Types Of Elastomers Research Articles

Importance of Mullins effect in commercial silicone elastomer formulations for soft robotics

AbstractSilicone elastomers are used in a wide range of applications, including artificial muscles, biomedical devices, and soft robotics, for which chemical, thermal, and mechanical stability are important requirements that these elastomers must fulfill. However, to ensure that silicone elastomers' properties and performance remain constant under long‐term deployment, it is necessary to examine and account for the Mullins effect, which has the potential to significantly alter certain elastomer properties of interest. In this article, the mechanical properties of soft and hard commercial silicone elastomers and two blends of commercial silicone elastomers are investigated—specifically their softening behavior due to the Mullins effect. Ultimate stresses, ultimate strains, and Young's moduli are obtained from uniaxial tensile tests. Results show that the point of softening greatly depends on both the elastomer type and its strain history. Furthermore, a significant permanent set is observed in the softest commercial formulations.

Research of resistance to water-jet wear of plastic and steel pipes. Assessment of the main parameters that affect the wear rate of hydraulic transport systems

It has been found that the use of certain types of thermoplastic elastomers as a co-extruded coating of the inner surface of plastic pipe systems can significantly increase the lifetime of pipeline hydrotransport when exposed to hydraulic mixtures, in particular tailings of iron ore processing. The comparison of polyethylene and steel pipes resistance to water-jet wear is made. The influence of the concentration, dispersion, and speed of hydraulic mixtures on the wear rate is estimated.

Analysis of the Effect of Shape Factor on Cork–Rubber Composites under Small Strain Compression

Like other types of elastomers, different geometries of the same cork–rubber material present different mechanical behaviour when subject to compression between bonded plates. To validate the application of Hooke’s Law on cork–rubber materials, under compression at small strains, a set of experimental and numerical analyses has been conducted. Using finite element analysis, a methodology is described to relate frictionless and frictional compression between a cork–rubber sample and loading plates. Based on that, the performance of square cross-section blocks with other dimensions can be evaluated. The results obtained by this approach showed a good agreement with experimental compression tests and with outputs from other models available in the literature relating Young and apparent compression moduli.

Recovery from fatigue of pneumatic artificial muscle using a thermoplastic elastomer

Robots, driven by soft actuators, aim at ensuring human safety. Owing to their relatively higher output force than other soft actuators, rubber pneumatic artificial muscles (PAM) are actively researched. In particular, straight-fiber pneumatic artificial muscle (SFPAM) has high output and contraction abilities. However, significant deformation places substantial strain on rubber, shortening the lifespan of artificial muscle. Therefore, improving the lifespan of artificial muscle is important for practical applications. To achieve this, this study proposes the use of a repairable elastomer with artificial muscle. We suggest that the lifespan of artificial muscle can be improved using a maintenance process. Herein, styrene-ethylene-propylene-styrene (SEPS), a type of thermoplastic elastomer, was selected and a heat-based maintenance method proposed. Fatigue test results using the SEPS sample showed an increase in fatigue lifespan using the proposed heat treatment. However, we also have to address undesired deformation of SEPS exhibiting plastic property by heating. To avoid contact with SEPS during heating, we proposed contactless heating method with microwave. To make SEPS catch microwave, we created carbon black-blended SEPS samples. Fatigue tests indicated that the heat treatment method with microwave also increased the lifespan of carbon black-blended SEPS samples.

Valorization of waste polyethylene by blending with ethylene‐vinylacetate and incorporating a new type of compatibilizer

AbstractNowadays polyethylene is one of the polymers produced in the greatest volume and the amount of generated waste high‐density polyethylene (w‐HDPE) is significant as well. Valorization and recycling of w‐HDPE can be realized by blending with different types of polymers and/or elastomers for example, ethylene‐vinyl acetate (EVA). For the purpose of boosting of interfacial interactions between these two polymers experimental olefin‐maleic‐anhydride based additives have been incorporated into the blends after optimization of the processing temperature. Impact and tensile tests have been carried out in our research work besides microscopy measurements and investigation of the effects of additive structure by FT‐IR and rheology. At higher processing temperature (220°C) both tensile properties and Charpy impact strength were increased, latter one improved by 245% measured at 5°C while elongation at break enhanced by 182% with incorporation of some experimental additives compared to the neat 70/30 w‐HDPE/EVA. Changes in the hydrocarbon molecular chains of experimentally compatibilized blends were observed based on FT‐IR results and rheological measurements. It can be concluded that one of the most basic notions of sustainability, the 4R's (reduce, recycle, reuse, recover) has been satisfied in a successful way.

Efficiency of polyurethane elastomer containing sulfonated groups as chain extender in removing Malachite green

A novel type of polyurethane elastomer (PUE) containing nanocomposites of sodium alginate thiacalix[4]arene macrocycles including sodium alginate-thiacalix[4]arene and sodium alginate-tetra-sulfonated thaiacalix[4]arene (SA-TSTCA) was prepared. The key role of these nanocomposites merged into polyurethane elastomers is to function as chain extenders. To provide profound insight into the structural, thermal, mechanical, morphological and hydrophilic properties of the samples, several techniques were employed, namely Fourier transform infrared spectroscopy, thermal gravimetric analysis, scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). Also the results were compared with the results of polyurethane elastomer based on glycerol (Gly) as chain extender. The results showed that the samples extended with nanocomposites as chain extender have better thermal and mechanical properties and between them the PUE containing SA-TSTCA showed higher thermal and mechanical properties. Furthermore, these elastomers have been used as adsorbent for removal of Malachite green (MG) for investigation of the effect of sulfonated groups introduced on the chain extender. The results revealed that SA-TSTCA-based polyurethane elastomer nanocomposite could well adsorb Malachite green from aqueous media by a batch adsorption method. The pseudo-first-order and pseudo-second-order kinetic models were employed to provide an in-depth study of the adsorption capacity of MG, suggesting that its adsorption onto PUE/SA-TSTCA elastomer was in accordance with pseudo-second-order kinetic process. A possible mechanism of adsorption was suggested where π–π stacking interactions, H-bonding interaction and electrostatic attraction controlled the MG adsorption.

Dimethyl Ether (DME) and DME/LPG mixtures resistance characteristics of modified natural rubber compounds

The use of Liquified Petroleum Gas (LPG) in Indonesia is quite high, the volume reaches 6.7 million tons per year. Indonesia currently still imports 70% of its domestic consumption of LPG, or about IDR 40 trillion. Imports of Liquid Petroleum Gas (LPG) continues to increase every year. Dimethyl ether (DME) is one alternative to renewable fuels because its availability in the country is quite abundant. When DME applied as household fuels, some components such as metals and rubber should include resistance to DME, such as stoves, rubber hoses, rubber components in regulators and tube valves. Lemigas has succeeded in developing a DME resistant stove but still not found a rubber that is resistant to DME. This research aims to find a natural rubber formula that is resistant to DME and DME / LPG mixture. The study was conducted by varying the dose of sulphur (0.5, 1.5, and 3.5 phr) using 2 types of elastomer, Natural Rubber (NR) and Nitrile Butadiene Rubber (NBR). Immersion was carried out in DME and 3 variations of the DME/LPG mixture (10/90, 20/80, 30/70). The results showed that the compound formula using natural rubber with a sulphur dose of 1.5 phr has the best resistance to DME and DME/LPG mixtures.

Effect of Addition of Carbon Nanotubes on Electrical Conductance and Heat Dissipation of Elastomers at Flow of Direct Current

The heat effects at flow of direct current in nanomodified elastomers of two types (polyurethane and silicone compounds) were investigated. The multiwalled carbon nanotubes (MWCNT) synthesized over the (Co–Mo)/(Al2O3–MgO) and (Fe–Co)/2.1Al2O3 catalysts were used for nanomodification. The particle size analysis of MWCNT was carried out because the MWCNTs with various morphological parameters were synthesized over this type of catalysts. The composite manufactured on the basis of a silicone compound modified by 7 wt % of MWCNTs synthesized over the (Co–Mo)/(Al2O3–MgO) catalyst has the highest electrical conductivity (1.66 × 10–1 S cm–1), and the composite manufactured from the polyurethane compound modified by 1 wt % of MWCNT synthesized over the (Fe–Co)/2.1Al2O3 catalyst has the lowest electrical conductivity (6 × 10–10 S cm–1). Variations in heat dissipations for various types of elastomers modified by MWCNT were detected by using the noncontact method of measuring of temperature field on the surface of samples. The manner of stabilized heat dissipation which is natural for the materials with a positive temperature coefficient of resistance was found. The highest intensity of heat dissipations combined with uniform distribution of the temperature field was observed for the samples manufactured on the basis of a silicone compound containing 7 wt % of the MWCNTs synthesized over the (Fe–Co)/2.1Al2O3 catalyst. The maximum heating temperature for the sample operating under the voltage of 6 V of direct current was 102°C. Nonuniformity of heat dissipations is specific to almost all samples manufactured on the basis of the polyurethane compound. In this case, the samples based on the silicone compound demonstrate uniform heating at any level of filling by the MWCNTs. As a part of the study, a honey-combed sample was obtained, which, under the voltage of 6 V of direct current, was heated to 100°C and had a uniform distribution of the temperature field.

A type of self-healable, dissoluble and stretchable organosilicon elastomer for flexible electronic devices

Polymer materials with good mechanical properties, solubility and flexible self-healing conditions were of great value to the development of modern high-tech fields. Herein, α,ω-aminopropyl terminated polydimethylsiloxane (PDMS, Mn = 2000), terephthalaldehyd (TA) and 3-aminophenylboronic acid (APB) were used to construct a three-dimensional network via simple and effective reactions, such as the Schiff base reaction and the dehydration reaction. The obtained PDMS elastomer prepared by low molecular weight main chain could achieve very good mechanical performance of tensile strength 2.54 MPa and the average elongation at break of 275.3%. Through the dynamic imine bonds formed by Schiff base reaction and the coordination of boron oxygen bonds and hydrogen bonds, we have constructed a high efficiency self-healing network. The network could achieve self-healing at room temperature with a self-healing efficiency of 91.6%, at high temperature with a self-healing efficiency of 95.1% and in water at a self-healing efficiency of 85.5%. In addition, multi-walled carbon nanotubes (MWCNTs) was compounded with a polymer system to prepare self-healing flexible electronic devices. Due to the electric resistance of PDMS/MWCNTs sensitively modified with the change of tensile and bending angles, this might be of great significance for the application of sensors.

Optimisation of Compression Moulding Parameter for NR/EPDM Material

Natural Rubber/Ethylene Propylene Diene Monomer (NR/EPDM) elastomeric has gaining popularity in the automotive industry owing to the fact in term of sustainability. With extensive studies and an increasing number of applications for future advancement, the need for an accurate and reliable guide in processing this type of elastomer has increased enormously. The present work deals with the study of compression moulding parameters (i.e. temperature, pressure, heating time and pressure time) and its effects against NR/EPDM elastomeric mechanical properties (i.e. ultimate tensile strength (UTS), cross-link density and eccentricity error) aim on establishing optimized processing parameters setup. The optimizations are achieved through the Response Surface Methodology (RSM) and mathematical model for each response is developed to access the relationship between the parameters. Adequacy of models is analysed statistically using analysis of variance (ANOVA) in the determination of significant input variables and possible interactions. Lastly, multi objectives optimization is performed through numerical optimization and predicted results are validated. Strong agreement between experimental and the selected solution are found in between 93% and 96%, thus validating the solution as an optimal run condition. The findings suggest that temperature and heating time is the main factor affecting ultimate tensile strength, whereas for cross-link density there is only one significant parameter which is temperature. UTS and cross-link density decrease with the increases of the temperature and heating time due to the degradation (temperature too high for NR/EPDM working temperature). Therefore, it is recommended to start the process below the NR/EPDM degradation point to avoid the scissoring rubber take place and subsequently improving the mechanical properties

A flexible self-arched biosensor based on combination of piezoelectric and triboelectric effects

Wearable electronics bring convenience to our lives. Among them, flexible physiological sensors such as pulse sensors that can be used to monitor human health play critical roles. Recently, pulse sensors based on nanogenerators have received extensive attention in recent years, which have considerable properties including high sensitivity, signal-to-noise ratio and low power consumption due to their self-powered mode. Here, a self-powered pulse sensor based on a self-arched nanogenerator (SANG) with a combined effect of piezoelectric and triboelectric is demonstrated for real-time monitoring pulse waveform of the radial artery. The output properties of SANG are related to the morphology of the self-arched structure, which can be easily regulated by adjusting the mass ratio of two types of silicone elastomers of PDMS and Ecoflex. It is a convenient approach compared to conventional ones that should make a different special mold to obtain arched structures. For pulse sensing, the sensitivity and the stability of the SANG are qualified due to its unique self-arched structure and hybrid effect of triboelectric and piezoelectric for converting tiny mechanical signals into electric ones effectively.

Characterization and Properties of Polyurea Elastomer Used as Blast Mitigation Agent

The blast that caused from terrorist activities, explosion and weapons effect on not only the human life, but also the architectural structure. The development of materials used to protect them is needed. Polyurea is a one type of elastomer that derive from the reaction product of an isocyanate component and a synthetic resin blend component through step-growth polymerization. It is revealed that polyurea is a new entrant in the field of elastomer has received enormous attention in view of its excellent blast mitigation properties and ballistic protection. In this work, the microstructure and elemental composition of polyurea samples are studied using scanning electron microscope coupled with energy dispersive X-ray spectrometer (SEM-EDS). The main composition consisted of carbon, oxygen and silica approximately 63-75, 17-29, and 0.15-1.69 wt%, respectively. Sulfur and chlorine present as the chain extender. Titanium is added to modify its structure. Other elements present as the additives, fillers and pigments. Atomic force microscopy (AFM) is conducted to confirm nano-scale composition. Dynamic mechanical, thermal and tensile properties are also studied. It is shown that the modulus and loss factor increase as the increasing of the frequency and temperature. The elongation capacity is greater than 100%. Infrared spectroscopy based on synchrotron radiation (SR IR) shows the various constituents of the composition in the form of the functional groups along with the wave number.

A novel type of self-healing silicone elastomers with reversible cross-linked network based on the disulfide, hydrogen and metal-ligand bonds

Herein, we report an innovative cross-linked network of silicone elastomer with good stretchability, thermal stability and autonomous self-healing. This type of elastomers was easily prepared by aminopropyl terminated polydimethylsiloxane (A-PDMS), thioctic acid (TA) and 2,6-pyridine dialdehyde (Py). As we know, TA was firstly incorporated into the reversible network of silicones to supply the dynamic disulfide bonds and endow the self-healing properties. Py was also introduced into the network which acted as the metal-ligand binding sites. Consequently, silicone elastomers with three different types of chemical interactions including the disulfide bonds, hydrogen bonds and metal-ligand bonds were obtained. Especially, they possessed good anticorrosion and strong adhesion affinity. We expected this type of silicone elastomers could be applied into the soft robotics, wearable electronics and stretchable circuit constructed.

Anisotropic swelling of elastomers filled with aligned 2D materials

A comprehensive study has been undertaken on the dimensional swelling of graphene-reinforced elastomers in liquids. Anisotropic swelling was observed for samples reinforced with graphene nanoplatelets (GNPs), induced by the in-plane orientation of the GNPs. Upon the addition of the GNPs, the diameter swelling ratio of the nanocomposites was significantly reduced, whereas the thickness swelling ratio increased and was even greater than that of the unfilled elastomers. The swelling phenomenon has been analyzed in terms of a modification of the Flory–Rehner theory. The newly-derived equations proposed herein, can accurately predict the dependence of dimensional swelling (diameter and thickness) on volume swelling, independent of the type of elastomer and solvent. The anisotropic swelling of the samples was also studied in combination with the evaluation of the tensile properties of the filled elastomers. A novel theory that enables the assessment of volume swelling for GNP-reinforced elastomers, based on the filler geometry and volume fraction has been developed. It was found that the swelling of rubber nanocomposites induces a biaxial constraint from the graphene flakes.

Finite Element Modeling and Critical Plane Analysis of a Cut-and-Chip Experiment for Rubber

ABSTRACT Rubber surfaces exposed to concentrated, sliding impacts carry large normal and shearing stresses that can cause damage and the eventual removal of material from the surface. Understanding this cut-and-chip (CC) effect in rubber is key to developing improved tread compounds for tires used in off-road or poor road conditions. To better understand the mechanics involved in the CC process, an analysis was performed of an experiment conducted on a recently introduced device, the Instrumented Chip and Cut Analyzer (ICCA), which repetitively impacts a rigid indenter against a rotating solid rubber wheel. The impact process is carefully controlled and measured on this lab instrument, so that the contact time, normal force, and shear force are all known. The numerical evaluation includes Abaqus finite element analysis (FEA) to determine the stress and strain fields during impact. The FEA results are combined with rubber fracture mechanics characteristics of the material as inputs to the Endurica CL elastomer fatigue solver, which employs critical plane analysis to determine the fatigue response of the specimen surface. The modeling inputs are experimentally determined hyperelastic stress-strain parameters, crack growth rate laws, and crack precursor sizes for carbon black–filled compounds wherein the type of elastomer is varied in order to compare natural rubber (NR), butadiene rubber (BR), and styrene-butadiene rubber (SBR). At the lower impact force, the simulation results were consistent with the relative CC resistances of NR, BR, and SBR measured using the ICCA, which followed the order BR > NR > SBR. Impact-induced temperature increases need to be considered in the fatigue analysis of the higher impact force to provide lifetime predictions that match the experimental CC resistance ranking of NR > SBR > BR.

Caryophyllene as a Precursor of Cross-Linked Materials

This paper aims at the synthesis of a new type of elastomer from caryophyllene. The adopted strategy was to cross-link the polycaryophyllene, which was synthesized by ring-opening metathesis polyme...

Synthesis and Characterization of Linear Polyisoprene Supramolecular Elastomers Based on Quadruple Hydrogen Bonding.

Supramolecular elastomers based on quaternary hydrogen bonding of ureido-pyrimidinone (UPy) groups own special properties such as reversibility, self-healing, and good processability, which can be used in many special fields. In this paper, a novel type of linear polyisoprene supramolecular elastomer (LPSE) was prepared via anionic polymerization by deliberately introducing hydroxyl, isocyanate, and UPy groups into the ends. The formation of supramolecular structure showed significant effects on the microphase structures of LPSE, which was characterized by Fourier-transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), hydrogen nuclear magnetic resonance (1H-NMR), and dynamic mechanical analysis (DMA). Results showed that the introduction of UPy groups played a certain role in the improvement of the thermal stability, toughness, and tensile strength of the elastomer. Moreover, from self-healing tests, the hydrogen bonds of UPy showed dynamic characteristics which were different from covalent sacrificial bonds and exhibited the reassociation phenomenon. This study can not only extend our understanding of the toughening effect of strong hydrogen bonds, but also help us to rationally design new and tough elastomers.

Impact of a mixture of nanofiller and intrinsic pigment on tear strength and hardness of two types of maxillofacial silicone elastomers

The ideal maxillofacial prosthesis should have fine and thin boundaries that bind with the surrounding facial structures and possess high tear strength. This study aims to determine the best percentages of nanofiller (TiO2) and intrinsic pigment (silicone functional intrinsic) that could be mixed in as additives to improve the tear strength of Cosmesil M511 and VST50F silicone elastomers with the least effect on their hardness. In this in vitro experimental study, a total of 80 samples, 40 for each elastomer, were fabricated. Each elastomer sample was split into two equal groups to test for tear strength and Shore A hardness. Each group consisted of 20 samples, including 10 control samples without additives and 10 experimental samples with additives (mixtures of 0.2 wt% nano-TiO2+ 0.25 wt% intrinsic pigment and 0.25 wt% nano-TiO2+ 0.25 wt% intrinsic pigment for the Cosmesil M511 and VST50F silicone elastomers, respectively). Two-way ANOVA and Tukey test were used for comparison; P < 0.05 was considered statistically significant. Significant differences in tear strength were found among all tested groups (P < 0.05). The tear strength of the experimental subgroups significantly increased compared with the control subgroups (P < 0.05). Significant differences in Shore A hardness were also observed among all tested groups (P < 0.05) except between the experimental subgroups of both materials, where a nonsignificant difference was obtained (P > 0.05). Incorporation of select percentages of TiO2 nanofiller and intrinsic pigment into Cosmesil M511 and VST50F silicone elastomers yields improvements in tear strength with a slight increase in hardness.

Comprehensive review of parameters influencing the performance of magnetorheological elastomers embedded in beams

An extensive study was done to find out the different factors which affected the performance of a sandwich beam with a magnetorheological elastomer embedded to its core. The different types of MR elastomers, modes of application of magnetic field, the different boundary conditions and the various FEM studies based upon MR is presented here. A major part of the literature studied indicated that anisotropic MREs exhibited a larger value of MR effect as compared to isotropic MREs but some studies found that isotropic MREs produced a larger MR effect. The effects of localised and homogeneous magnetic field on MRE embedded beams were studied and compared. Three different boundary conditions were considered which are as follows: simply supported, clamped-clamped and cantilever type.

Transparent conductive elastomers with excellent autonomous self-healing capability in harsh organic solvent environments

A new type of transparent conductive elastomer with excellent autonomous self-healing capability in harsh organic solvent environments is reported.