Preparation of Silicone Emulsion Defoamer with Easy Separation of Magnetic Hydrophobic Nanoparticles

To prepare lyophobic magnetic nanoparticles (LMNs) with core/shell structure to be applied in silicone emulsion defoamer, magnetic nanoparticles covered with silica (MNS) were prepared in a one-step process from FeCl3 · 6H2O, FeCl2 · 4H2O and tetraethyl orthosilicate and then modified with poly (methylhydrosiloxane). X-ray powder diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared spectroscope (FTIR), thermogravimetric analysis (TGA), and contact angle tests were performed to characterize the nano-particles, and the droplets of the defoamer emulsion were observed with a microscope. The foam breaking and foam inhibition properties of the defoamer and the magnetic separation of the particles were observed and recorded by a camera. It was found that the silicone emulsion defoamer exhibited good foam breaking and foam inhibition properties for foaming systems with anionic, cationic and non-ionic surfactants, respectively. The solid particles in the defoamer could be easily separated from the defoamed systems by a magnet.

Double-segregated multiwalled carbon nanotube/silicone composites with large electrical to thermal conductivity ratios via in-situ silicone emulsion polymerization

Polymer composites with a high electrical conductivity ( σ) to thermal conductivity ( k) ratio have been intensively investigated in recent years. While highly conductive materials, such as metallic fillers or conducting polymers, were used to enhance σ, microstructural engineering was used to decrease k by forming porous structures, such as aerogels or 3D networks. These structures, however, were mechanically vulnerable and could only have limited applications. In this study, multiwalled carbon nanotube /silicone composites with a high σ/k ratio were developed by forming a double-segregated multiwalled carbon nanotube network in the porous body of the composites. The unique microstructure of the composites was created by a novel fabrication process: layer-by-layer deposition with in-situ polymerization of silicone emulsion particles dispersed in a water solvent. This novel process yielded very thick films, >200 µm, with high σ/k values, ∼2 × 104 (S/m)/(W/m·K). These high σ/k composites can be used for various applications, such as resistive heating elements, thermoelectric materials, and wearable thermotherapy.

Palm leaf sheath fiber extraction, bleaching, softening and characterization of effect of softening on longitudinal view, tensile strength and elongation of the fiber

Sheath of Palm tree indigenous to Ethiopia was used to extract fiber by chemical degumming using 80 % sodium hydroxide; bleached, softened and characterized the physical properties of the extracted fibers before and after softening. The extracted fibers were subjected to bleaching using 30% H2O2 bleaching agent to remove the reddish yellow color of the extracted. By mass; 203.4g of decorticated dried palm tree sheath was subjected to chemical degumming. Degumming of the raw decorticated palm sheath with 20% sodium hydroxide solution and 5% wetting agent was carried out. The degumming process was incubated at the temperature 120˚C for 2hours. To remove residual gummy substances which are already dissolved and left on the fibers; the fibers were washed by warm water and dried. It's found that 28.87% degummed fiber was extracted. After bleaching the degummed fibers; the fibers were washed to remove residual H2O2 from the fibers. The bleached fibers were treated by silicone emulsion to soften the fibers. Finally the fibers were dried and their Characteristics (before and after softening); Longitudinal view, Tensile strength at break and Elongation at break characterized. Also moisture regain (R %) and moisture content (W %) of the softened fibers were characterized and found as 12.65 and 11.23% respectively.

Effect of Emulsifier on the Structure and Properties of Waterborne Silicone Antifouling Coating

Three-component waterborne silicone antifouling coatings, which could cured at room temperature, were prepared, respectively, with cationic (stearyl trimethyl ammonium bromide) or anionic (sodium dodecyl benzene sulfonate) silicone emulsion as a film-forming substance, γ-methacryloxypropyltrimethoxysilane as a curing agent and dibutyltin dilaurate as a catalyst. The effect of emulsifier on the structure and properties of silicone coating was studied. The results showed that the coating with cationic silicone emulsion had high crosslinking density, and its surface is smooth. The surface of the coating prepared by the anionic silicone emulsion is rough. Emulsifier type had no obvious effect on the surface free energy of the waterborne silicone coating. The coatings have the characteristics of low surface energy and excellent bacterial desorption properties. Stearyl trimethyl ammonium bromide in the cured coating can reduce the adhesion of marine bacteria on the coating surface. Both the emulsifiers can inhibit the activity of Navicula Tenera. The waterborne silicone coating prepared by cationic silicone emulsion has better comprehensive mechanical properties and antifouling performance.

Anti-acid Corrosion Property of Concrete Improved by Microstructure Optimizing

To enhance the performance of anti-acid erosion, silica fume, silicon nitride, organic silicone emulsion agent and fly ash ceramsite are all mixed into concrete as admixture. The acid corrosion environment is simulated by laboratory test. Compressive strength of concrete with different curing ages are tested. Compressive strength and pore distribution of concrete dipping in sulphate and in hydrochloride for 90d are tested. The result shows that concrete with additional materials has better anti-acid corrode performance than the common one. The compressive strength of concrete with additional materials is higher than the common concrete. The pore distribution curve of the concrete with additional materials can keep steady no matter in sulphate or in hydrochloride. This kind of concrete with high anti-acid corrosion durability has been used in the piles construction of the bridges which is surrounded by acid soil and play an important role in enhancing the durability of the bridge.