Addition Of Stearic Acid Research Articles

Characterisation of gelatin–fatty acid emulsion films based on blue shark ( Prionace glauca) skin gelatin

Incorporation of fatty acids (stearic and oleic) into edible films based on blue shark ( Prionace glauca) skin gelatin was investigated to modify properties such as water vapour barrier and flexibility due to their hydrophobicity and plasticizing effect, respectively. Addition of stearic acid from 0% to 100% of protein concentration in the film-forming solution considerably decreased water vapour permeability of gelatin–fatty acid emulsion films compared to addition of oleic acid at the same fatty acid concentration. Increasing concentrations of both fatty acids decreased tensile strength, but increased elongation at break due to their plasticizing effect. At the same concentration, oleic acid gave a greater plasticizing effect than did stearic acid. On the other hand, transparency of the gelatin–stearic acid emulsion film was lower than that of the gelatin–oleic acid emulsion film. Faster stirring speed of homogenisation improved properties of only the gelatin–stearic acid emulsion film.

Effects of stearic acid on synthesis of nanocomposite WC–MgO powders by mechanical alloying

The effects of stearic acid as a process control agent (PCA) on the synthesis of WC–MgO by mechanical alloying have been investigated. 0–2.0 wt% of stearic acid is added into the mixture of WO3, Mg, and graphite powders in high-energy planetary ball milling experiments, and the as-milled powders are characterized by XRD and TEM. Results show that the mechanochemical reaction among WO3, Mg, and graphite to form WC–MgO can be changed from a mechanically induced self-propagating reaction (MSR) to a gradual reaction by the addition of stearic acid in the range from 1.2 to 1.8 wt%, when other milling parameters are maintained at the same level. It has also been found that with the addition of stearic acid, the crystallite and particle size of WC–MgO powders can be refined, the homogeneity of particle size can be improved and the powder yield can be increased.

Method of manufacturing nonwovens by electrospinning from polymer melts

A unit for electrospinning of polymer melts was created. Nonwovens with an average fibre diameter of 0.5-20 μm were obtained from a melt of both pure polyamide 6 and its blends with stearic acid and oleic acid additives in the amount of 2-10 wt. % were obtained. Addition of 10% SF decreases the average diameter of the fibres obtained by 40 times due to a decrease in the viscosity of the melt by 60 times.

시멘트 재료의 수밀성에 대한 스테아르산의 영향

It is well known that the properties of concrete such as the compressive strength, water permeability, water tightness and durability are affected by micro-structure in hardened cement paste. Especially, for durability of concrete, watertightness of cementitious materials is the most critical property among various properties. Recently, many types of materials as organic and/or inorganic materials are used for watertightness of concrete. In this study, The effect of Stearic Acid at 0.5 wt%~3.0 wt% adding ratios on the hydration and watertightness property of cement were investigated. And we also discussed the changing of microstructure in hardened cement paste by addition of Stearic Acid. Cement paste with Stearic Acid showed improvement of watertightness by reducing of cement total pore volume and decomposition of Stearic Acid.

The role of fatty acids in the mechanical properties of beeswax

Beeswax is a mixture of many organic compounds, including hydrocarbons, wax esters, and fatty acids. Because fatty acids in beeswax also serve as social signals, we explored the functional signif- icance of the fatty acids. The removal of the fatty acids from beeswax results in diminished yield stress, resilience, stiffness, and proportional limit stress of beeswax samples. Addition of stearic acid to beeswax enhances all of these properties except resilience. Artificial wax mixtures show a positive correlation be- tween the amount of stearic acid in the wax mixture and yield stress. Unsaturated fatty acids found in beeswax behave similarly, with respect to their effects on the mechanical properties of artificial wax mix- tures. Fatty acid concentration showed significant variation among colonies, particularly among the unsat- urated fatty acids. We interpret these findings with respect to the mechanical properties of beeswax and the role of fatty acids in communication among bees. Apis mellifera / wax / fatty acid / yield stress / stiffness

Madera plástica de polipropileno reforzado con harina de madera: efecto de la adición de agentes compatibilizantes provenientes de recursos renovables

Compósitos de polipropileno reciclado (PPr) con harina de madera de la espécie Pinus elliottii (PIE) fueron desarrollados utilizando aceite de soya, ácido esteárico, ácido caprílico y polipropileno graftizado con ácido itacónico (PPgAI) como agentes compatibilizantes. Los compósitos fueron procesados en extrusora de doble husillo co-rotante y posteriormente moldados por inyección. Los materiales fueron caracterizados a través de ensayos mecánicos, termogravimétricos, morfológicos, físicos y por ángulo de contacto. Los resultados de los ensayos mecánicos demostraron que el aceite de soya actuó como plastificante y redujo las propiedades mecánicas de los compósitos. Por otro lado, la adición de ácido esteárico, ácido caprílico y PPgAI generó en un aumento de la resistencia a flexión de 8, 20 y 29%, respectivamente, comparado al compósito sin compatibilizante. El compósito desarrollado con el agente compatibilizante comúnmente utilizado, el polipropileno graftizado con anhidrido maleico (PPgAM), presentó un aumento de 35% en la resistencia a la flexión. Resultados del análisis termogravimétrica (TGA), del compósito de PPr con aceite de soya presentó una reducción de su estabilidad térmica en 3% de pérdida de masa, lo que puede estar asociado a la mayor cantidad de oxígeno en su estructura molecular, lo que facilita mayor movilidad de las cadenas con el aumento de la temperatura y que pueden acelerar el proceso de degradación. En el caso de los compósitos con ácido caprílico y PPgAI mostraron un aumento superior a 10°C en la temperatura de 3% de perda de masa cuando comparados al compósito sin compatibilizante, indicando un aumento de la estabilidad térmica de estos compósitos. Los resultados de los análisis de microscopia electrónica de Barrido comprobaron la mayor interacción entre las fases (harina de madera y la matriz de PPr) para los compósitos desarrollados con ácido caprílico y PPgAI; y en relación a los resultados del ángulo de contacto de los materiales, mostraron que la incorporación del agente compatibilizante graftizado originó un aumento de la energía superficial de la matriz polimérica promoviendo una mejor interacción con la carga vegetal (hidrofílica).

Cryotolerance of Bovine Blastocysts is Affected by Oocyte Maturation in Media Containing Palmitic or Stearic Acid

In this study, non-esterified fatty acids (NEFAs) were added during in vitro maturation at concentrations measured previously in follicular fluid (FF) of high-producing dairy cows in a negative energy status to evaluate their subsequent effect on the embryos cryotolerance. Oocytes were matured for 24 h in serum-free media with or without (negative control) the addition of NEFAs dissolved in ethanol or ethanol alone (positive control). Matured oocytes were fertilized and cultured for 7 days in synthetic oviduct fluid medium supplemented with 5% FCS. Embryos that had at least reached the blastocyst stage were vitrified by open pulled straw (OPS) vitrification. Addition of palmitic (C16 : 0) or stearic acid (C18 : 0) during oocyte maturation had significant negative effects on embryo cryotolerance, whereas ethanol or oleic acid (C18 : 1) had no effect. These in vitro results suggest that high NEFA concentrations in FF during a period of negative energy balance in high-yielding dairy cows can have carry-over effects on embryo quality.

Preparation and bioactivity of sol-gel macroporous bioactive glass

Bioactive glass is well known for its ability of bone regeneration, and sol-gel bioactive glass has many advantages compared with melt-derived bioactive glass. 3-D scaffold prepared by the sol-gel method is a promising substrate material for bone tissue engineering and large-scale bone repair. Porous sol-gel glass in the CaO-SiO 2-P 2O 5 system with macropores larger than 100 μm was prepared by the addition of stearic acid as a pore former. The diameter of the pore created by the pore former varied from 100 to 300 μm. The formation of a hydroxyapatite layer on the glass was analyzed by studying the surface of the porous glass by scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and Raman spectra after they had been immersed in simulated body fluid (SBF) for some time, and the porous glass shows good bioactivity.

Flow and void formation in powder injection moulding feedstocks made with PEG/PMMA binders Part 1 – Experimental observations

Mixtures of 94 wt-% tungsten carbide (WC) and 6 wt-% cobalt (Co) powders with different particle sizes have been formed with binders composed of polyethyleneglycol (PEG) and polymethylmethacrylate (PMMA), in some cases with the addition of stearic acid (SA) as a lubricant. The presence of voids has had to be invoked to explain why, when the same moulding conditions were used, the as moulded and as leached densities varied with binder composition and in some cases, why the former were lower than expected from the proportions of binder components and solids used to prepare the feedstocks. For a given nominal binder content (vol.-%), calculated on the assumption of zero voidage, and using constant moulding conditions, it appears that the actual voidage tended to decrease as PMMA progressively replaced PEG, and to increase as SA was introduced to replace PEG. The former change to the binder composition should, with constant binder content and moulding conditions, increase the apparent viscosity of the feedstock, while the latter should reduce it. A slip band model is postulated which allows flow behaviour and void formation to be explained qualitatively. This is further developed in Part 2 of this paper. Data from previous studies using PEG/PMMA binders with stainless steel powders are included as these can now be given a qualitative explanation with the slip band model.

Enhanced high-field performance in Fe-sheathed MgB2 tapes using inexpensive stearic acid additives

High performance Fe-cladded MgB2 taps were prepared by the in situ powder-in-tube method utilizing very cheap stearic acid (C18H36O2) as dopants. The amount of stearic acid was varied from 0 to 30 wt%. We found that a significant enhancement of Jc, Hirr, and Hc2 in comparison with undoped samples was easily achieved. At 4.2 K, the transport Jc for the best doped tapes (10 wt%) reached 2 × 104 A/cm2 at 10 T and 3.7 × 103 A/cm2 at 14 T, respectively, an order of magnitude higher than for the pure tapes. In particular, at 20 K, the irreversibility field of the 10 wt% doped tape was around 10 T, which is comparable to the upper critical field of the commercial NbTi at 4.2 K. The results demonstrate great potential of MgB2 tapes for superconducting magnets.

Role of process control agent on synthesis and consolidation behavior of nano-crystalline copper produced by mechano-chemical route

Nano-crystalline copper was synthesized by mechano-chemical reduction of Cu 2 O with carbon. Influence of stearic acid addition as a process control agent (PCA) on characteristics of synthesized and consolidated copper samples was investigated. The structural evolution and morphology of powders were evaluated using XRD and SEM, respectively. It was found that the nano-crystalline Cu formed after 35 h of milling and addition of stearic acid prolonged the process. On the other hand, the use of stearic acid in final stages of the process prevented excessive cold welding of ultra fine Cu particles during milling. In fact, it successfully inhibited the formation of coarse Cu particles and eventually decreased the crystallite size of the product to 19 nm. The hardness of sintered Cu sample increased due to the reduction of mean crystallite size.

Filmes compostos de gelatina, triacetina, ácido esteárico ou capróico: efeito do pH e da adição de surfactantes sobre a funcionalidade dos filmes

The development of biofilms has grown considering the possibility of partial substitution of plastic materials which are not biodegradable. Proteins and polysaccharides have been used to produce films with good mechanical properties. However, films produced with these materials present a high permeability in water vapor. An alternative to improve the water vapor barrier of films is to incorporate hydrophobic substances (stearic and caproic fatty acids) in the composition of the filmogenic solution, however this incorporation does not occur homogeneously. Thus, to improve the incorporation of hydrophobic substances in the protein matrix of the film, surfactants (SDS and Tween 80) were added. They are compounds that improve the interaction between the protein and the fatty acids, producing a less heterogeneous filmogenic matrix. The effect of pH was also studied, with the purpose of observing if it influences the homogeneity of the filmogenic matrix. The addition of stearic acid to the gelatin-based films was more efficient in reducing the water vapor permeability than the caproic acid. Adding surfactant SDS reduced water vapor permeability of both films, with stearic acid or caproic acid. Adjusting the pH to the films with no surfactants produced more homogeneous matrices.

Investigation of porous glass-ceramic materials using stearic acid additives

Investigation of porous glass-ceramic materials using stearic acid additives

Poly(Lactic-co-glycolic Acid) Microspheres for the Controlled Release of Huperzine A: In Vitro and in Vivo Studies and the Application in the Treatment of the Impaired Memory of Mice

Huperzine A loaded poly(D,L-lactic-co-glycolic acid) (PLGA) microspheres were prepared by an oil/water (o/w) solvent evaporation technique. With a decrease of the ratio of o/w from 1 : 100 to 1 : 50, the encapsulation efficiency was reduced about 4%. Increasing the PVA concentration from 0.5 to 2% reduced the percentage encapsulation efficiency of huperzine A from 60.7 to 47.4% and the particle size of microspheres from 84.2 to 26.2 microm. The addition of stearic acid improved the encapsulation efficiency, but also accelerated the in vitro release of hupezine A from microspheres. After i.m. administration of huperzine A loaded microspheres in mice, huperzine A was sustained released from the PLGA microspheres up to 12 d with a low initial burst. Passive avoidance test of mice showed that the microspheres formulation offered an improved therapeutic efficiency in the treatment of the impaired memory of the mice superior to injection gastric (i.g.) administration of huperzine A suspension at the same dose, whose therapeutic efficiency was similar as that of a 50% reduced dose of the microspheres formulation.

Effect of the addition of fatty acids on rice starch properties

The effect of the addition of the two fatty acids (stearic and linoleic acid) on starch pasting, thermal properties and the leaching of amylose during the gelatinization process are presented. The addition of stearic acid (C18:0) at 1.0% level (w/w, on the basis of starch) significantly changed starch pasting characteristics in peak viscosity (P < 0.05), breakdown (P < 0.001) and time to peak viscosity (P < 0.001) as measured by RVA. In contrast, the addition of linoleic acid (C18:2) showed less impact on the three RVA parameters. Thermal studies with DSC suggested that the addition of both fatty acids did not significantly influence the starch gelatinization behaviour as reflected in peak width and enthalpy but there was a decrease in peak temperature. However, the addition of the saturated fatty acid produced a significant decrease in the retrogradation endotherm (P < 0.01) compared to that of native starch. It is suggested that the saturated fatty acid complexes with amylose and is preferentially introduced into the starch granule. The double bond in the linoleic acid apparently hinders complexation. After complexation, hydrophobicity was further enhanced with the content of amylose in the hot-water soluble fraction being significantly reduced (P < 0.01) as determined by HPLC.

Method for determination of critical powder loading for powder–binder processing

Powder–binder processing technologies are commonly used to form near finished shape parts for high performance metals and ceramics. For successful powder–binder processing, it is necessary to estimate the critical powder loading to optimise the powder loading of powder–binder mixture. A new method for determination of critical powder loading by a pycnometer is proposed. The principles of the new method are expounded. The critical powder loading is distinguished from the maximum powder loading. The measuring experiments for metal powder are carried out, and the new method is validated by comparing with the existing method. It is revealed that the new method is simple, convenient, fast and accurate. The new method is applied to determine the critical powder loading of ceramic powders in both micro and nano sizes. It is found that the critical powder loading of the nano powder is lower than that of the micro powder, and the addition of stearic acid to paraffin wax binder can improve the critical powder loading.

Amaranthus cruentusFlour Edible Films: Influence of Stearic Acid Addition, Plasticizer Concentration, and Emulsion Stirring Speed on Water Vapor Permeability and Mechanical Properties

Films forming solutions composed of Amaranth (Amaranthus cruentus) flour (4.0 g/100 mL), stearic acid (5-15 g/100 g of flour), and glycerol (25-35 g/100 g of flour) were prepared by an emulsification process, with varying stirring speed values (6640-13360 rpm). The influence of these parameters (stearic acid and glycerol concentrations and stirring speed) on the water vapor barrier and mechanical properties of films was evaluated using the response surface methodology (RSM). Other characterizations, including microstructure, water solubility, and oxygen permeability, were performed in optimized films. According to statistical analysis results, the optimized conditions corresponded to 10 g of stearic acid/100 g of flour, 26 g of glycerol/100 g of flour, and a stirring speed of 12 000 rpm. The films produced under these conditions exhibited superior mechanical properties (2.5 N puncture force, 2.6 MPa tensile strength, and 148% elongation at break) in comparison to those of other protein and polysaccharide composite films, low solubility (15.2%), and optimal barrier properties (WVP of 8.9 x 10(- 11) g m(- 1) s(- 1) Pa(- 1) and oxygen permeability of 2.36 x 10(- 13) cm3 m(-1) s(-1) Pa(-1)).

Oxidation kinetics of soybean oil in the presence of monoolein, stearic acid and iron

The oxidation kinetics of soybean oil containing 1% (w/w) monoolein, 1% (w/w) stearic acid and 0.005% (w/w) iron was evaluated at 55 °C under light. The oxidation rates were determined by oxygen consumption and peroxide formation. Addition of monoolein, stearic acid or iron to the soybean oil accelerated the rate of lipid oxidation during the storage. Monoolein increased the rate of oxygen consumption whereas iron increased the rate of peroxide decomposition. The reaction order of soybean oil was found to fit first-order kinetics and was not affected by the addition of monoolein, stearic acid or iron. The rate constants were 2.55 × 10 −2, 2.94 × 10 −2, 2.91 × 10 −2, 3.02 × 10 −2 h −1, and the half-lives were 27.18, 23.58, 23.82, 22.95 h for the soybean oil, monoolein, stearic acid and iron samples, respectively.

Effect of the unsaturation degree and concentration of fatty acids on the properties of WPI-based edible films

The incorporation of lipids into hydrophilic protein films allows the modification of their barrier properties, improving its commercial application as preservation medium on different foods. The main objective of this study was to develop films from Whey Protein Isolate (WPI) together with saturated and unsaturated fatty acids and to determine the effect of concentration and unsaturation degree on surface tension of the coating solution and on water vapor permeability (WVP), mechanical properties (tensile strength and elongation at break), and opacity, of the films. The results obtained showed that surface tension was significantly decreased by adding unsaturated fatty acids (oleic and linoleic acid), whereas the greatest effect on WVP reduction was achieved with stearic acid. The addition of stearic acid resulted in a decrease of elongation and an increase of tension strength; however unsaturated fatty acid content did not modify the elongation and slightly reduce a tensile strength.

Tailoring of pore size in mesoporous silica with stearic ACID and PVP

Mesoporous silica was prepared using tetrathoxysilane (TEOS), cetadecyltrimethylammonium bromide (CTAB), aqueous ammonia, acetone and water as silica source, template agent, precipitator and solvent respectively. Stearic acid and polyvinylpyrrolidone (PVP) were employed as additional templates to tailor the pore size in the resultant porous silica. BET, SAXRD and SEM analyses were used to characterize the surface area, pore size, pore structure, pore regularity and morphology of the sample. BET measurement results showed that PVP could increase the surface area but diminish the pore size while stearic acid could decrease the surface area but enlarge the pore size. SAXRD analysis indicated that more additional template introduction gave rise to less order-structured products. All these various results could be attributed to the differently modified CTAB micelles involving stearic acid and PVP addition.