Papers by Keyword: Elastomer

Abstract: Investigating the electrowetting behavior of droplets on structured surfaces provides insight in developing electric-driven microfluidic substrates and membranes. Microstructures and patterns inspired by nature could result in interestingly unique wettability and electrowetting phenomenon. In this work, the electrowetting of water droplets on a superhydrophobic leaf of desmodium (Desmodium spp) and its elastomeric replica were explored. An open electrowetting system consisted of an optical camera, platinum wire, and DC power supply with water microdroplets as test liquid was used to investigate the electrowetting behavior on the leaf. Soft lithography using elastomer was used to produce replica of the leaves. Natural cell-like patterns, including central protrusions and microhairs, contribute to the leaf's superhydrophobic properties (contact angle > 150°). The negative copy of the natural patterns generated via soft lithography produced a microstructured elastomeric film, showing a static contact angle of ~128°. Optical microscope images of the elastomeric copy revealed the successful duplication of the leaf’s surface features. Subsequent electrowetting experiments demonstrated a contact angle reduction of up to 15° and 9.5° for the natural leaf and its elastomeric replica, respectively. A pronounced electrowetting-driven droplet motion was observed on the leaf while droplet pinning was noted in the elastomer. These results offer new insights into the electrowetting phenomenon of microstructured surfaces for potential self-cleaning and water-trapping applications.

Abstract: In order to develop sustainable materials for a variety of industries, hybrid polymer composites reinforced with natural fibers are emerging as a critical option. The various forms of hybrid composites and the employment of various polymers—such as thermoplastics, thermosets, and elastomers—when paired with natural fibers are the main topics of this narrative theoretical review. The article examines the applications of various composites in industries such consumer products, construction, automotive, and aerospace, providing insights into how polymer choice affects a composite's applicability for a given application. Through an examination of recent advancements in hybrid composite design and polymer utilization, this analysis offers a thorough grasp of the present trends and potential applications of these materials in promoting sustainable engineering practices.

Abstract: This study focuses on synthesizing and characterizing a semi-Interpenetrating Network (semi-IPN) elastomeric hydrogel comprising natural rubber (NR) and polyethylene glycol methacrylate (PEGMA) for efficient removal of Methylene Blue (MB) dye from aqueous solutions. The impact of varying PEGMA/NR ratios (100/0 to 0/100) was investigated. SEM images displayed a porous and uniform structure with interconnected pores of different sizes. FTIR analysis confirmed the formation of a semi-IPN structure, showcasing functional groups in both NR and PEGMA. Adsorption studies revealed the hydrogel's efficacy in MB dye removal, achieving a maximum adsorption capacity of 6536 mg/g at a PEGMA/NR ratio of 90/10. UV-vis spectroscopy validated the reduction in MB concentration post-exposure to the hydrogel. These findings highlight the cationic ionic nature of the PEGMA/NR semi-IPN elastomeric hydrogel as a promising adsorbent for MB dye removal in wastewater applications, particularly in industrial wastewater treatment.

Abstract: The work presents the results of testing new eco-oils in elastomeric materials based on nitrile butadiene rubber (NBR). The influence of eco-oils grade and content on the rubber mixes based on NBR 2665 processing was studied. It is established that Phytonorman 212 acts as a technologically active additive that improves the rheological and relaxation characteristics of rubber mixes. Phytonorman 213 acts as an activator of the vulcanization process when eco-oils content is 2 phr. To maintain the complex of physical, mechanical and working performances, so as to prevent the slowdown of the vulcanization process at 7 phr eco-oil content it is recommended to adjust vulcanizing group component content and filler grade.

Abstract: The article discusses the synthesis and development of the direction of vulcanization of elastomers with quinol esters of p-benzoquinone dioxime. The concept of a critical temperature T_cr which denotes noticeability of the vulcanization process of unsaturated rubbers (with k=1×10^-6, s^-1) is introduced. Noted the increased vulcanizational activity of quinol esters of p-quinone dioxime after nitrosoarenes addition. The reactional ability of nitrosoarenes is proportional to estimated charge value on the oxygen of the nitroso group, with lgk= 11,3+49,7 qO. Quinol esters of p-quinone dioxime are proposed to create three-dimensional rubber paintings and prints.

Abstract: Elastomer layers offer a wide range of surface functionalization options for fiber-reinforced polymer composites (FRPC), e.g. erosion protection or increased impact resistance. Goal of this study was to investigate if it is possible to prepare a textile-based semi-finished product with elastomeric surface, which can easily be used as outermost layer in different liquid composite molding (LCM) processes. For this purpose, different types of elastomer were pressed and vulcanized onto a biaxial glass fiber fabric. Target of this procedure was to reach partial immersion of the elastomer into the textile with remaining dry textile areas. The dry areas of the textile can later be impregnated with a thermoset resin system. The strategy is to have the transition region between elastomer and thermoset within one textile layer and to give a robust and easy to handle semi-finished-product in order to achieve a maximum bonding strength of the elastomer surface to the final composite part. It could be shown by micrographs and computer tomography that the elastomer only penetrates the textile at its boundary. A remarkable microimpregnation of individual filaments within the rovings does not take place. Concerning the manufacturing, since water evaporates during vulcanization, a sufficient process pressure must be maintained throughout the entire vulcanization process to ensure a pore-free elastomer. Peel-off tests similar to DIN EN 28510-1 on the finished composite showed a failure in the laminate and not in the boundary layer between laminate and elastomer, so that the desired high joint strength could be demonstrated.

Abstract: Fibre-metal-elastomer laminates offer the possibility of using material combinations which often have to deal with premature delamination, for example due to different coefficients of thermal expansion or galvanic corrosion due to different electronegativities. The present study deals with laminates made of layers of CFRP and aluminum, each of which is bonded together by an elastomer layer. The shear-soft elastomer also allows the much stiffer aluminum and CFRP layers to be sheared off against each other under bending stress. This leads to complex deformation behavior. The shear of the elastomer also plays a crucial role in the damping behavior of the laminate. Due to large shear deformations in the elastomer layer, the combination of rigid layers and soft elastomer layers shows very good damping behavior according to the principle of constrained layer damping. Since bending vibrations that occur during normal use usually have only small amplitudes, the deformation behavior is of particular interest in the elastic range. Since this deformation behavior is strongly dependent on the shear modulus of the elastomer used and this in turn is strongly influenced by temperature, the deformation behavior is characterized at different temperatures. Within the scope of this investigation, quasi-static 3-point bending tests are carried out on different laminate lay-ups in the temperature range from -40 °C to +80 °C. The laminates are consolidated by compression molding and contain two different EPDM elastomers in varying layer thicknesses, unidirectional CFRP prepreg in biaxial layer lay-up and aluminum 2024 sheets. The deformation behavior is analyzed by digital image correlation. This is used to measure both the bending line of the overall composite and strains over the layer thickness. In particular, the shear in the elastomer layers is evaluated and set in relation to the bending lines. Finally, the ability of the laminate lay-up to damp bending vibrations is evaluated.

Abstract: The development of frost-resistant elastomeric materials with high performance characteristics remains one of the topical issues. Solving this issue will significantly improve the reliability of machines and mechanisms operating under extremely low temperatures. The influence of multi-walled carbon nanotubes on the performance properties of epichlorohydrin rubber was investigated. This rubber of unique frost resistance has low glass transition temperature (T_g = -60 °C).

Abstract: In this paper, influence of new plasticizers on the mechanical and low-temperature properties of rubbers is studied. The subjects of the research are rubbers based on BNKS-18 butadiene-nitrile rubber and Hydrin T-6000 epichlorohydrin rubber (ECHR). As used plasticizers: DINP (diisononylphthalate), TOTM (trioctyltrimellitate), DOA (dioctyladipate), Alphaplast (complex plasticizer based on esters of organic alcohols and acids). For identification the efficiency, rubbers with the studied plasticizers compared with standard rubber, in which plasticizers have not introduced, as well as with rubber in which a widely used industrial plasticizer DOF (dioktilphthalate) was added. Research of the mechanical properties of rubbers based on BNKS-18 showed that the introduction of plasticizers leads to an increase in elasticity and a slight decrease in the strength of rubbers and on the contrary for rubbers based on ECHR. Low-temperature properties of rubbers with all studied plasticizers have an increased level in comparison with standard rubber. In rubber based on BNKS-18, the highest values of the coefficient of frost resistance at-45°C are observed with the introduction of plasticizers Alphaplast and DOA, an increase in the index compared to standard rubber is more than 50%. The same plasticizers have shown the greatest contribution to the increase in frost resistance of rubbers based on ECHR.

Abstract: This paper aims to investigate the damping properties of plate-like carbonyl iron particle (CIP) magnetorheological elastomer (MRE). The damping properties of MRE is mainly dependent on the strength of magnetic field. Anisotropic MRE was fabricated under various magnetic fields strength (70, 210, 345, and 482 mT) and its damping property prior to frequency-dependent was measured using a rheometer. Firstly, the plate-like CIP was first synthesized from spherical CIP using a ball-milling method. The microstructure of plate-like CIP was observed using low vacuum scanning electron microscope. Subsequently, two types of MREs which are isotropic and anisotropic were fabricated using 70 weight percent (wt.%) of plate-like CIP. The experimental results showed that the anisotropic MRE has lower damping factor than isotropic MRE. Meanwhile, the damping factor increases with the increase of frequency.