Papers by Keyword: Silicone

Abstract: In several sports, such as martial arts, point scoring depends on applied impact. Embedded sensors in wearable protection devices help to quantify the impact intensity. In parallel, there is a growing interest in developing products with a reduced ecological footprint, using natural materials such as cork. Considered a light, resilient, flexible, and hypo-allergenic material, cork has been proving to be a material with interesting impact absorption properties to be integrated into personal protection, as is the case with helmets and vests. Silicon rubber has also been proposed as an alternative elastomer material with adequate sealing and electrical isolation properties, while resistant to ageing and impact. Since injuries occur more frequently in lower extremities, presented work is part of a project that aims to explore the interest of replacing foams and synthetic leathers usually applied in foot protections with smaller CO₂ footprint materials while increasing their impact absorption properties. At this stage, a part of a protection prototype consisting of a plate made from natural cork, coated with silicone rubber protection containing embedded force sensors, was studied. The objective is to explore the potential of such materials to replace those conventionally applied in commercial foot protections. Firstly, the adhesion between imprinted silicon and cork was confirmed through peeling tests. Then, considering the opportunity of inserting sensors within the additive manufacturing of the parts, different silicone coating configurations and sensor placements were tested regarding their impact performance. Comparison between impact absorption performance was carried out using an impact test device, assessing sandwich composite performance and force sensing reading accuracy. Silicone printability during the robocasting extrusion technique demonstrated to facilitate the sensor placement without requiring deposition path modification. It showed to be an easy way to manipulate the sensor position within the composite layers and, by that, to modify its impact performance. This is an important contribution to the main goal of the undergoing project, which is to completely replace commercial materials with this new sandwich composite.

Abstract: Maxillofacial prosthesis is a non-invasive procedure to replace damaged or lost facial tissue structures. Extraoral maxillofacial prosthesis to resemble facial skin tissue is made of silicone. The addition of fillers and pigments to silicone has been done to improve its physical and mechanical properties while maintaining its biocompatibility. This study aims to evaluate the cytotoxicity of nano silica filler and intrinsic pigment additives in clean grade silicone as an alternative material for maxillofacial prosthesis. Thirty clean grade silicone samples were divided into 6 treatment groups: 1 group of silicone without any additives and 5 groups of silicone with addition of intrinsic pigment and nano silica filler with concentration of 0%, 1%, 2%, 3% and 6%. Cytotoxicity was assessed by MTT assay against 3T3L1 fibroblasts. The average absorbance value for all treatment groups was 0,941-1,105, which was lower than the control group. The post hoc test showed that only the 6% of nano silica and intrinsic pigment additive group did not differ from the control group. The addition of silica nano filler and intrinsic pigment to silicone did not cause toxicity to 3T3L1 cells. The cytotoxicity of nano silica is determined by its particle size and concentration. The use of intrinsic pigments produces compounds that are less reactive to genetic material. In conclusion, the addition of nano silica filler and intrinsic pigment to clean grade silicone as an alternative maxillofacial prosthesis is nontoxic. The addition of 6% nano silica filler and intrinsic pigment to clean grade silicone showed the best cell viability.

Abstract: The utilization of geothermal silica as the silica source to synthesize silicone as lithium-ion battery anode component was comprehensively studied. Silicone conversion was performed using magnesiothermic reduction at a temperature of 650 °C for 7 h. The applied Mg:SiO₂ mole ratio on magnesiothermic reduction were 1.6:1, 2:1, and 2.5:1. The purification treatments of silicone product were conducted using two stages of acid leaching using HCl and a mixture of HF and acetic acid. In lithium-ion battery anode preparation, the ratio of Si to graphite employed 100:0; 90:10; 50:50; 10:90; and 0:100. The best yield and the conversion of silicone were 26.46% for the yield and 85.60% for the conversion by using 2:1 of Mg:SiO₂ ratio. In the purification treatments, silicone yield of 29.45% with silicone purity of 58.9% was achieved using HCl, and silicone yield of 25.97% with silicone purity of 98% was achieved by using mixed solution of HF and acetic acid. The best battery performance in term of specific capacity was found by applying Si:graphite ratio of 100:0 with the value of first cycle of 358.5 mAh/g in this research. These findings present the reliability and feasibility of the geothermal solid waste and acid leaching treatments to generate the high quality of silicone for lithium-ion battery anode component.

Abstract: VPCS with [Si-CH₂-CH₂-Si] structure were synthesized through hydrosilylation reaction of divinyldimethylsilane and diphenylsilane. VPCS were mixed with additive liquid PMPS silicone rubber and VPCS/PMPS based ablative composites were also prepared. VPCS play an important role in improving the thermal stability of PMPS. The 10% weight loss of VPCS/PMPS is 530.6°C, and T_max is at 601.3°C, 43°C and 48°C higher than PMPS. Anti-ablation fillers have great important on composites. VPCS/PMPS/ZrB2 showed higher mechanical properties and ablative resistance, which is accordance with the results of SEM morphology observation.

Abstract: Enhancement of the room temperature vulcanization silicone rubber (RTV) tracking resistance with various filler loadings of synthesized wollastonite against electrical surface tracking was prepared. The X-ray diffraction (XRD), Scanning electron microscope (SEM), and X-ray fluorescent (XRF) techniques were involved in characterizing the synthesized substances. The test method IEC-60587 standard was employed to evaluate the surface tracking resistance. The results obtained from the XRF technique confirmed that the raw materials could be synthesized for wollastonite, while the XRD and SEM techniques revealed the formation of wollastonite (CaSiO₃) associated with gehlenite (Ca₂Al₂SiO₇). Moreover, it was found that the electrical surface tracking resistance of composite insulation takes a long time to track when the filler loading is increased more than 5 phr.

Abstract: Dielectric elastomer actuator (DEA) is a compact device that consists of stretchable electrodes and elastomers. This device is energy efficient in performance and holds great promise in the development of soft actuators. DEAs performance relies significantly on the mechanical properties of its elastomers. This present study focuses on evaluating the soft material made of Sylgard 184 as the elastomers for DEAs. Sylgard 184 is a silicone elastomer that comes with two main parts (elastomers and its curing agent). A specific mixing ratio between elastomers and curing agent is essential to produce solid and reliable silicone elastomer. The recommended ratio for the elastomer solution was ten parts for the elastomers and one part for the curing agent (10:1). Producing softer elastomers was possible by reducing the curing agent. However, the performance of the material was unknown. We performed a series of cyclic tensile tests to understand the mechanical characteristic of the elastomer made of Sylgard 184. The result shows that reducing the curing agent did not have a significant effect on its cyclic performance. Furthermore, the use of a 30:1 ratio in the application of DEAs and deformable linear actuator indicates stable performance for both devices.

Abstract: In this paper we have developed a simple and inexpensive method to fabricate cilia-like silicone rubber-ferrofluid composite cantilever beams. The technique described can generate highly reproducible arrays of these microcantilevers ranging from 1 mm to 0.4 mm in diameter. We use a laser cutter to create moulds for the cantilevers making it a low cost and reliable process. The iron particles from the ferrofluid can uniformly dispersed, randomly arranged or isolated on the tip of the cantilever. Cantilevers with 400 μm diameter and up to 10 mm length are tested with low magnetic field of 15mT. We obtained maximum deflection of 82.5^o at 44 mT magnetic field.

Abstract: According to modern standards, all courtyard, school and public playgrounds on which gaming equipment is installed must undergo tests of shock absorption of the surface under and around the equipment to prevent serious injuries to the child. In this regard, widely spread coatings on the basis of rubber chips. However, they not only do not meet the aesthetic requirements, but can also worsen the environmental situation when operating indoors. The paper describes a method for producing composites from wood flour and a silicone binder. The effect of wood meal content on the water absorption of composites as well as the effect of silicone content on the density of the results of the research showed that an increase in the content of wood flour significantly increases the water absorption of the resulting composite, that the composite material obtained with the addition of filler from wood meal, the values ​​of the maximum and minimum elastic moment increased, since the presence of fillers imparts a restriction on the deformation of the composite, and, consequently, the composite becomes harder and harder. As a result of the studies carried out, it can be concluded that the use of silicone as binder and shredded wood waste as a filler makes it possible to obtain good quality elastic flooring with high aesthetic, operational and environmental properties.

Abstract: The dimensional stability of dental impression materials is one of the variables that contribute to the accuracy or to the inexactitude of dentures. The rheological properties of several dental impression materials were determined by amplitude and frequency sweep tests. Deformation, storage modulus G’, loss modulus G” and complex viscosity η^* were studied for each sample. Moreover, the texture, the stability of the shape, the capacity of distribution on different surfaces and the stability to storage for a long period of time were investigated. All these samples, characterized by a gel structure with G’>G”, are suitable as impression materials. Irreversible hydro-colloids) may be used for different kind of impressions because of their fidelity and elasticity; they also present medium time elasticity and may be easily prepared.

Abstract: A silicone based self-deicing coating was prepared by blending of silicone solution and organics-coated NaCl deicing additive. The effects of deicing additive content and coating amount on freezing point of coating surface and adhesion force between ice and coating were investigated. The deicing durability of self-deicing coating was evaluated by immersion test. And the influence of silicone based self-deicing coating on friction coefficient and structure depth of asphalt pavement was researched. The experimental results showed that freezing point of coating surface and adhesion force between ice and coating decreased with the increase of the organics-coated NaCl content, freezing point and adhesion force of the self-deicing coating with 6wt.% organics-coated NaCl were-5.2°C and 24.5 N respectively. Immersion test results showed that the deicing performance had only a small reduction after immersion in water for 3 days,which indicated the self-deicing coating had good deicing durability. Moreover, silicone based self-deicing coating had slight influence on friction coefficient and structure depth of asphalt pavement due to the good permeability of silicone solution. The friction coefficient of asphalt pavement decreased by 10.4%, and the structure depth decreased by 6.1% when the amount of the self-deicing coating was 300 g/m².