Papers by Keyword: Surfactant

Abstract: Typically, the emollient effect of the vegetable oil has attributed to its usefulness in skin care preparation. The present study aims to prepare the oil in water emulsion cream containing virgin coconut oil (CO) comprisinghydrophilic and lipophilic surfactants (Tween 80 and Span 80). Stability of creams containing CO upon addition of peppermint oil (PO), co-surfactant (Solutol HS 15, ST), solubilizer (benzyl benzoate, BB) was investigated after the temperature cycling. All prepared creams showed the shear thinning flow behavior. Addition of BB gave the lowest viscosity while that comprising ST exhibited the higher viscosity. The highest viscosity formula was the CO andPO containing cream. The particle size determined using light scattering particle analyzer revealed that the mean particle size of all prepared creamswaslower than 35.56 ± 0.62 µm. The homogenous dispersion of oil globules in emulsion was evident, especially, in formulation II (CO) and IV (COand ST). Although the temperature cycling influenced more or less on the compact structure of gel network of cream, the decrement of viscositywasminimal and not much different for cream containing CO and ST (formulation IV). In addition, the mean particle size wasthe smallest for formulation II (CO) which was followed by formulation IV (CO and ST). There wasthe homogenous dispersion of oil globules in formulation II and IV after temperature cycling. All of the above finding was beneficial for employingCO as the oil phase in producing cream such as the foot massage cream where the addition of ST provided the better stability for the prepared cream containing CO.

Abstract: Optimization of complex shrinkage-reducing additives (further, SRA’s), consisting of ordinary portland cement clinker (further, OPC clinker), salt-electrolyte and surfactants, is provided for prevention of steel reinforcement corrosion due to shrinkage mitigation in alkali-activated slag cement (further, AASC) fine concrete. Modification of AASC by SRA included 0.3 % sodium lignosulphonate, 0.15 % sodium gluconate, 1.4 – 2.0 % NaNO₃ and 6.5 - 7.7 % OPC clinker (by mass of granulated blast furnace slag) provides shrinkage reduction from 0.984 up to 0.560 – 0.605 mm/m (t=202 °С, R.H.=65 %). Unlike, SRA presented by the mentioned system with 1.50 - 1.59 % Na₂SO₄ and 4.0 - 4.65 % OPC clinker causes shrinkage mitigation from down to 0.625 - 0.640 mm/m. In addition, SRA with 1.80 - 2.05 % Na₃PO₄ and 4.0 - 4.6 % OPC clinker minimizes shrinkage to 0.713 - 0.700 mm/m. Shrinkage mitigation in modified AASC fine concrete is explained by less water, higher crystallinity of hydrated phases as well as by formation of minamiit (Na,Ca_0.5)Al₃(SO₄)₂(OH)₆, calcium hydronitroaluminate ЗСаО∙А1₂О₃∙Са (NO₃)₂∙10Н₂О and calcium hydroxylapatite Са₁₀(РО₄)₆(ОН)₂ crystals versus salt-electrolyte, i.e. Na₂SO₄, NaNO₃ and Na₃PO₄ agreeably. The 28 day compressive strength of modified AASC fine concrete is not less than the reference one (48.0 - 56.0 МPа).

Abstract: This paper emphasises the effect of the surfactant in the PMEDM process. The preparation of nanofluid is done by mixing and sonicating thoroughly into the deionised water is discussed. The effect of varying the graphene nanopowder concentration into the dielectric is also discussed. Also, the effect of surfactant SDS and CTAB in the machining process is elaborated at 0.1 and 0.2g per 800ml concentration. MRR improved by 21.27% and roughness by 18.91% at 0.2g and 8µs, 2A and 50V in 800ml deionised water. SDS provide better MRR and low roughness compared to CTAB at higher peak current and higher pulse on time Simultaneously, the addition of surfactant into the dielectric medium reduces the performance of the EDM process. The MRR varies from 21mg/min at 0g graphene to 45mg/min at 0.2g and then 31.81mg/min at 0.2g with 0.1g SDS, 43mg/min at 0.2g SDS, 28.33mg/min at 0.1g CTAB and 30mg/min at 0.2g CTAB. Debris size also varies with the input parameters.

Abstract: A new seed-mediated growth technique for synthesizing gold nanorods (NRs) by using H₂O₂ as the weak reducer in the presence of a binary surfactant mixture is reported. Gold NRs prepared at different amounts of H₂O₂ and the gold seeds solution were characterized by transmission electron microscopy (TEM) and visible–near infrared spectroscopy. Gold NRs with tunable aspect ratio from 4.5 to 7 can be obtained and the corresponding longitudinal plasmonic wavelength of the produced gold NRs are tunable from 810 to 1140 nm. This method provides a new pathway for synthesis of gold NRs with a wide range of longitudinal plasmonic peaks, which have potential applications in optoelectronics and biomedicine.

Abstract: Stainless steel will become one of the main substrate materials for flexible large-scale displays. As the substrate of the flexible displays, the biggest problem of stainless steel is that the surface roughness is too large. It is necessary to polish the surface of stainless steel with ultra-precision. Chemical mechanical polishing (CMP) technology will be one of the most practical processing technologies to make the surface of stainless steel ultra-smooth and damage-free. In this paper, the material removal rate (MRR) and surface roughness were studied based on the hydrogen peroxide oxidant and ferric chloride oxidant with different surfactants in chemical mechanical polishing (CMP) slurry by experiments. The results show that it can obtain the maximum of the MRR and the optimal surface quality when using 0.04 wt% sodium hexadecyl sulfate as the surfactant of the hydrogen peroxide-oxalic acid based polishing slurry and when using 0.2 wt% nonylphenol ethoxylate or 0.8 wt% OP-10 emulsifier as the surfactant of the of ferric chloride-oxalic acid based polishing slurry. The results of this study can provide a reference for further research on the chemical mechanical polishing of stainless steel.

Abstract: Polypyrrole nanoparticles prepared in the presence and absence of polyvinylpyrrolidone (PPy/PVP) fine black powders have been synthesized as adsorbents for the removal of copper Cu (Ⅱ) and iron Fe (Ⅲ) ions from aqueous solution. PPy and PPy/PVP were chemically prepared by using ferric chloride as an oxidant, and distillate water as a solvent with and without polyvinylpyrrolidone as a surfactant. The prepared PPy and PPy/PVP adsorbents were characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Brunauer–Emmett–Teller (BET) surface area, and Fourier Transform Infrared spectroscopy (FTIR). The results display BET surface area equals 7.88 and 21.93 for PPy and PPy/PVP, respectively. The data also shows that PPy/PVP acts as flawless adsorbent for the removal of copper and iron ions from aqueous solution with sequestration percentage of 90% and 83% in 2 hours respectively.

Abstract: Y-doped barium cerate-zirconate ceramic oxide is proven to be a competent material as an electrolyte with high proton conductivity as well as chemical and mechanical stabilities in carbon dioxide and water vapour atmospheres. This ceramic oxide requires high processing temperature which will results in the increase of particle/grain size. Hence, modification on the synthesis route has been studied in reducing the particle/grain size of the ceramic by lowering the calcination temperature. In this work, BaCe_0.54Zr_0.36Y_0.1O_2.95 (BCZY) powder was synthesized with addition of surfactant (Brij-97) through an established modified sol-gel route. Single BCZY perovskite phase was successfully obtained at calcination temperature of 950°C which was lower than our previous study (T=1100°C). The prepared sample was made into pellet by a dry pressing technique with diameter, d=13 mm and thickness, t~2 mm and then subjected to a two-step sintering method prior to morphological and electrical measurements. Impedance measurement was carried out at intermediate temperatures (500-800°C) using an Electrochemical Impedance Spectroscopy (EIS) in wet nitrogen atmosphere. Impedance spectrum was analysed to obtain the behaviour of grain core and grain boundary responses by a fitting procedure using a brick-layer model. Scanning electron microscope (SEM) analysis of fractured pellet revealed that BCZY prepared with the assisted of Brij-97 exhibited dense, homogenous and less agglomerate grain with grain size around 88 nm, which may explain the enhancement in the total conductivity of the BCZY electrolyte.

Abstract: In this research, titanium dioxide (TiO₂) nanoparticles were immobilized into polyvinyl alcohol (PVA) matrix without and with surfactants via solution casting film combined with thermal treatment method. The dispersion and distribution of TiO₂ nanoparticles presented by scanning electron microscopy (SEM) showed the uniform distribution of TiO₂ nanoparticles in PVA matrix with surfactant. Fourier-transform infrared spectroscopy (FTIR) showed increasing intensity peak at 560-800 cm^-1 corresponding to Ti-O stretching vibration indicating interaction between PVA and TiO₂ after thermal treatment. X-ray diffraction (XRD) result showed peak of PVA crystal structure due to the thermal treatment, and the addition of surfactant could decrease the average crystallite size of TiO₂ in PVA/TiO₂ nanocomposite films. Photocatalytic activity was determined from the film efficiency on removal of methylene blue (MB) under ultraviolet (UV). The results showed the greater MB removal efficiency of the PVA/TiO₂ nanocomposite films with surfactant and thermal treatment than those without surfactant and thermal treatment.

Abstract: In-situ silica nanoparticles with ammonium laurate surfactant in natural rubber latex composites were characterized to describe the reinforcement mechanism in enhanced mechanical properties. In-situ sol-gel method was introduced to generate silica nanoparticles in natural rubber latex using a mole ratio of water-to-TEOS of 28.9 stirring at room temperature for 24 hours. The addition and effect of adding ammonium laurate surfactant for enhancing dispersion and compatibility between silica nanoparticles and rubber matrix was also studied. The natural rubber latex was then vulcanized by electron beam radiation at 200 kGy. The silica content in rubber composites made in-situ, was analyzed by TGA, showed an increase from 3.08 phr to 8.92 phr, corresponding to addition of TEOS amounts of 10 phr to 30 phr, respectively. The dispersion of silica nanoparticles in rubber matrix with ammonium laurate surfactant was improved and exhibited less aggregation than rubber composites absent of ammonium laurate surfactant as evidenced by SEM-EDX. The increase of silica content in rubber composites exhibited lower swelling ratio and higher crosslink density when compared with neat natural rubber. Also, the modulus at 100% and 300% strain also increased with increasing silica nanoparticles incorporation in contrast to tensile strength.

Abstract: The peculiarity of alkali-activated slag cements (further, AASC’s) is increased proper deformations, which can cause increased cracking and reduced durability of structure. The paper is devoted to manage AASC’s proper deformations. The main task was to determine the composition of complex additives (further, CA’s) in system «ordinary portland cement (further, OPC) clinker - mineral compound of different anionic type - surfactant» in presence of sodium metasilicate (further, MS) to affect on hydrated AASC performance while ensuring effective structure of artificial stone by criterion of shrinkage deformations. Comparative analysis of hydrated cement systems "OPC clinker - MS", "OPC clinker - mineral compound - MS" and "OPC clinker - mineral compound - MS - surfactant" showed that the greatest effect on reduction of proper deformations occurs when the mineral compounds relate to electrolytes, i.e. Na₂SO₄ and NaNO₃. Hydrated system is characterized by expansion (+0,062 mm/m) in presence of Na₂SO₄. Almost no shrinkage is supplied by application of NaNO₃ (-0,062 mm/m). The obtained CA’s were tested in AASC. CA in the system “OPC clinker - NaNO₃ - surfactant” provides the initial setting 43 min, the end - 65 min with accelerated strength. Investigated AASC can be classified as non-shrinking cement. This phenomena is ensured by increasing density, homogeneity and monolithicity of hydrosilicate formations, as well as due to formation of hydroaluminosilicate structures with different morphology by inclusion of nitrate anions.