated reaction calorimeter (Mettler RC1) was used for the direct monitoring of the kinetics of emulsion polymerizations with three medium molecular weight PVAs differing in their degrees of blockiness (Poval 217EE > 217E > 217). Smith,Ewart case 1 kinetics (average number of free radicals per particle < 0.5) were followed in all cases, and no constant rate in interval II was observed. Contrary to what was expected, a nonlinear relationship was observed between the rate of polymerization (Rp) and the number of particles (Np). At Rp max,Np (217E) > Np (217EE) > Np (217), and the final Np was independent of the degree of blockiness of PVA. The particle size distributions were broad (particle diameter = 20,100 nm) and bimodal. On the basis of these data, we concluded that particle nucleation was continuous and was accompanied by extensive limited aggregation during the particle growth stages. The evolution of the amounts of grafted PVA and poly(vinyl acetate) (PVAc) were determined in polymerizations employing the two PVAs differing the most in blockiness (Poval 217EE and 217). The grafted PVAc followed similar profiles, increasing with conversion, particularly near the end of the two reactions. The amounts of grafted PVAc were about the same in the final latexes (37,39%). In contrast, the grafting of PVA was nearly complete by the time monomer droplets had disappeared in each reaction (25% conversion). However, the extent of grafting differed significantly, with the blockier PVA having about one-third the grafting of the more random PVA (,10% vs ,30%). In these low solids recipes, grafting appeared to be primarily a solution event, occurring predominantly in the aqueous phase and not at the particle/water interface, as was previously speculated. The PVAc grafts grew until the molecules became water-insoluble and precipitated, forming polymer particles. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3633,3654, 2001 [source] MODELING OF TEXTURE EVOLUTION OF CAKES DURING STORAGEJOURNAL OF TEXTURE STUDIES, Issue 1 2010MANUEL GÓMEZ ABSTRACT The aim of this work is to model the variation of texture parameters in cakes during staling. The evolution was studied in layer cakes (cake A) and sponge cakes (cake B). The effect of storage temperature and the addition of fiber, xanthan gum (cake A) and emulsifier (cake B) were also studied. The best model to adjust the texture parameters variation during storage in both kinds of cakes was square root x (y = a + b * x1/2), except for firmness and springiness in cakes B. Firmness and springiness were adjusted the best to the linear model. In the model, y stood for the textural parameters and x for the time. a and b were related to the initial value of the studied parameter and with its change over time respectively. In both kinds of cakes, A and B, the firmness and gumminess increased, and the cohesiveness, springiness and resilience decreased, as the storage time increased. The increase in the storage temperature and the addition of fiber minimized the firmness changes in both kinds of cakes. PRACTICAL APPLICATIONS This methodology simplifies the study of cake textural parameters during storage and the result interpretation. Moreover, the correlation analysis has demonstrated that the number of textural parameters of cakes to study can be reduced. [source] Synthesis and Characterization of Magnetic NanocontainersJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2008Christos Tapeinos Magnetic hollow spheres were synthesized through a two-step process and were evaluated by Fourier transform infrared spectroscopy, scanning electron microscopy, super quantum interference device, vibrating sample magnetometry and Mössbauer spectroscopy methods. First, polystyrene spheres (PS) were produced using emulsion polymerization. Second, the PS spheres were coated via the sol,gel method to form an iron oxide layer. The size of the PS spheres was controlled by the concentration of the monomer (styrene), the initiator (potassium persulfate), and the emulsifier (sodium dodecylsulfate). The sol,gel coatings were prepared by controlled hydrolysis of aqueous solutions of FeCl3 in the presence of PS latex, polyvinylpyrrolidone, and hydrochloric acid. The composite was treated in air to burn off the PS latex. Temperature treatments were optimized after extensive differential thermal analysis and thermo gravimetric analysis characterization of the samples. Treatments under hydrogen atmosphere at various temperatures gave control over the formation and extend of magnetic phases in the nanocontainers such as a Fe, hematite (Fe2O3), and magnetite (Fe3O4). The size of the containers ranged between 300 and 400 nm. [source] Influence of lipase and/or emulsifier addition on the ileal and faecal nutrient digestibility in growing pigs fed diets containing 4% animal fat,JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 12 2004NA Dierick Abstract Information on the addition of lipase and/or emulsifiers to less digestible or saturated fat sources, such as tallow or other animal fats, used in swine feeding is very limited. Therefore, in a 4 × 4 Latin square design, the effects of adding lipase (0.05% L5, microbial source) and/or an emulsifier (0.3% Lysoforte) on the apparent ileal (AID) and faecal (AFD) digestibility of the main nutrients and fatty acids in particular were studied with four ileal-cannulated growing pigs (female, initial live weight 20 kg) fed diets containing barley/soybean meal supplemented with 4% animal fat. The fat source contained 35% saturated (S) and 65% unsaturated (U) fatty acids. All diets were free of antibacterial substances (antibiotics, copper sulphate or zinc oxide beyond requirements), in order to avoid interactions between the parameters studied and the gut flora. Lipase addition did not affect the AID or AFD of fat. However, the digestibility of minor fatty acids (C6:0, C14:0) was significantly improved by lipase at both ileal and faecal level. On the other hand, lipase supplementation (P < 0.05) improved the AID of dry matter (DM) and energy as well as the AFD of DM, organic matter (OM), crude protein (CP), ash and energy. Addition of an emulsifier did not have any significant influence on the AID or AFD of fat, while the AID values of DM, OM, CP and energy as well as the AFD values of DM, OM, CP and ash were significantly (P < 0.05) improved. Adding lipase in combination with an emulsifier to the diets decreased (P < 0.05) the AID and AFD of fat, with minor effects on the AID and AFD of the non-fat components of the diet. The lack of improvement in the digestion of fat by exogenous lipase and/or emulsifier may be related to the rather high U/S ratio (0.65:0.35) of the animal fat source used and to the mode of incorporation of the emulsifier (no pre-dispersion in the fat source). Furthermore, during the trial the diets, stored at room temperature, showed a steady increase in their content of free fatty acids (to more than 700 g kg,1 fat), due to endogenous lipase activity, leaving less room for upgrading the digestion of animal fat by exogenous lipase and/or emulsifier. Copyright © 2004 Society of Chemical Industry [source] Characterization of Methyl Methacrylate Grafting onto Preirradiated Biodegradable Lignocellulose Fiber by , -RadiationMACROMOLECULAR BIOSCIENCE, Issue 1 2005Ferdous Khan Abstract Summary: Gamma-radiation-induced graft copolymerization of methyl methacrylate onto natural lignocellulose (jute) fiber was carried out by the preirradiation method in an aqueous medium by using octylphenoxy-polyethoxyethanol as an emulsifier. The different factors that influenced the graft copolymer reaction process were investigated. In the case of radiation-dose-dependent grafting, samples irradiated in the presence of air produced up to 73% graft weight compared to 53% obtained in the case of irradiation in a nitrogen environment. By assuming Arrhenius reaction kinetics, the activation energy (Ea) of the grafting reaction process was evaluated for different reaction temperatures. Moreover, the graft copolymer reaction was controlled by incorporating a homopolymer-inhibiting agent and three different chain-transfer agents in the reaction medium. The mechanical and thermal properties of jute fiber ,as received' and jute- graft -poly(methyl methacrylate) were also investigated. The results showed that the percentage of grafting with jute fiber has a significant effect on the properties. The kinetic parameters were evaluated from TGA thermograms by using Broido's method in the temperature range 240,350,°C. Scanning electron micrographs show that the structural changes on the surface of jute fibers were induced by graft copolymerization of methyl methacrylate monomer. Fiber-fiber surface friction was measured in terms of the average maximum load and the kinetic friction. SEM of jute- graft -poly(methyl methacrylate). [source] Synthesis of Polypyrrole Using Benzoyl Peroxide as a Novel Oxidizing AgentMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 3 2006Chandrasekaran Saravanan Abstract Summary: Benzoyl peroxide is used as an oxidizing agent for the first time in the synthesis of conducting polypyrrole. Synthesis of polypyrrole is commonly performed by chemical oxidative polymerization using water-soluble oxidizing agents. In this work, polypyrrole was prepared using organic solvent-soluble benzoyl peroxide as an oxidizing agent in the presence of p -toluenesulfonic acid (p -TSA) and sodium lauryl sulfate (SLS) surfactant via the inverted-emulsion-polymerization technique. During polymerization, SLS is converted to dodecyl hydrogensulfate (DHS) and incorporated on to polypyrrole along with p -TSA dopant, indicating SLS is acting as emulsifier as well as dopant. The influence of synthesis conditions such as the duration of the reaction, the temperature, the concentration of the reactants, etc., on the properties of polypyrrole was investigated to determine the optimum conditions for the synthesis of polypyrrole salt. Polypyrrole was obtained in a reaction time of 1 h with high yield (154 wt.-% with respect to pyrrole used) and good conductivity (2 S,·,cm,1). The conductivity of polypyrrole-salt was found to be nearly the same even after seven months of storage at ambient temperature (1.7 S,·,cm,1). [source] Amphiphilic polyelectrolyte for stabilization of multiple emulsions,POLYMER INTERNATIONAL, Issue 4 2003Fanny Michaut Abstract Multiple emulsions are complex thermodynamically unstable systems where both types of emulsion coexist. We investigated the stability behaviour of water-in-oil-in-water (W/O/W) emulsions formulated with a hydrophobically modified poly(sodium acrylate) emulsifier at the outer interface and a monomeric surfactant (span 80) at the inner interface. Their stability was tested through release kinetics of a marker (NaCl) initially encapsulated in the aqueous droplets, and by rheology. Slow release rates and remarkably long shelf-life were obtained compared to typical multiple emulsions stabilized by two commonly used surfactants (span 80 and tween 20). In addition, we prepared stable highly concentrated multiple emulsions. Their rheological behaviour indicated that the internal interface was essentially covered with span 80. Thus, transportation of the polymer across the oil phase is limited, which in turn explains, at least partially, the stability improvement in the presence of the polymeric emulsifier. Finally, the long lifetime of the emulsions allowed study by diffusing wave spectroscopy of the interactions between the droplets and the globule surface which are important for understanding the destruction mechanisms of multiple emulsions. © 2003 Society of Chemical Industry [source] Kinetics of acrylate emulsion polymerization containing hydrophilic hydroxyl monomer in the presence of nano-SiO2 particlesPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 3 2009Cai-Li Yu Abstract Kinetics of acrylate emulsion polymerization containing hydrophilic hydroxyethyl methacrylate (HEMA) and acrylic acid (AA) in the presence of nano-SiO2 were investigated. The influence of temperature, emulsifier level, hydroxyl monomer content and the level of nano-SiO2 on monomer conversion, polymerization rate (Rp), and the particle size was studied. The results showed that the presence of nano-SiO2 increased the Rp when the level was below 5% but decreased when the level was above 7.5%, the more levels, the more seriously. As the temperature and emulsifier levels increased, and the presence of hydroxyl monomer, the Rp increased. The active energy of the system was 142.01,kJ/mol and the relationship of Rp and the concentration of emulsifier (E) was Rp,,,[E]0.38. The mean particle size increased, particle size distribution became broader as the nano-SiO2 levels increased. Copyright © 2008 John Wiley & Sons, Ltd. [source] Microencapsulation of n -Eicosane as Energy Storage MaterialCHINESE JOURNAL OF CHEMISTRY, Issue 5 2004Xiao-Zheng Lan Abstract For heat energy storage application, polyurea microcapsules containing phase change material, n -eicosane, were synthesized by using interfacial polymerization method with toluene-2,4-diisocyanate (TDI) and diethylenetriamine (DETA) as monomers in an emulsion system. Poly(ethylene glycol)octyl-phenyl ether (OP), a nonionic surfactant, was the emulsifier for the system. The experimental result indicates that TDI was reacted with DETA in a mass ratio of 3 to 1. FT-IR spectra confirm the formation of wall material, polyurea, from the two monomers, TDI and DETA. Encapsulation efficiency of n -eicosane is about 75%. Microcapsule of n -eicosane melts at a temperature close to that of n -eicosane, while its stored heat energy varies with core material n -eicosane when wall material fixed. Thermo-gravimetric analysis shows that core material n -eicosane, micro- n -eicosane and wall material polyurea can withstand temperatures up to 130, 170 and 250 °C, respectively. [source] Endogenous microflora in turbid virgin olive oils and the physicochemical characteristics of these oilsEUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 2 2008Anastasios Koidis Abstract Cloudy olive oil, the fresh olive juice, is an intermediate form before full precipitation of freshly produced olive oil. Some consumers prefer it because they consider it as more natural and less processed. The cloudy form can persist for several months. The oil is a sort of dispersion/suspension system which can be also described as a micro-emulsion/suspension. Water micro-droplets were found to have a size ranging from 1 to 5,µm. Cloudiness is due to the low water content and the presence of natural emulsifiers in the oil. The suspension is formed by solid particles (5,60,µm) deriving from the olive fruit. They are present in small amounts (12,460,mg/kg oil). In the newly produced olive oil, containing 0.17,0.49% water, a number of microorganisms of different types (bacteria, yeasts, moulds) were found to survive, but at very low concentrations (<3,log,cfu/mL oil). They originate from the exterior of the fruit (epiphytic microflora) and their presence is considered natural. Their enzyme activities do not seem to affect the quality of the final product. [source] Kinetic study of the reaction of dimethyl carbonate with trialkylaminesINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 4 2010Duane E. Weisshaar Quaternary ammonium compounds are produced worldwide in hundreds of millions of pound volume annually for a plethora of end-uses from fabric-care formulations to asphalt emulsifiers, typically from nongreen alkylating reagents. The kinetics of a reaction employing dimethyl carbonate (DMC) as a green alkylating agent was investigated using three trialkylamines (tributylamine, trihexylamine, and trioctylamine) at several temperatures. Arrhenius and Eyring analysis of the data showed that values of Ea (79 kJ/mol), ,H, (75 kJ/mol), and ,S, (220 J/(mol K)) were the same for all three amine reactants, consistent with a report that Ea is independent of alkyl chain length when the chain length is greater than three carbons. Although rates are significantly slower with DMC than with other alkylating reagents, the resulting methyl carbonate anion has advantages for clean anion metathesis, which is important for some applications, especially those involving ionic liquids. © 2010 Wiley Periodicals, Inc. Int J Chem Kinet 42: 221,225, 2010 [source] The rheological behaviour of low fat soy-based salad dressingINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 12 2008Chi Zhang Summary Low fat soy-based salad dressings were formulated with different oil levels (3%, 13% and 23%) and emulsifiers (whey protein concentrate, soy-lecithin and sodium caseinate) using either blender or ultra-turrax (UT) homogeniser. Results showed that the rheological behaviour of these samples were highly dependent on the oil content, emulsifiers and blending methods. The UT method produced samples with better viscosity and have droplet size of 2,100 ,m. Samples containing higher oil level have higher viscosity, smaller droplet size, larger G, and G, values. All samples show a shear-thinning effect and larger G, than G,, indicating the elastic nature of the samples. A quantity Q(t)% was applied to estimate the elasticity and the values were found to be in the range 22.8,85.2%. G, and G, were found to decrease with increased temperature. However, tan , increased slightly with temperature; the values ranged from 0.2 to 0.4 at 5 °C to 0.3,0.5 at 25 °C. Current results demonstrated that the formulated samples have good stability compared with commercial products. [source] | |||||||||||||||||||