Use Of Elastomers Research Articles

Design and molecular dynamics of biocompatible WPU/PVA composite hydrogels with enhanced fatigue resistance: Energy dissipation of intermolecular clusters for elastomers

To engineer a hydrogel elastomer for use as an in vivo tissue replacement, it is imperative to ensure superior fatigue resistance, guaranteeing a prolonged service life. Investigating the molecular mechanisms of strain energy accumulation and transmission, which occur during the compression of elastomeric materials, is instrumental in elucidating the causes of hydrogel material fatigue. Such insights are of immense value for the development of durable artificial tissue replacements, ensuring their longevity and sustained functionality within the human body. We synthesized hydrogel elastomers through polyvinyl alcohol (PVA) and waterborne polyurethane (WPU) with good biocompatibility, and studied their fatigue behavior through molecular dynamics (MD). The results of this analysis demonstrate that the introduction of energy dissipation structures between mechanically supported molecular frameworks can enhance the relaxation efficiency of polymers. This improvement leads to enhanced resistance of hydrogels to compression fatigue. A total of 1,000,000 cycles of compression tests were conducted to verify that WPU/PVA did not exhibit any significant compression fatigue under high stress of 50 % strain. In contrast, PVA hydrogel exhibited obvious fatigue due to the absence of an energy dissipation structure. These results revealed the source of compression fatigue resistance of hydrogel elasticity and provided powerful guidance for the design and synthesis of artificial tissues.

New methods to increasing efficiency for durability design of elastomeric bushings

The use of elastomers in modern road vehicles can solve many design conflicts in the development process. The prerequisite for this is a detailed calculability of the component properties, which are dependent on the geometric shape, the choice of material and the parameters of the manufacturing process. A robust method for calculating parameter-property relationships of elastomer bushings based on physical models and machine learning approaches allows these relationships to be calculated in the early phases of vehicle development. Viscoelastic material properties represent a major challenge for the durability design of elastomer components in load data acquisition. With the help of the modeling approaches developed here for load data analysis, load paths with elastomer bushings in the vehicle can be calculated much more accurately for high loads. A new method for experimental component validation is presented, which reduces the costly testing time for operational load tests by up to 85%. This method uses multi-axis block programs and achieves damage patterns comparable to the operational load test.

Fractography and Tensile studies on the effect of different carbon fillers reinforced hybrid nanocomposites

The use of elastomers has become increasingly important in a variety of industries, including automotive, medical, and food packaging. The adaptability of elastomers to different mechanical stresses has made them a popular choice for these applications. However, the mechanical properties of elastomers can be further enhanced by adding suitable fillers. In this study, the effects of different carbon fillers, namely carbon black, carbon graphite, and carbon nanotubes, on the tensile strength of elastomeric materials were investigated. Different combinations of plain silicone with varying concentrations of CB, CG, and CNT fillers were prepared using a solution casting method. The concentrations of the fillers ranged from 5% to 15% with an interval of 5%. The tensile strength of each combination was measured, and the results showed that the maximum tensile strength was achieved with the combination of CNT at 15% loading. The results of this study highlight the importance of filler selection in enhancing the mechanical properties of elastomers. Carbon fillers, particularly CNTs, have shown to be effective in improving the tensile strength of elastomeric materials. This has important implications for various industries, particularly in the development of new materials for applications in the automotive and medical fields. The use of elastomers in the automotive industry has become increasingly important due to their ability to absorb mechanical shocks and vibrations. Elastomeric materials have also found applications in the medical field, such as in the development of artificial skin, blood pumps, drug delivery systems, and implants. The use of elastomers in food packaging has also become popular due to their ability to provide a barrier against oxygen and moisture. The use of carbon fillers in elastomeric materials has the potential to significantly enhance their mechanical properties, particularly their tensile strength. This study provides valuable insights into the effects of different carbon fillers on the tensile strength of elastomers, which can help in the development of new materials for various industrial applications.

Material Characterization of Elastomeric Bearing Elements in Wave Energy Converters

According to the European Council, 75% of the greenhouse emissions are caused by energy production and use. In order to decarbonize the energy sector, more research is focused towards the renewable energy sources. Among the many available resources, wave energy is one of the key resources to consider. As part of the research, KTH is developing a winch based point absorber wave energy converter. The winch consists of a chain link with elastomer bearings wound around a drum. The winding and unwinding motion of chain converts wave motion into electricity. A typical winch based wave energy converter undergoes around 80 million cycles in its lifetime. This calls for a durable system design requiring minimal service and maintenance. With an elastomer bearing, the winding and unwinding of the chain over the drum is realized as deformation of the elastomer thereby eliminating sliding. While the use of elastomer enables an efficient design, it also makes it more challenging due to its highly non-linear and viscoelastic behavior. A constitutive model is necessary to determine material characteristics of an elastomer for different loading conditions. In this work, a systematic design process is outlined and an attempt is made to determine a suitable hyperelastic material model for the elastomer. The study is focused on two materials – silicone and polyurethane. The test samples are compressed and followed by shear in deformation. For material model determination, the test data is curve fit and later verified using finite element method. The material is assumed incompressible.

Enhancing the interfacial bond strength of aluminum/polymer laminated film of the soft package lithium‐ion battery through polydopamine surface modification

AbstractThe aluminum (Al) foil used in Al/polymer laminated film of the soft package lithium‐ion battery (LIB) is widely treated with a hexavalent chromate conversion coating to increase the adhesive strength and durability of the adhesive joint. Given that hexavalent chromate is toxic and carcinogenic, a novel and chromate‐free method was developed in this study for surface modification of the Al foil using polydopamine (PDA) functionalization after titanium (Ti) chemical conversion. Ti conversion favors the deposition of PDA and introduces more functional groups of PDA on the Al surface. A novel polypropylene‐based hot melt adhesive, MAH‐g‐(PP/PBE), was prepared by melt grafting of maleic anhydride on the blend of polypropylene and propylene‐based elastomer for use as the inner adhesive of Al/polymer laminated film. Then, treated Al foil/MAH‐g‐(PP/PBE) composites were prepared and their interfacial adhesive strengths were investigated. The results show that the amine and catechol groups of PDA improve the interfacial adhesion between adhesive and Al foil by improving the wettability and interfacial interaction. The peel strength between MAH‐g‐(PP/PBE) and PDA functionalized Al foil after Ti conversion treatment can reach 3.55 N/mm, which is increased by 322% compared with that between MAH‐g‐PP and untreated Al foil. PDA functionalization after Ti chemical conversion and MAH‐g‐(PP/PBE) have great potential to improve interfacial adhesion of Al/polymer laminated film used in LIB package.

Study of the influence of rubber on stremgth properties of carbon plastic

The use of elastomers allows us to purposefully change the structure of epoxy compositions, which largely determines the characteristics. Of particular interest are elastomers, such as silicone and polyurethane rubbers. In experimental works for the manufacture of carbon fiber plates, we used the method of manual molding with mechanical pressing. This technology is economical, does not require large labor costs, and less material consumption than when using other methods of formation. The effect of polyurethane and silicone rubbers as modifiers of increasing the impact strength of epoxy resin Etal-Inject-T hot curing has been studied. To determine the compressive strength of carbon fiber, the samples were tested on a universal test machine MUP200. The impact strength of carbon fiber was determined by the Charpy method. It is established that polyurethane and silicone rubbers have the same qualitative effect on the properties of epoxy resins. When modifying carbon fiber with polyurethane rubber with an increase in the content of up to 10%, the impact strength of carbon fiber increases to a maximum of 215 kJ/m2, with a significant increase in compressive strength up to 495 MPa. Optimal results were obtained with polyurethane rubber at 10% content of the substance. The main role of rubber in increasing the strength and elasticity of the material is that when the impact in a small amount of carbon fiber concentrates a lot of mechanical energy, the rubbers are stress concentrators, so the crack arises in the matrix adjacent to the elastomer (rubber). The increase in the toughness of the material can be associated with the formation of a dispersed phase of rubber, which loosens the structure of the cured epoxy resin.

The effectiveness of rubbers based on ethylene propylene rubbers as radiation-resistant materials

The article discusses the main aspects of the use of rubber products based on triple ethylene propylene rubbers of domestic and foreign production, filled with an anti-radiation additive based on a composition of oxides of rare earth elements, as radiation-resistant elastomeric materials. The use of elastomers in the nuclear industry makes it possible to solve many urgent problems and ensure the operation of many critical products and mechanisms, the functioning of which is not possible without the use of elastic materials. This paper presents the results of the study and comparison of the physico-mechanical and operational properties of rubbers based on various ethylene propylene rubbers of domestic and foreign production with the addition of anti-radiation additive VKR-5M for their use as radiation-resistant elastomeric materials. The basic physical, mechanical and operational characteristics of rubber mixtures and rubbers based on ethylene propylene rubbers of domestic and foreign production have been studied. The main mechanisms and properties of radiation aging of elastomers, as well as ways to increase their resistance to ionizing radiation are considered. The paper presents the results of studies of frost resistance, heat resistance, radiation and thermal radiation resistance of rubbers based on ethylene propylene rubbers, which contain an anti-radiation additive based on the composition of rare earth element oxides WRC-5M, the advantages and disadvantages of various brands of domestic and foreign ethylene propylene rubbers in various operating conditions, and conclusions are drawn about the effectiveness of the introduction of anti-radiation additives WRC-5M, which increases the radiation resistance of rubbers. Based on the analysis of the data obtained during the work, the most radiation-resistant elastomeric base for rubbers used in conditions of increased radiation exposure was determined.

Use of elastomers as pressure media for fatigue testing of cold forging tools

Cold forging has high potential as a sustainable production technology. With net-shape production, only the material needed for the produced part is used. By not heating up the workpiece, energy consumption is also low. However, this leads to high forming forces and consequently critical stresses in the tools. An accurate prediction of tool life is therefore necessary; both to find measures for its increase and to plan tool changes with minimal machine downtime. Currently there is little data about the fatigue properties of cold forging tool materials. Existing tests to determine this data strongly simplify the tools’ stress state to a uniaxial load. Therefore, a new fatigue test is presented in this paper, which incorporates the actual load conditions of cyclically swelling inner pressures. For this purpose, a high-strength elastomer is used as pressure medium. Its low compressibility and high elasticity allow for cyclic testing with pressures up to at least 2000 MPa. This load causes wear on the elastomer, as it is pressed into the gap between the punch used to apply the load and the fatigue specimen. Therefore, the gap between punch and fatigue specimen should be as low as possible to ensure stable test conditions. Within the scope of the research, fatigue failure already occurred in one specimen. This shows that the compression of elastomers is able to generate very high loads comparable to the cold forging of steel.

Experimental testing of decoupled masonry infills with steel anchors for out-of-plane support under combined in-plane and out-of-plane seismic loading

Because of simple construction process, high energy efficiency, significant fire resistance and excellent sound isolation, masonry infilled reinforced concrete (RC) frame structures are very popular in most of the countries in the world, as well as in seismic active areas. However, many RC frame structures with masonry infills were seriously damaged during earthquake events, as the traditional infills are generally constructed with direct contact to the RC frame which brings undesirable infill/frame interaction. This interaction leads to the activation of the equivalent diagonal strut in the infill panel, due to the RC frame deformation, and combined with seismically induced loads perpendicular to the infill panel often causes total collapses of the masonry infills and heavy damages to the RC frames. This fact was the motivation for developing different approaches for improving the behaviour of masonry infills, where infill isolation (decoupling) from the frame has been more intensively studied in the last decade. In-plane isolation of the infill wall reduces infill activation, but causes the need for additional measures to restrain out-of-plane movements. This can be provided by installing steel anchors, as proposed by some researchers. Within the framework of European research project INSYSME (Innovative Systems for Earthquake Resistant Masonry Enclosures in Reinforced Concrete Buildings) the system based on a use of elastomers for in-plane decoupling and steel anchors for out-of-plane restrain was tested. This constructive solution was tested and deeply investigated during the experimental campaign where traditional and decoupled masonry infilled RC frames with anchors were subjected to separate and combined in-plane ‬and out-of-plane loading. Based on a detailed evaluation and comparison of the test results, the performance and effectiveness of the developed system are illustrated.

Compression Molding and Nickel Molds for Directional Gecko-Inspired Adhesives

Abstract In the fabrication of directional gecko-inspired adhesives, a new capability made possible by the availability of metal molds is hot compression molding. This molding process allows the use of elastomers with much higher toughness than those cast at ambient temperature and pressure, as has been the common case in fabricating adhesives. In addition, it permits fast cycle times (minutes instead of hours), which is useful for volume manufacturing. We present the results of hot compression molding of elastomers in metal molds created with overhanging and tapered microscopic surface features, which give rise to anisotropic adhesion. We show that the adhesive performance so obtained is equivalent to that obtained earlier with polydimethylsiloxane (PDMS).

Mechanical Properties and Reliability of Parametrically Designed Architected Materials Using Urethane Elastomers.

Achieving multiple physical properties from a single material through three-dimensional (3D) printing is important for manufacturing applications. In addition, industrial-level durability and reliability is necessary for realizing individualized manufacturing of devices using 3D printers. We investigated the properties of architected materials composed of ultraviolet (UV)-cured urethane elastomers for use as insoles. The durability and reliability of microlattice and metafoam architected materials were compared with those composed of various foamed materials currently used in medical insoles. The hardness of the architected materials was able to be continuously adjusted by controlling the design parameters, and the combination of the two materials was effective in controlling rebound resilience. In particular, the features of the architected materials were helpful for customizing the insole properties, such as hardness, propulsive force, and shock absorption, according to the user’s needs. Further, using elastomer as a component led to better results in fatigue testing and UV resistance compared with the plastic foam currently used for medical purposes. Specifically, polyethylene and ethylene vinyl acetate were deformed in the fatigue test, and polyurethane was mechanically deteriorated by UV rays. Therefore, these architected materials are expected to be reliable for long-term use in insoles.

Designing scalable elastomeric anti-fouling coatings: Shear strain dissipation via interfacial cavitation

HypothesisSoft elastomers are promising anti-fouling materials and this has been demonstrated for many small elastomer/foulant interfaces. Toughness should control the adhesive fracture of large interfaces, although this has never been shown for elastomers. We hypothesized that energy-dissipative processes like interfacial cavitation are largely responsible for the absence of toughness-mediated fracture for larger elastomer/foulant interfaces. ExperimentsRigid and transparent model foulants of various length were adhered to elastomers exhibiting three different moduli. The length of the foulant and the height above the interfacial plane of the applied force were systematically varied. A phase diagram was established for designing low-modulus, anti-fouling materials as a function of foulant thickness and length. FindingsA new regime of interfacial detachment was observed, where foulants remained partially attached to the surface and interfacial cavitation initiated from the edge of the detached region. Interfacial cracks were arrested before de-bonding the foulant and the majority of the applied energy was dissipated as cavitation bubbles. Our analysis showed that the use of elastomers as anti-fouling materials is limited for large scale applications. Foulant dimensions constrain the design of anti-fouling elastomeric coatings as an applied shear stress can only be exerted at a height above the interface that is less than the foulant thickness. Design rules are presented for the correct fabrication of elastomers to be used as anti-fouling coatings over large interfacial areas.

Healable, Recyclable, and Mechanically Tough Polyurethane Elastomers with Exceptional Damage Tolerance.

There is a huge requirement of elastomers for use in tires, seals, and shock absorbers every year worldwide. In view of a sustainable society, the next generation of elastomers is expected to combine outstanding healing, recycling, and damage-tolerant capacities with high strength, elasticity, and toughness. However, it remains challenging to fabricate such elastomers because the mechanisms for the properties mentioned above are mutually exclusive. Herein, the fabrication of healable, recyclable, and mechanically tough polyurethane (PU) elastomers with outstanding damage tolerance by coordination of multiblock polymers of poly(dimethylsiloxane) (PDMS)/polycaprolactone (PCL) containing hydrogen and coordination bonding motifs with Zn2+ ions is reported. The organization of bipyridine groups coordinated with Zn2+ ions, carbamate groups cross-linked with hydrogen bonds, and crystallized PCL segments generates phase-separated dynamic hierarchical domains. Serving as rigid nanofillers capable of deformation and disintegration under an external force, the dynamic hierarchical domains can strengthen the elastomers and significantly enhance their toughness and fracture energy. As a result, the elastomers exhibit a tensile strength of ≈52.4MPa, a toughness of ≈363.8MJm-3 , and an exceptional fracture energy of ≈192.9kJm-2 . Furthermore, the elastomers can be conveniently healed and recycled to regain their original mechanical properties and integrity under heating.

Influência da data de validade na estabilidade dimensional dos elastômeros

Os materiais de impressão são utilizados na confecção de modelos em diferentes áreas da odontologia, com ênfase na reabilitação oral com próteses fixas e removíveis ou dentaduras. O objetivo foi comparar a estabilidade dimensional de impressões baseadas em elastômeros de polivinilsiloxano (Express) e poliéter (Impregum Soft) realizadas 2 anos após sua data de validade com impressões que não ultrapassaram esse período. As impressões foram realizadas sobre matriz com moldeira metálica; eles foram removidos após a polimerização e divididos em 4 grupos (n = 5). A estabilidade dimensional foi avaliada por microscopia óptica na linha de 20 µm com comprimento de 25 mm (padrão ISO 4823). Os valores de estabilidade dimensional (%) foram submetidos a ANOVA two-way (material x data de validade) e teste de Tukey (α = 0,05). Com base na análise da data de validade como fator independente (p = 0,017), os valores médios de estabilidade dimensional registrados para a impressão de elastômero 2 anos após a data de expiração (99,89%) foram estatisticamente inferiores aos valores registrados para o não expirado (99,92%) As alterações decorrentes do uso dos elastômeros 2 anos após o seu vencimento não afetam a estabilidade dimensional das próteses decorrentes dessas impressões.

Use Of Elastomers as Sound-Absorbing Materials in Silencers for Ventilation Systems

Use Of Elastomers as Sound-Absorbing Materials in Silencers for Ventilation Systems

Investigation on Synthesis and Application Performance of Elastomers with Biogenic Myrcene

Due to concerns regarding fuel consumption and environmental issues arising from the use of elastomers, particularly in the automobile industry, we investigated the strategy of fabricating elastome...

Pleat Effects With Alternative Materials and Finishing Methods

In this study, various pleating methods formed by shrinking and finishing are experienced as an alternative to the pleats formed with weaving method, numerical and visual values of these methods were determined and in the conclusion part, their contributions to new design ideas were analyzed. In the experimental study, the factors such as weaving method, structure, and density were kept at standard values, besides polyurethane-elastomer, wool and cotton yarns that could shrink under different conditions were used as variable groups. As a result, it was observed that the results obtained from the fabrics passing through alternative processes such as the use of elastomer, fulling, and caustic soda application, supported ‘the local shrinking on fabrics and clothes’ idea.

Advances in Polymeric Materials for Electromechanical Devices.

Electroactive polymers (EAP) provide lightweight and cost-effective materials that enable the next generation of electromechanical devices. Commercial polymers have historically dominated research in EAP devices due to their availability. However, several drawbacks of these materials have limited their commercial applications, necessitating new materials for the commercial success of future EAP devices. This review highlights recent advances in novel EAPs for ionic polymer-metal composites (IPMC) and dielectric elastomer actuators (DEA). Ion-containing block copolymers and charged segmented condensation polymers demonstrate suitable electromechanical properties competitive with Nafion-based IPMCs. In addition, swelling ionic polymer membranes with free ionic liquid enhances ionic conductivity and promotes electromechanical actuation. Synthetic approaches to increasing permittivity in dielectric elastomers are also explored as a method of producing more efficient DEAs. Incorporating polar functional groups into siloxane and acrylic elastomers through grafting or blending provides high-dielectric elastomers for use in DEAs with low driving voltages.

Comparing Physical Human-Robot Interaction with Spring-and Elastomer-Based Series Elastic Actuators.

Physical human-robot interaction (pHRI) is an important consideration in the design of rehabilitation exoskeletons. Series Elastic Actuators (SEAs) are seen as a promising method of introducing compliance and comfort to robotic exoskeletons. Recently, authors have proposed the use of elastomers in SEAs, rather than springs, but there is a dearth of literature comparing how the two compliant elements are perceived by humans. In this paper, we quantitatively and qualitatively compare human interaction with an elastomer and a spring in terms of comfort and motion smoothness, with the aim of informing future SEA design. Two mechanisms were designed to compare human interaction with a spring and elastomer, and a cross-over experimental design was used to help eliminate any learning effects. Overall, the elastomer appeared to be slightly more comfortable and allow slightly smoother motion than the spring, holding promise for the use of elastomers as a means of improving pHRI in exoskeletons actuated by SEAs.

Elastomer Composites with Enhanced Ice Grip Based on Renewable Resources

Slips and falls on icy surfaces can cause serious injuries of people. The primary risk factor for slipping incidents is undoubtedly the decreased friction coefficient between the shoe sole and the ice or snow surface. Nowadays environmental protection has been gaining significance and becoming highly important for the various innovation strategies. In rubber industry the concept of environmental protection is more often associated with the maximum use of elastomers and ingredients from renewable sources in the manufacture of rubber products. The aim of this work is to investigate the possibilities of using elastomers and ingredients from renewable sources—epoxidized natural rubber, silica obtained by rice husks incineration and microcrystalline cellulose—as fillers and rapeseed oil as a process additive in compositions, intended for the manufacture of soles for winter footwear having an increased coefficient of friction to icy surfaces. The tribological tests based on the coefficient of friction evaluated the adhesion of the composites to the icy surfaces at different temperatures. The complex evaluation of developed composites revealed those containing microcrystalline cellulose and biogenic amorphous silica at a 1:1 ratio as the most suitable for making footwear soles because of the best combination of physicо-mechanical properties and coefficient of friction.