EPDM Research Articles

Reversible Giant Barocaloric Effect with Broad Working Temperature Range in an Amorphous Ethylene Propylene Diene Monomer.

The barocaloric effect of a solid material is an intense research topic due to its potential application in solid-state refrigeration. Among the proposed candidates, elastic polymers are distinctive because their barocaloric responses are independent from a pressure-induced phase transition which makes it possible to realize a broad working temperature range in principle. However, the barocaloric performance of most elastic polymers diminishes significantly as temperature decreases. In this work, giant and reversible barocaloric effects were observed in a broad working temperature range from 252 to 345 K in an amorphous polymer of ethylene propylene diene monomer, which are much higher than the investigated crystalline and partially crystallized ones. It is demonstrated that the degree of crystallinity can be a key factor responsible for the mobility of polymer chains and the corresponding barocaloric performance at low temperatures. The reversible giant barocaloric effects, broad working temperature regions, low cost, and absence of pressure-transmitting fluid make the ethylene propylene diene monomer attractive for solid-state barocaloric refrigeration.

Constituent compatibility and physical properties of bio‐based EUG/EPDM blends

AbstractEucommia ulmoides gum (EUG)/ethylene propylene diene monomer (EPDM) blends were prepared using EUG with high and low molecular weight, respectively, and their physical properties and constituents compatibility were investigated. The blend exhibited superior physical properties and constituents compatibility when EUG with high molecular weight occupied 10 wt%. When its content increased further, the physical properties deteriorated gradually，the results of SEM, DSC, and DMA diagrams indicated poorer constituents compatibility. The blends prepared from EUG with low molecular weight can achieve better compatibility in a comprehensive range of blending ratio. When the EUG content was 20 wt%, the maximum tensile strength of the blend was observed, which was 49.9% higher than that of pure EPDM, its rebound resilience ascended by 5%, and the wear resistance remained nearly unchanged.

Constitutive Model for Thermal-Oxygen-Aged EPDM Rubber Based on the Arrhenius Law.

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.

Structural analysis and sealing capacity of gasketed plate heat exchangers with HNBR and EPDM rubbers

Structural analysis and sealing capacity of gasketed plate heat exchangers with HNBR and EPDM rubbers

Lifetime prediction of EPDM sealing materials with thermal aging under constant compression

Abstract EPDM (Ethylene Propylene Diene Monomer) is an important engineering sealing material. Thermal aging leads to a decline in its service life. In this study, the static sealing lifetime of EPDM sealing materials is investigated by thermal aging experiments under constant compression. Based on the variation pattern of compression set over aging time at different aging temperatures (80 °C, 100 °C, and 120 °C), a lifetime prediction model for EPDM sealing materials is derived using chemical reaction kinetics and the Arrhenius equation. The model is compared with the experimental results. The results show that the prediction model is highly reliable. The theoretical life of EPDM after thermal aging at 25 °C is 30.6 years, 53.1 years, and 89.1 years, respectively, when the compression set is 40%, 45%, and 50 %.

Recent development of metal-organic frameworks as a novel flame-retardant in polymeric applications

Abstract The increasing concern regarding hazardous fires related to polymeric materials has prompted numerous research into eco-friendly flame retardants. in recent years metal-organic Frameworks (MOFs) have emerged as promising flame-retardant materials, characterized by metal-containing units linked to organic linkers to create strong and porous crystalline frameworks. The organic ligands make MOFs possess significant surface area and adsorption properties desirable for different applications including flame retardancy. This paper gathers many of the recently published to discuss the use performance of polymer composites with MOFs for flame retardancy in comparison with polymeric composite materials without MOFs. Besides, a comparison based on mechanical, physical, and thermal properties shows the effect of MOF on the total effectiveness of the polymeric composite materials. This paper is of great interest to both the readers involved in the sphere of heat-resistance materials, encompassing contemporary advanced composite materials used for dampening hazardous fires. Furthermore, prospective trends, including the integration of innovative fillers such as MOFs in rubber composites such as NBR (Nitrile Butadiene Rubber), EPDM (Ethylene Propylene Diene Monomer), and silicone rubber, are deliberated upon.

Structural regulation and property balancing of ethylene‐propylene‐diene monomer‐based oil‐absorbing expandable rubber modified with flexible α‐olefins

AbstractTo regulate the comprehensive performance of ethylene‐propylene‐diene monomer (EPDM)‐based oil‐absorbing expandable rubber, a series of irradiated α‐olefin‐EPDM7001 rubbers (EOR7001‐X‐Y) are prepared. The influence of the carbon chain length and content of α‐olefins on the structure and properties of the rubber is systematically investigated. Results show that EOR7001‐X‐Y possesses a cross‐linked network structure, and its gel fraction decreases gradually with the increase in carbon chain length and content of α‐olefins. The incorporation of α‐octadecene successfully creates micro‐nanoscale porous structures within the rubber matrix, providing favorable conditions for oil absorption. The introduction of α‐olefins and changes in irradiation dose do not significantly affect the thermal stability of EPDM7001 rubber. The tensile strength slightly reduces, while elongation at break significantly increases, improving the deformation capability. EOR7001‐18‐20 demonstrates exceptional resistance to aging and withstands external forces even after oil absorption. This study supports the development of high‐performance oil‐absorbing expandable rubber.

The effect of nano-zinc oxide on the mechanical properties of the cured ethylene-propylene-diene monomer rubber with a semi-efficient vulcanisation system

The present investigation is dedicated to the impact of replacing conventional zinc oxide (ZnO) with nano-zinc oxide (nZnO) in ethylene-propylene-diene monomer (EPDM) rubber compounds. Multiple rubber compounds were prepared utilising conventional and nano-zinc oxides, followed by vulcanisation employing a semi-efficient vulcanisation system (SEV). Results indicate that nZnO promotes a more uniform dispersion within the rubber matrix compared to ZnO. Moreover, the incorporation of nZnO enhances the vulcanisation process, yielding a notable 27% increase in crosslink density. Nevertheless, the mechanical properties of the cured rubber, encompassing tear strength, hardness, tensile strength and elongation at break, remained either unaffected or exhibited slight deterioration. This observed discrepancy is ascribed to the inherent tendency of nZnO particles to self-aggregate, thereby disrupting the homogeneous distribution of the activator within the rubber matrix and fostering the formation of localised crosslink networks around the nano-particles. To overcome this challenge, the study proposes potential strategies, including nano-particle surface modification, optimisation of mixing parameters, and integration of compatibilisers, aiming to enhance the interaction between nZnO and rubber chains, mitigate agglomeration and facilitate a more even dispersion. The study suggests the potential of nZnO in augmenting the crosslinking efficiency of rubber compounds while emphasising the imperative need to address nano-particle agglomeration to optimise overall mechanical properties.

Properties of EPDM Nanocomposites Reinforced with Modified Montmorillonite.

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.

Recycling devulcanized EPDM to improve engineering properties of SBR rubber compounds

Ethylene propylene diene rubbers (EPDM) have gained substantial attention in automotive and industrial applications owing to their exceptional resistance against weathering and heat. Despite their advantages, the elastomeric nature of EPDM poses challenges in its recycling due to the presence of crosslinks in their chemical structure, preventing them from melting. To overcome this issue, devulcanized EPDM (EPDMd) has been developed, characterized by the effective breaking of these crosslinks. Our study focuses on common composites that include Styrene Butadiene Rubber (SBR), EPDM and silica, but with the incorporation of devulcanized EPDM (EPDMd).We have studied the mechanical, thermal, structural and dielectric properties of SBR composites containing EPDMd at variable compositions (0, 20, 40, 50, 60 phr). Employing techniques such as Thermogravimetric Analysis (TGA), Fourier Transform Infrared Spectropy (FTIR), and Scanning Electronic Microscopy (SEM), we have explored the microstructural changes driving the macroscopic effects on the measured properties.The results show that incorporating EPDMd improves the crosslinking degree and, at optimal 40 phr loading, significantly increases the mechanical properties of SBR matrix. The addition of SiO2, in general, reduce tensile strength and elongation, while increasing the Young's modulus, except for compositions around 40 phr EPDMd. The dielectric measurements are in concordance with the previous data, showing a moderation of the Maxwell–Wagner–Sillars (MWS) effect due to SiO2 in highly filled EPDMd composites at 40 phr EPDMd.

Impact of graphite nanoflakes and gamma radiation on the mechanical, electrical, and thermal properties of EPDM/modified BaTiO3 composites

The effect of graphite nanoflakes (GNFs)/modified barium titanate (MBT) hybrid fillers on the mechanical, electrical, and thermal properties of ethylene-propylene-diene monomer (EPDM) was extensively investigated in the current study. Moreover, the effect of gamma irradiation on the different properties of the prepared nanocomposites was investigated. To accomplish this goal, EPDM/MBT composites with various GNFs contents (0, 2, 4, 6, and 8 phr) were fabricated using a conventional roll mill. Graphite was expanded by heating and subsequently modified using tween 80 surfactant, resulting in the formation of GNFs. The presence of various functional groups on the surface of the modified BaTiO3 particles was verified by Fourier transform infrared spectroscopy (FTIR). The scanning electron microscopy (SEM) analysis revealed a uniform dispersion of GNFs in EPDM/MBT composites, with a concentration up to 6 phr. The study revealed that the mechanical properties of the nanocomposites were reinforced by the inclusion of GNFs up to 6 phr. The irradiated EPDM/MBT/6 phr GNFs nanocomposite exhibited the maximum elastic modulus value of 4.8 MPa, which was approximately 32 % higher than that of the corresponding unirradiated nanocomposite. The thermal conductivity of the irradiated EPDM/MBT/8 phr GNFs nanocomposite increased from 0.213 W/m.K to 0.260 W/m.K (22 %), while the dielectric constant increased from 4.475 to 5.551 (24 % increase) at 103 Hz as compared to the pure EPDM/MBT composite. The enhanced electric and thermal performance of GNFs can be attributed to the mobility of their π-electrons.

Low-energy micron dispersion of entangled polymers based on phase inversion composition of emulsion

This article aims to propose a low-energy method for micron dispersion of entangled polymers. We chose Ethylene-Propylene-Diene Monomer (EPDM) as the entangled polymer and acrylic esters as the dispersants to prepare the organic dispersion of the entangled polymer based on the theory that in-situ polymerization of acrylic esters had the higher solubility parameter than the original monomer. The dispersion process of entangled polymer was similar to the phase inversion of emulsion due to the maximum viscosity and minimum interfacial tension at the point of dispersion. Specifically, the average diameter of the dispersed entangled polymer was 5–6 μm. The system could still maintain excellent dispersion stability without additional dispersants. Rheology characterized that the introduction of aliphatic isocyanate derivatives reacting with hydroxyl groups in the polyacrylate to form the cross-linked skeleton could enhance the stability of the system. Excitingly, this organic dispersion allowed flexible printed circuit to fold at any angle and direction when used as the coating, and the coating still maintained excellent dispersibility, flexibility, insulation, and adhesion after aging tests. This low-energy method for micron dispersion of entangled polymers could expand their applications in coatings and other fields while maintaining their own characteristics.

Effect of twin-roll temperature and interface adhesion on ablative performance and char structure of ethylene propylene diene monomer-based ablative insulator

Effect of twin-roll temperature and interface adhesion on ablative performance and char structure of ethylene propylene diene monomer-based ablative insulator

Toward the production of bioblends for the automotive sector: Reuse of recycled polyamide 6,6 to prepare super‐tough biopolyethylene

AbstractPlastics reuse is essential for promoting a sustainable future, especially by mitigating environmental impacts. Recycled polyamide 66 (PA66r) was reused for the produce biopolyethylene (BioPE)‐based blends, aiming to obtain a super‐tough material. Initially, a premix of PA66r with maleic anhydride‐grafted ethylene–propylene–diene (EPDM‐MA) was obtained in an internal mixer. Subsequently, the BioPE/PA66r and BioPE/(PA66r/EPDM‐MA) blends were processed in a twin‐screw extruder and injection molded. The rheological, mechanical, thermal, thermomechanical, structural, and morphological properties were investigated. Torque rheometry indicated an increase in the viscosity of the BioPE/(PA66r/EPDM‐MA) blends compared to BioPE/PA66r, which was confirmed by a reduction in the melt flow index (MFI). EPDM‐MA promoted greater stability in BioPE/(PA66r/EPDM‐MA) blends during processing, reducing the degradation rate and molecular weight loss. The BioPE/(PA66r/EPDM‐MA) blend with the 70/(15/15)% composition exhibited super‐tough behavior, with 822.4 J/m impact strength and 233% elongation at break. Scanning electron microscopy indicated a fracture with high plastic deformation, elongated fibrils, and refined particles (0.64 μm), confirming the high toughness. Apparently, a core‐shell morphology was formed, which favored maintaining tensile strength, Shore D hardness, and heat deflection temperature comparable to pure BioPE. The results indicate potential for application in the automotive industry, contributing to reintroducing recycled material into the production chain.

Enhancing Flame Retardancy and Smoke Suppression in EPDM Rubber Using Sepiolite-Based Systems.

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.

Rubber compounds made of modified ethylene propylene diene monomer (EPDM) for laminated bearings with excellent anti-peel strength

In order to enhance the design life of laminated rubber bearings in the field of highway bridges in the plateau region, a novel laminated bearing was made by the modified ethylene propylene diene monomer (EPDM) rubber that combines both low-temperature and ageing resistance properties in this work. The modified EPDM also exhibit a high anti-peel strength with reinforced steel plate layer. Experimental and numerical investigations were carried out to evaluate the mechanical properties and failure conditions for the EPDM laminated bearing. The results indicate that the bearing with different shape factors exhibit good mechanical properties, and its key performance parameters such as compressive modulus and shear stiffness meet the requirements of the current specification for highway bridges. Meanwhile, we have established a quantitative relationship between the proportion of void area and the total local shear strain for EPDM laminated bearing, and found that when the proportion of void area reaches more than 32 %, some of the performance indexes of the bearing will exceeds the design limit. The above research results can be used as an important criterion for evaluating the performance of modified EPDM bearings.

Molecular Simulation Insights into Chemical-Grafted EPDM for Improving Charge Traps, Moisture Resistance, and Pyrolysis Tolerance

This study explores and verifies the chemical modifications achieved by grafting 4-formylcyclohexyl heptanoate (FH) and 4-(2,5-dioxopyrrolidin-1-yl) cyclohexane-1-carbaldehyde (CC) onto ethylene propylene diene monomer (EPDM) elastomer, a prevalent dielectric material used for reinforced insulation in cable accessories. Employing a rigorous theoretical methodology combining first-principles calculations, molecular dynamics, and Monte Carlo molecular simulations, we elucidate the intricate effects of these chemical-graft modifications on the polymeric structure of EPDM to resist charge transport, moisture-aging, and thermal impact of partial discharge. Our investigation uncovers the emergence of both shallow and deep charge traps within the material, effectively mitigating electron avalanche breakdown. Additionally, we scrutinize the influence of two proposed organic species, acting as grafting agents, on several crucial properties of EPDM including water adsorption uptake, heat capacity, molecular thermal vibration, and polymer pyrolysis. These modifications substantially bolster EPDM’s resistance to high-temperature electrical breakdown and water thermodynamic adsorption, while also enhancing its thermal stability, rendering the proposed chemical-graft modifications an effective way and underling mechanisms for ameliorating electrical insulation performances of EPDM elastomer. Our findings highlight the significant potential of graft modification in molecular structures through comprehensive molecular simulations, offering valuable insights for advancing competent elastomeric polymers in cable accessory insulation.

Rate-Dependent Tensile Properties of Aluminum-Hydroxide-Enhanced Ethylene Propylene Diene Monomer Coatings for Solid Rocket Motors.

Quasi-static and dynamic tensile tests on aluminum-hydroxide-enhanced ethylene propylene diene monomer (EPDM) coatings were conducted using a universal testing machine and a Split Hopkinson Tension Bar (SHTB) over a strain rate range of 10-3 to 103 s-1. This comprehensive study explored the tensile performance of enhanced EPDM coatings in solid rocket motors. The results demonstrated a significant impact of strain rate on the mechanical properties of EPDM coatings. To capture the hyperelastic and viscoelastic characteristics of EPDM coatings at large strains, the Ogden hyperelastic model was used to replace the standard elastic component to develop an enhanced Zhu-Wang-Tang (ZWT) nonlinear viscoelastic constitutive model. The model parameters were fitted using a particle swarm optimization (PSO) algorithm. The improved constitutive model's predictions closely matched the experimental data, accurately capturing stress-strain responses and inflection points. It effectively predicts the tensile behavior of aluminum-hydroxide-enhanced EPDM coatings within a 20% strain range and a wide strain rate range.

One facile route to prepare high‐performance radiation resistant EPDM rubber composites through graphite modification technology

AbstractModification and improvement of aging resistance in nuclear power environment for the ethylene‐propylene‐diene (EPDM) rubber has been attracting the attention of scientists. In this article, graphite modified EPDM composites (ultrafine graphite [UG]/EPDM) were prepared, and effect of graphite with sizes of 13, 2.6, and 1.3 μm on the processability, vulcanization parameters, mechanical properties, stability of radiation aging of EPDM composites were investigated, respectively. The results showed that EPDM rubber was an irradiated crosslinked polymer. The Mooney viscosity and crosslinking density of EPDM gradually increased with increasing graphite content under the effect of physical and chemical cross‐linking of graphite. The lamellar structure of graphite particles in the rubber matrix is beneficial to improvement of the mechanical properties and aging resistance of the EPDM composites and play a reinforcing role, and the sp2 hybrid structure of graphite can trap and quench free radicals, delayed the irradiation aging of EPDM. UG/EPDM composites irradiation stability was improved with increasing graphite dispersion in EPDM matrix. Under the cumulative irradiation dose of 1000 kGy, the tensile strength of blank sample and UG‐2.6 μm−10 decreased by 51.1% and 17.7%, respectively, and the hardness increased by 8.7% and 4.9%, respectively. The energy storage modulus and the corresponding glass transition temperature (Tg) of UG/EPDM composites enhanced with graphite, while the thermal stability of the composites was improved.

Prediction on the time-varying behavior of tunnel segment gaskets under compression

The compression force is a critical indicator for assessing the waterproofing capability of ethylene propylene diene monomer (EPDM) rubber gaskets, and the relaxation of EPDM gaskets under compression is a key factor contributing to water leakage in shield tunnels. In this study, detailed accelerated aging tests of gaskets with different precompression openings were conducted. Analytical method and simulation method for predicting the long-term performance of EPDM gaskets considering their different compression states were proposed. First, the compression curve of the gasket was divided into three stages to analyze the mechanism of compression force degradation in depth. Under the action of a compression force, the unrecoverable deformation caused by open holes shortened stage III of the compression curve, which constituted the primary factor influencing gasket compression force relaxation. In addition, the Arrhenius equation was used to establish a conversion relationship between the accelerated aging test conditions and actual service time, and an analytical expression (AE) method for predicting the compression force degradation pattern of gaskets was proposed. Finally, a finite element (FE) method based on the relaxation constitutive model was proposed, enabling simulation of deteriorating tunnel segment gasket performance under complex compression states. Then, the effectiveness and accuracy of the proposed relaxation model were validated by comparing the compression force curves and deformation states obtained from experiments and simulations. Based on the time-varying relaxation constitutive parameters, the variation in the compression force of EPDM gaskets with different joint openings over time was simulated. The results show that the minimum compression force retention rates of gaskets after 100 years of service predicted by the AE method and FE method are 28.5 % and 30.6 %, respectively. This study provides two effective means for predicting the long-term mechanical performance of compressed EPDM gaskets, offering pivotal insights for long-term waterproofing design of shield tunnel joints.