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The development of polymer composites, considering the environmental issues, is aimed for minimizing the industrial content. New environmental-friendly nanocomposites, based on silicone rubber matrix and different concentrations of natural fiber/chromium oxide fillers, are prepared for the first time. The microstructural analysis confirms the successful obtaining of microfibers after treatment and chromium oxide nanoparticles and the formation of the final composite. The nanocomposites achieved improved physical and mechanical properties due to the dual effect of both fillers and attachment to the matrix. The 1% optimized nanocomposite achieved the highest modulus, dielectric properties, hydrophobicity, and surface stability. The effect of exposure to weathering conditions was studied. The characterization sentence asserts the preparation of a novel silicone rubber nanocomposite with improved properties, along with the environmental impact, regarding the dual effect of natural fiber waste and chromium oxide nanoparticles. [ABSTRACT FROM AUTHOR]

The characteristics of the shape memory effect of a silicone rubber–titanium nickelide composite material under bending deformation have been studied. It is shown that the critical deformation (), upon reaching which 0.2% of unrecoverable deformation is accumulated in the composite, can reach 36–38% (at = 9% in a reinforcing filler made of titanium nickelide). A method for calculating the mechanical behavior of a composite under bending deformation is proposed. [ABSTRACT FROM AUTHOR]

Despite the fact that Pyrovatex is widely used as a commercial flame-retardant, the release of toxic formaldehyde remains a serious problem. Fluorine-based compounds, on the other hand, have been employed to impart hydrophobic textile surfaces, although they are exceedingly costly and poisonous. Based on those difficulties, we describe a simple one-step method for coating electrically conductive cotton-nickel (Cot-Ni) blend fabric providing flame-retardant and water-repellent characteristics. A nickel ribbon was firstly bent around a cotton yarn as a core, and then woven into an electrically conductive Cot-Ni blend fabric, which was created by weaving the cotton-nikel hybrid threads with regular cotton yarns. The conductive fabric was coated with a composite consisting of silicone rubber (RTV) and ammonium polyphosphate (APP). The strong binding of RTV with both APP and cotton fibres increased the flame-retardant action of cotton, according to the findings. As a result, varied concentrations of APP were used in the composite to show that only 100 g/l of APP combined with RTV improved the fire-retardancy. Depending on the concentration of APP, distinct hierarchical morphologies appeared on the surface of the coated Cot-Ni fabrics. RTV also improved the hydrophobic character of the blend surface. Measurements of air permeability, surface roughness, and stiffness were used to investigate the comfort qualities of the coated Cot-Ni blends. Eventually, those multifunctional (Cot-Ni)/RTV-APP textiles might be used in a variety of applications, such as grain storage containers, car seat mats, and firefighters' uniforms. [ABSTRACT FROM AUTHOR]

A study aimed to prepare cellulose-based hydrophobic, lightweight, and flame retardant foam composites. Cellulose was activated by phosphoric acid followed by blending with dolomite clay of different loading ratios. Gelatin/tannin as an adhesive system was used as a binder. A solution of the environmentally friendly silicone rubber (RTV) was applied onto foam samples via spray-coating to improve their water repealing performance, which was explored by investigating both of water contacting angle and wettability time of the coated foam samples. Flammability characteristics, thermal decomposition, surface morphology, and chemical structure of treated and untreated foams were investigated by flammability test, thermogravimetric analysis, scanning electron microscopy, X-ray diffraction, and Fourier-transform infrared. The fire retardancy of foam composites was optimized at low and medium loading of dolomite. Also, the addition of RTV improved the hydrophobicity of composites maintained the fire retardancy of composites with medium loading. [ABSTRACT FROM AUTHOR]

Co0.5Zn0.5Fe2O4 ferrite nanoparticles were prepared using sol–gel citrate method. (Silicone Rubber/CoZn nanoferrite) composite samples with ferrite loadings (5, 8, 11, 14 and 17) phr were synthesized. XRD, TEM and FTIR techniques were used to investigate the structure and morphology of ferrite while SEM and FTIR techniques were utilized to study the structure of the rubber/nanoferrite composites. The effect of frequency (50 Hz to 5 MHz), nanoferrite load and temperature (30 to 195 °C) on the real and imaginary parts of the electric permittivity (ε′ and ε′′) showed an increase up to ferrite load up to 8 phr sample. Results were explained in the light of Debye theory of dielectrics using some models based on Clausius–Mossotti equation. The mechanical parameters (tensile strength, elongation at break and Young's modulus) were enhanced up to ferrite load (8 phr) which reflects the improvement of the performance of these composite samples. [ABSTRACT FROM AUTHOR]

In this paper, we proposed a new pneumatic actuation method inspired from a soft robot, which could drive the multi-stable carbon fiber-reinforced polymer (CFRP) structure transition among five stable configurations under air pressure. Multi-stable structure was manufactured by the carbon fiber prepreg laid in asymmetrical and anti-symmetric layup methods and stacked at the joint during the preparation process according to the designed scheme. In experiments, multi-stable structures with two different fibers layups were prepared to study the snap-through behaviors. The snap-through process of two kinds of multi-stable structures was investigated by experiment. The parameters used to characterize efficiency of the pneumatic actuator actuating the multi-stable structures, including air pressure and snap time, were measured. The influence of the pneumatic actuator on the curvature of multi-stable structures was discussed by comparing the shape characteristic of multi-stable structures with or without pneumatic actuation, and it showed pneumatic actuator has little effect to the structure. The results demonstrated that the proposed pneumatic actuation could be used to drive multi-stable morphing structure flexibly. The combination of multi-stable laminates develops the function of multiple point bending and shape retention of pneumatic actuation. [ABSTRACT FROM AUTHOR]

We report on a simple technique for the production of mechanically durable water-repellent layer on viscose fibers via spray-coating of a lanolin-silicon rubber solution in petroleum ether. Depending on the silicon rubber solution concentration, it was achievable to gain surfaces with hierarchical morphology. Extracted lanolin was admixed with a mixture of a room temperature vulcanizing silicon rubber and petroleum ether to afford the silicon rubber-lanolin formulation, which was applied successfully onto viscose fabrics employing spray-coat procedure. The surface characteristics of the spray-coated viscose fibers were studied by scanning electron microscope, energy dispersive X-ray analysis, and static water contact and sliding angle measurements. The alteration in the chemical composition of viscose-treated fabric was studied using Fourier-transform infrared spectroscopy. The wetting behavior was found to be a function of silicon rubber concentration in ether solution affording coatings with high static water contact angle and low sliding angle values. The treated viscose fabric exhibited excellent ultraviolet protection and enhanced hydrophobicity without adverse effect on its inherent physico-mechanical properties. The comfort characteristics of spray-coated viscose fibers were also evaluated by studying their air-permeability and stiffness. The results displayed durable water-repellent properties of the treated viscose, introducing a good opportunity for a large-scale manufacture of water-repellent textiles for a diversity of industrial purposes. [ABSTRACT FROM AUTHOR]

Shock wave properties of porous specimens made on the basis of matrices composed of inert and chemically active media (silicon rubber and emulsion, which is an aqueous solution of ammonium nitrate with mineral oil and emulsifier) are studied. The porosity of the specimens is generated by using a filler composed of glass microspheres. The wave velocity profiles are measured by a VISAR laser Doppler interferometer. It is shown that the shock compressibility of porous silicon rubber at pressures below 0.1 GPa displays an anomalous behavior, resulting in smearing of the compression pulse front propagating over the specimen. In the emulsion matrices without microspheres, there are no noticeable chemical transformations up to the pressure of 15 GPa. Addition of microspheres drastically decreases the threshold of chemical reaction initiation and leads to the formation of a steady detonation wave. [ABSTRACT FROM AUTHOR]

Porous asymmetric polyethersulfone (PES) hollow fiber membrane was fabricated via dry/wet spinning process. The spinning dope consisted of 18 wt.% PES in N-methyl-2-pyrrolidone (NMP) solvent. Distilled water was used as bore fluid to make hollow fiber membrane without inner skin layers. Then, a skin layer consisting of poly (4-vinyl pyridine), PVP, silicon rubber PDMS and silica nanoparticles (nano-SiO) was transferred to the PES substrate surface by means of a dip coating method, leading to a nanocomposite hollow fiber membrane. Investigation of the cross-section of the prepared membranes via scanning electronic microscopy (SEM) revealed a good adhesion between the top dense layer and the PES substrate. Moreover, tensile strength and ultimate elongation of the pristine membrane were increased 2.3 and 5 times, respectively, when the PVP/PDMS/nano-SiO coating was formed on its outer surface. Finally, according to the results of gas permeation tests, the prepared nanocomposite membrane, with a CO/CH selectivity of 45 and CO permeance of 102 GPU would be an attractive candidate for applications such as natural gas purification and control of anthropogenic carbon dioxide emissions. [ABSTRACT FROM AUTHOR]

In this paper, both the displacement field and the strain field of silicon rubbers during the tearing process are investigated by means of 3D digital speckle correlation method. First, the speckle pattern is artificially sprayed on the surface of the standard silicon rubber sample. Second, a series of deformation images of the rubber tearing specimen are recorded during the tearing process, which indicates the failure evolution and different failure patterns. Finally, full-field three dimensional displacements and strain information are obtained for providing the development of a strain concentration zone in rubber material. [ABSTRACT FROM AUTHOR]