Search Results (64)

EPDM (Ethylene Propylene Diene Monomer) rubber is a crucial engineering material, and its mechanical behavior changes with aging duration and ambient temperature. The effects of temperature on the hyperelastic behavior of unaged and aged EPDM rubber are investigated by conducting accelerated aging tests under constant compression and uniaxial compression tests at different temperatures. The experimental results show that prolonged aging induces EPDM rubber to exhibit an approximately linear hardening trend under a constant temperature. For aged EPDM rubber, its stiffness initially decreases and then increases with test temperature. The stress hardening factor was introduced to characterize the influence of the test temperature on the aging effect. The factor exhibits a decreasing trend and then an increasing trend with respect to compression test temperature. The curve of the stress hardening factor versus temperature is approximately a quadratic function. To fit the results, a Neo–Hooke model, a Mooney–Rivlin model, and an improved Mooney–Rivlin model were tested for their fit with the EPDM rubber compression data, covering different experimental conditions. The improved Mooney–Rivlin model had the most consistent results with the experimental data. Based on the experimental results, the parameters of the improved Mooney–Rivlin model were extended to model the effects of temperature and aging time. The proposed constitutive model can effectively describe the hyperelastic behavior of aged EPDM rubber tested at different temperatures. Full article

This study presents an integrated analysis of the dielectric characteristics of nitrile–butadiene rubber (NBR), ethylene–propylene–diene monomer (EPDM), and fluoroelastomer (FKM) polymers. Dispersion spectra were obtained over a wide range of frequencies and temperatures, and, via our self-developed “Dispersion Analysis” program, the obtained dielectric spectra were precisely deconvoluted. Notably, α, α’, β, and γ relaxation phenomena, including the DC conduction process, were identified in NBR, whereas three relaxation processes, namely, α, β, and the Maxwell‒Wagner‒Sillars (MWS) process, as well as DC conduction, were observed in EPDM and FKM copolymers. The activation energies (${\mathrm{E}}_a$) for secondary relaxation—namely, β, γ, and MWS—and the DC conduction process, which are observed in NBR, EPDM, and FKM, were determined via the Arrhenius temperature dependence model, and these values were compared with previously published results. Furthermore, the glass transition temperature (${\mathrm{T}}_g$), extrapolated from the relaxation rate of the α process, was estimated via the Vogel–Fulcher–Tamman–Hesse (VFTH) law. The values of ${\mathrm{T}}_g$ obtained using dielectric spectroscopy for NBR, EPDM, and FKM agreed well with the differential scanning calorimetry (DSC) measurements. This study provides foundational insights into the dielectric properties of widely used rubber polymers, offering a comprehensive reference for future research. Full article

The effect of thermo-oxidative aging on the hyperelastic behavior of ethylene propylene diene monomer (EPDM) rubber was investigated by a combined experimental and theoretical modeling approach. Firstly, the uniaxial tensile test of aged and unaged EPDM rubber was carried out. The test results show that the unaged EPDM rubber had the nonlinear large deformation characteristic of a “S” shape. The stiffness of the EPDM rubber was found to increase with the aging time and aging temperature. Then, in order to quantitatively characterize the hyperelastic behavior of unaged EPDM rubber, the fitting performances of the Mooney–Rivlin, Arruda–Boyce, and Ogden models were compared based on a uniaxial tensile stress–strain curve. The results show that the Ogden model provided a more accurate representation of the hyperelastic behavior of unaged EPDM rubber. Subsequently, the Dakin dynamic equation was adopted to associate the parameters of the Ogden model with the aging time, and the Arrhenius relationship was utilized to introduce the aging temperature into the rate term of the Dakin dynamic equation, thereby establishing an improved Ogden constitutive model. This improved model expanded the Ogden model’s ability to explain aging time and aging temperature. Finally, the improved model prediction results and the test results were compared, and they indicate that the proposed improved Ogden constitutive model can accurately describe the hyperelastic behavior of aged and unaged EPDM rubber. Full article

The damping performance of chlorinated butyl rubber (CIIR) is exceptional; however, its poor processability during vulcanization can lead to numerous defects. Natural rubber (NR) and ethylene propylene diene monomer rubber (EPDM) were selected to blend with CIIR for improving its processing performance. Their effects on the vulcanization characteristics, mechanical properties, and damping performance were investigated. Blending CIIR with NR can considerably increase the vulcanization speed of the rubber compound and improve production efficiency. The tensile strength of the vulcanizate first increases with an increase in the dosage of NR in NR/CIIR, and subsequently, it decreases before increasing again. The tensile strength first increases and then decreases with an increase in the EPDM dosage in EPDM/CIIR vulcanizate. The tensile strength increases by 15.6%when the EPDM dosage is 60 and 80 phr. EPDM and NR have similar effects on the damping performance of CIIR, which were evaluated by fitting the data of loss factor (∆tanδ) versus NR or EPDM dosage. Therefore, the quantity of NR or EPDM can be conveniently calculated based on performance requirements when designing the formula of the CIIR matrix materials. Full article

Integrating rubber with superior low-temperature capabilities, such as ethylene propylene diene monomer (EPDM), is a strategic approach to bolster the low-temperature performance of fluoroelastomer (FKM). However, FKM and EPDM are thermodynamically incompatible. This work synthetized three EPDM-based polar macromolecular compatibilizers, epoxidized EPDM (EPDM-EP), 2,2-trifluoroethylamine-grafted epoxidized EPDM (EPDM-TF), and 2,4-difluorobenzylamine-grafted epoxidized EPDM (EPDM-DF), to enhance the compatibility between FKM and EPDM. These compatibilizers were subsequently incorporated into FKM/EPDM rubber blends. The results revealed that the glass transition temperature (T_g) of FKM/EPDM decreased by 1.3 °C, 2.68 °C, and 2.78 °C, respectively, upon the addition of 10 phr of EPDM-EP, EPDM-TF, or EPDM-DF. Moreover, the T_g of the two phases converged. The tensile strength, elongation at break, and tear strength of the FKM/EPDM rubber blends were also enhanced by the inclusion of these compatibilizers. Notably, EPDM-TF and EPDM-DF exhibited remarkable compatibilization effects due to an increase in polarity. This research not only sheds light on the potential for developing new compatibilizers but also paves the way for innovative applications of FKM and its derivatives. Full article

This study comprehensively investigates the stress distribution and aging effects in Ethylene Propylene Diene Monomer (EPDM) and Liquid Silicone Rubber (LSR) gasket materials through a novel integration of hyperelastic modeling and advanced machine learning techniques. By employing the Mooney–Rivlin, Ogden, and Yeoh hyperelastic models, we evaluated the mechanical behavior of EPDM and LSR under conditions of no aging, heat aging, and combined heat- and sulfuric-acid exposure. Each model revealed distinct sensitivities to stress distribution and material deformation, with peak von Mises stress values indicating that LSR experiences higher internal stress than EPDM across all conditions. For instance, without aging, LSR shows a von Mises stress of 24.17 MPa compared to 14.96 MPa for EPDM, while under heat and sulfuric acid exposure, LSR still exhibits higher stress values, showcasing its resilience under extreme conditions. Additionally, the ensemble learning approach achieved a classification accuracy of 98% for LSR and 84% for EPDM in predicting aging effects, underscoring the robustness of our predictive framework. These findings offer practical implications for selecting suitable gasket materials and developing predictive maintenance strategies in industrial applications, such as fuel cells, where material integrity under stress and aging is paramount. Full article

Ethylene-propylene-diene monomer (EPDM) is a key engineering material; its mechanical characterization is important for the safe use of the material. In this paper, the coupled effects of thermal degradation temperature and time on the tensile mechanical behavior of EPDM rubber were investigated. The tensile stress-strain curves of the aged and unaged EPDM rubber show strong nonlinearity, demonstrating especially rapid stiffening as the strain increases under small deformation. The popular Mooney–Rivlin and Ogden (N = 3) models were chosen to fit the test data, and the results indicate that neither of the classical models can accurately describe the tensile mechanical behavior of this rubber. Six hyperelastic constitutive models, which are excellent for rubber with highly nonlinearity, were employed, and their abilities to reproduce the stress-strain curve of the unaged EPDM were assessed. Finally, the Davis–De–Thomas model was found to be an appropriate hyperelastic model for EPDM rubber. A Dakin-type kinetic relationship was employed to describe the relationships between the model parameters and aging temperature and time, and, combined with the Arrhenius law, a thermal aging constitutive model for EPDM rubber was established. The ability of the proposed model was checked by independent testing data. In the moderate strain range of 200%, the errors remained below 10%. The maximum errors of the prediction results at 85 °C for 4 days and 100 °C for 2 and 4 days were computed to be 17.06%, 17.51% and 19.77%, respectively. This work develops a theoretical approach to predicting the mechanical behavior of rubber material that has suffered thermal aging; this approach is helpful in determining the safe long-term use of the material. Full article

Considering the dilemma of obtaining economic and high-performance composites based on non-polar and main-chain-saturated ethylene propylene diene monomer rubber (EPDM), we proposed an effective and universal filler modification and nanocomposite preparation method. Specifically, the montmorillonite (MMT) surface was coated with polydopamine (PDA) to obtain DMMT, which was confirmed by XRD, XPS, FTIR, and TGA. After compounding DMMT gel with the solid EPDM via the gel compounding method, a silane coupling agent, vinyltrimethoxysilane, was introduced to construct covalent interactions between rubber and filler. Compared with the unmodified MMT filler EPDM, the EPDM/DMMT nanocomposite showed much fewer filler aggregates in the matrix. The highest tensile strength of the composites reached 6.5 MPa with 10 phr DMMT, almost 200% higher than that of pure EPDM. Full article

The burning of Ethylene–Propylene–Diene Monomer (EPDM) rubber generates substantial smoke, posing a severe threat to the environment and personal safety. Considering the growing emphasis on safety and environmental protection, conventional non-smoke-suppressing flame retardants no longer satisfy the present application requirements. Consequently, there is an urgent need to develop a novel flame retardant capable of suppressing smoke formation while providing flame retardancy. Sepiolite (SEP), a porous silicate clay mineral abundant in silica and magnesium, exhibits notable advantages in the realm of flame retardancy and smoke suppression. This research focuses on the synthesis of two highly efficient flame-retardant smoke suppression systems, namely AEGS and PEGS, using Enteromorpha (EN), graphene (GE), sepiolite (SEP), ammonium polyphosphate (APP), and/or piperazine pyrophosphate (PPAP). The studied flame-retardant systems were then applied to EPDM rubber and the flame-retardant and smoke suppression abilities of EPDM/AEGS and EPDM/PEGS composites were compared. The findings indicate that the porous structure of sepiolite plays a significant role in reducing smoke emissions for EPDM composites during combustion. Full article

The automotive industry is entering a digital revolution, driven by the need to develop new products in less time that are high-quality and environmentally friendly. A proper manufacturing process influences the performance of the door grommet during its lifetime. In this work, uniaxial tensile tests based on molecular dynamics simulations have been performed on an ethylene–propylene–diene monomer (EPDM) material to investigate the effect of the crosslink density and its variation with temperature. The Mooney–Rivlin (MR) model is used to fit the results of molecular dynamics (MD) simulations in this paper and an exponential-type model is proposed to calculate the parameters $C_1\left(T\right)$ and $C_2\left(T\right)$. The experimental results, confirmed by hardness tests of the cured part according to ASTM 1415-88, show that the free volume fraction and the crosslink density have a significant effect on the stiffness of the EPDM material in a deformed state. The results of molecular dynamics superposition on the MR model agree reasonably well with the macroscopically observed mechanical behavior and tensile stress of the EPDM at the molecular level. This work allows the accurate characterization of the stress–strain behavior of rubber-like materials subjected to deformation and can provide valuable information for their widespread application in the injection molding industry. Full article

Safety and reliability are the major challenges to face for the development and acceptance of hydrogen technology. It is therefore crucial to deeply study material compatibility, in particular for tribological components that are directly in contact with hydrogen. Some of the most critical parts are sealing materials that need increased safety requirements. In this study, the fretting behavior of several elastomer materials were evaluated against 316L stainless steel in an air and hydrogen environment up to 10 MPa. Several grades of cross-linked hydrogenated acrylonitrile butadiene (HNBR), acrylonitrile butadiene (NBR) and ethylene propylene diene monomer rubbers (EPDM) were investigated. Furthermore, aging experiments were conducted for 7 days under static conditions in 100 MPa of hydrogen followed by rapid gas decompression. Fretting tests revealed that the wear of these compounds is significantly affected by the hydrogen environment compared to air, especially with NBR grades. After the aging experiment, the friction response of the HNBR grades is characterized by increased adhesion due to elastic deformation, leading to partial slip. Full article

Ethylene propylene diene monomer (EPDM) is a synthetic rubber widely used in industry and commerce due to its high thermal and chemical resistance. Nanotechnology has enabled the incorporation of nanomaterials into polymeric matrixes that maintain their flexibility and conformation, allowing them to achieve properties previously unattainable, such as improved tensile and chemical resistance. In this work, we summarize the influence of different nanostructures on the mechanical, thermal, and electrical properties of EPDM-based materials to keep up with current research and support future research into synthetic rubber nanocomposites. Full article

One of the environmental problems worldwide is the enormous number of surgical masks used during the COVID-19 pandemic due to the measures imposed by the World Health Organization on the mandatory use of masks in public spaces. The current study is a potential circular economy approach to recycling the surgical masks discarded into the environment during the COVID-19 pandemic for use in bituminous asphalt pavement. FTIR analysis showed that the surgical masks used were made from ethylene propylene diene monomer (EPDM) rubber modified with polypropylene. The effects of the addition of surgical masks in bituminous asphalt on the performance of the base course were demonstrated in this study. The morphology and elemental composition of the bituminous asphalt pavement samples with two ratios of surgical mask composition were investigated by SEM-EDX and the performance of the modified bituminous asphalt pavement was determined by Marshall stability, flow rate, solid–liquid ratio, apparent density, and water absorption. The study refers to the technological innovation of using surgical masks in the formulation of AB 31.5 bituminous asphalt base course, which brings tremendous benefits to the environment by reducing the damage caused by the COVID-19 pandemic. Full article

An experimental device fixed with a laser displacement sensor was assembled to investigate the rebound behaviors and damping mechanism of rubber balls prepared with ethylene-propylene-diene monomer (EPDM)/chlorinated butyl rubber (CIIR) blends. The result showed that a prediction model was proposed to characterize the damping capacity by using the rebound height of the rubber balls. The lower rebound height corresponded to better damping capacity. A modified equation relating to the rebound height has been obtained from the theoretical derivation on the basis of the dynamic mechanical analysis, showing that the rebound height was affected by the deformation frequency, the external excitation, and the nature of rubber blends. Furthermore, the energy dissipation rate (EDR), defined by the ratio of the height loss to the rebound time, was proposed to further characterize the damping capacity. The EDR value was shown to be highest for the pure CIIR and lowest for the pure EPDM, exhibiting a decreasing trend with the increase in EPDM content in the rubber blends. It can be expected that the damping capacity of the EPDM/CIIR blends decreases with the decrease in external excitation, the conclusion of which plays a key role in the formulation design of viscoelastic damping rubber materials. Full article

The aging behavior and life prediction of rubber composites are crucial for ensuring high-voltage transmission line safety. In this study, commercially available ethylene–propylene–diene monomer (EPDM) spacer composites were chosen and investigated to elucidate the structure and performance changes under various aging conditions. The results showed an increased C=O peak intensity with increasing aging time, suggesting intensified oxidation of ethylene and propylene units. Furthermore, the surface morphology of commercial EPDM composites displayed increased roughness and aggregation after aging. Furthermore, hardness, modulus at 100% elongation, and tensile strength of commercial EPDM composites exhibited a general increase, while elongation at break decreased. Additionally, the damping performance decreased significantly after aging, with a 20.6% reduction in loss factor (20 °C) after aging at 100 °C for 672 h. With increasing aging time and temperature, the compression set gradually rose due to the irreversible movement of the rubber chains under stress. A life prediction model was developed based on a compression set to estimate the lifetime of rubber composites for spacer bars. The results showed that the product’s life was 8.4 years at 20 °C. Therefore, the establishment of a life prediction model for rubber composites can provide valuable technical support for spacer product services. Full article