Ethylene Propylene Diene Monomer Elastomer Research Articles

Current Advancements in the Behavior Analysis of EPDM Elastomers in Peripheral Applications of the Cathodic Side of PEMFC Systems

This review examines the latest developments in the study of how Ethylene Propylene Diene Monomer (EPDM) elastomers behave in peripheral applications of Proton Exchange Membrane Fuel Cells (PEMFCs), specifically on the cathodic side. The review highlights the crucial role of EPDM in maintaining the integrity and efficiency of PEMFCs in challenging conditions characterized by varying temperatures, humidity, and acidic environments. The study examines the impact of various additives and vulcanization procedures on EPDM's mechanical and chemical properties, demonstrating enhancements in tensile strength, thermal stability, and chemical resistance. The study also investigates the compounding methods and selection of fillers, such as silica and carbon black, to optimize the performance of EPDM. Additionally, the effects of prolonged operational circumstances on EPDM's mechanical integrity and aging resistance in PEMFCs are being examined. This research emphasizes EPDM's suitability for long-term use in fuel cell systems. This review aims to guide the design of more durable and efficient PEMFC systems by optimizing the use of EPDM elastomers.

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.

Experimental Analysis of Watertightness Performance of Interfaces between Masonry and Steel Structures Subjected to Accelerated Aging

Steel buildings often experience failure at the interfaces between their vertical exterior enclosure systems (VEESs) and structural elements. This phenomenon generates various pathological manifestations in steel buildings, resulting in the precocious decay of the structure and the diminishment of its service life. The treatment of these interfaces is essential for ensuring their proper performance and watertightness, and to protect the durability of the steel structure. This paper proposes a method for treating common interface joints between masonry and steel structures with the application of an EPDM (ethylene propylene diene monomer) elastomer membrane. The main goal of this building technique is to ensure the durability and watertightness of the interface’s joints when they are subjected to aging triggered by heat exposure and thermal shock. The experimental models tested consisted of a steel frame and a conventional masonry vertical enclosure system with ceramic blocks plastered with cement mortar. The models were subjected to ten cycles of heat exposure and thermal shock for the purpose of simulating accelerated aging, followed by a watertightness experiment that simulated the action of both rain and wind pressure. The interfaces between masonry and the steel structure proposed in this study allowed adequate differential movements between the parts, without damage to joints and masonry. Only small cracks were observed in the outer test region of all of the interfaces tested. In the regions of the joints treated with the EPDM membrane, no alterations were visible to the naked eye. During the cycles of the heat exposure and thermal shock test, the maximum relative horizontal displacements observed in the joints were 0.743 mm for vertical joints and 0.230 mm for horizontal joints, indicating the accurate reproduction of the behavior expected from an untied interface. The results obtained in the previously mentioned watertightness test showed that no humidity stains were found on the inner face of any of the specimens, even after the continuous application of a pneumatic pressure of 400 Pa for eight hours. Therefore, the results indicated satisfactory performance in terms of durability and watertightness in all evaluated cases, indicating that the application of an EPDM membrane can be effective in preventing water leaks in the interfaces between masonry and steel elements, thus contributing to ensuring the steel structure’s durability.

The Effect of Cross-Linking Type on EPDM Elastomer Dynamics and Mechanical Properties: A Molecular Dynamics Simulation Study.

The cross-linking structure of the Ethylene-propylene-diene monomer (EPDM) is made up of a number of cross-linking types, including carbon atoms from the main chain or monomer and ether crosslinks formed during degradation. Through molecular dynamic simulations, the contribution of each type of cross-linked structure to the dynamics and mechanical properties of EPDM, the study’s focus, were investigated. Cross-linking between the tertiary carbons of two main chains, cross-linking at the monomer’s unsaturated position, ether cross-linking after oxidation, and other combinations of target cross-linked carbon atoms from different positions, totaling eight types of cross-linked types, were mixed with EPDM free chains in a 1:1 ratio to form eight types of cross-linked EPDMs. These varieties of cross-linked EPDMs were then compared to an uncross-linked EPDM in terms of density, radius of gyration, free volume, mean square displacement, and uniaxial tensile stress-strain curves. It was found that the cross-linking was always proven to have a favorable influence on mechanical characteristics; however, the relaxation inhibition effect varied. The cross-linking between the diene monomer at the C9 position resulted in a more flexible molecular shape and was more than double the free volume of the uncross-linked EPDM, resulting in an improved diffusion ability. The ether cross-linking produced by the oxidation of the side chain cross-linking improved the positive contribution to stiffness and enhanced the inhibitory impact on diffusion properties, whereas the main chain cross-linking had the opposite effect. The research presented in this study leads to a better knowledge of the microscopic aspects underlying EPDM performance.

Polycaryophyllene as a Promising Plasticizer for Ethylene Propylene Diene Monomer Elastomers

This work focused on the synthesis of polycaryophyllene (Pcar) with controlled molar mass through ring-opening metathesis polymerization of caryophyllene in the presence of styrene as a nonpolar chain transfer agent (CTA). The CTA easily allowed for tuning the molar mass of resulting Pcar from a molar mass of 2 × 104 g mol–1 in the absence of CTA to molar masses ranging between 9 × 102 g mol–1 and 6.5 × 103 depending on the molar ratio of monomer to CTA. As expected, the molar mass decrease affected the glass transition temperature (Tg) of styrene end-capped Pcar varying from −36 °C to a range between −40 and −65 °C. The Pcar with a low molar mass (Pcar@Sty#02) emerges as a promising biobased plasticizer candidate for the ethylene propylene diene monomer elastomer (EPDM) because it decreases EPDM Tg from −46 to −54 °C. The vulcanized plasticized EPDM with Pcar@Sty#02 showed improved flexibility compared to the one plasticized with the petroleum-based plasticizer or nonplasticized EPDM.

Relationships of tensile strength with crosslink density for the high‐carbon black‐filledEPDMcompounds with various softeners

AbstractEquilibrium swelling and rheological tests were adopted to systematically investigate the effects of softener type and dosage on the crosslink densities. The results turned out that the chemical crosslink density could be distinguished from the physical crosslink density by comparing the results of equilibrium swelling and rheological tests. The liquid butadiene (LB) as a softener leads to the greatest reduction in crosslink density, followed by polyethylene wax (PW) and paraffinic oil (PO). The tensile strength decreases with increasing PO content while shows peak values with increase of LB and PW contents. The dependencies of chemical crosslink density on the aging time under 150°C are quite different for the three softeners, which can be expected from the double crosslinking networks consisting of small softener and large main crosslinking networks. Further investigation has been performed to correlate the tensile strength with chemical crosslink density of ethylene propylene diene monomer elastomer vulcanizates. Three different linear relationships can be obtained for the softeners independent of the aging time. It can now be expected from this study that the role of some new softeners in rubber compounds is not only confined to plasticization but also forms crosslinking networks in the peroxide‐cured rubbers.

Quantifying Chemical Composition and Cross-link Effects on EPDM Elastomer Viscoelasticity with Molecular Dynamics

To understand the effect of chemical composition, cross-link density, and microstructure on the linear and nonlinear viscoelasticity of ethylene propylene diene monomer (EPDM) rubber, we carried out high-frequency oscillatory shear molecular dynamics simulations at varying shear strain rates. Sweeping through different EPDM compositions with varying ethylene, propylene, and diene ratios, a positive correlation was observed between the ratio of the propylene monomer and the complex shear modulus of EPDM in the high-frequency glassy regime. For small deformations in this regime, we found that the simplest measure of local molecular stiffness, namely, the Debye–Waller factor, is predictive of the complex shear modulus and loss modulus of 20 unique systems with distinct compositions and cross-link densities. Polymer design parameters that reduce the Debye–Waller factor, including cross-linking or increased propylene content generally, result in higher moduli. Remarkably, large-amplitude oscillatory shear simulations revealed that dissipation becomes strongly influenced by polymer entanglements, which results in divergent optimal compositions for small-strain vs large-strain applications of EPDM. Utilizing time–temperature superposition and varying strain rates in simulations, we were able to capture rheological properties over 6 orders of magnitude in frequency. The data was captured well using a Rouse model superposed with a stretched exponential function, which was used to predict key constants that determine the mechanical behavior in these regimes. Our findings establish a chemistry-specific molecular simulation approach for capturing the constitutive behavior of elastomers and pave the way for multiscale analyses linking composition and microstructure to performance.

Tuning the Ablation, Thermal and Mechanical Characteristics of Phenolic Resin Reinforced EPDM Ultra-High Temperature Insulation

The present research reports the influences of variant phenolic resin concentrations on the thermo-mechanical and ablation characteristics of ethylene propylene diene monomer (EPDM) elastomer. Backface temperature acclivity (BTA), charring rates, and insulation indexes were executed for the fabricated composite specimens. It was noticed that BTA was enhanced while linear/radial/mass ablation rates were significantly diminished with increasing concentration of phenolic resin (PR) in base matrix (elastomeric polymer). The composite (30wt%PR/EPDM) has 25% high thermal endurance compared to virgin EPDM composite. Thermal conductivity was increased with increasing PR to EPDM ratio. PR incorporation has remarkably enhanced the ultimate tensile strength of the EPDM elastomer. An efficient improvement in elastomeric hardness was also observed with increasing PR contents in EPDM matrix. Scanning Electron Microscopy (SEM) results showed the porosity generation and polymer melting during ablation.

Tritium Effects on Aromatic Carbon–Loaded Polymers

By incorporating carbon nanotubes (CNTs) and graphene nanomaterials with aromatic sp2 carbon structures, we have specifically tuned filled ethylene propylene diene monomer elastomer (EPDM) seal and gasket composite materials for radiation resistance. Our results show that CNTs and graphene have an increased ability to stabilize the EPDM matrix compared to standard carbon black (CB) as a radiation-resistant filler. Graphene outperforms both CNT and CB fillers when considering surface damage under conditions where beta exposure is an issue. Both graphene and CNT fillers offer significantly reduced changes in glass transition temperature under prolonged exposure to tritium compared to CB-filled standards, with a 2.5-fold and almost 5-fold reduction, respectively. Thus, CNT- and graphene-filled O-ring materials could be designed that would maintain acceptable seals significantly longer than currently used composites.

Morphology, barrier and electrical properties of oil-extended EPDM/nanographite nanocomposites

Nanocomposite samples were prepared by introducing nanographite as reinforcing filler in oil-extended ethylene propylene diene monomer (EPDM) matrix and characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to evaluate the morphology and degree of dispersion. The effects of nanographite concentration on mechanical properties of EPDM nanocomposites have been studied. Electrical properties of EPDM/nanographite nanocomposites have also been studied as a function of frequency (0.1–105 Hz) and nanofiller concentrations. Percolation theory has been used to study the frequency dependent alternating current (AC) conductivity. The study shows percolation threshold near 4% nanographite concentration in oil-extended EPDM elastomer.

Degradation of EPDM and FPM elastomers irradiated at very high dose rates in mixed gamma and neutron fields

Elastomers are widely used in radioactive environments, where ionizing radiations induce a deterioration of their properties due to degradative phenomena occurring in the polymer structure. Their radiation resistance is usually assessed using γ‐rays and relatively low dose rates, but in actual applications, they are often exposed to mixed radiation fields and higher dose rates. Ethylene propylene diene monomer (EPDM) is known for its excellent resistance to γ‐rays but absorbs a larger dose by neutron interactions than fluoroelastomer (FPM). In this work, EPDM and FPM were irradiated in mixed neutron and gamma fields, using high dose rates (from 22 to 700 kGy h−1) and total absorbed doses between 0.2 and 3.5 MGy. The effects of irradiation were assessed by swelling tests, differential scanning calorimetry analysis and dynamic mechanical thermal analysis, and tensile tests. The results show that, even if irradiations were carried out in air, degradation took place under nonoxidative conditions owing to the high dose rates employed. Under such conditions, crosslinking is the dominant radiation‐induced reaction in both elastomers. Moreover, material degradation seems to be influenced mostly by the total absorbed dose and not by the type of radiation. Contrary to what observed at the lower dose rates employed with γ‐rays, major dose rate effects are not observed. POLYM. ENG. SCI., 59:2522–2532, 2019. © 2019 Society of Plastics Engineers

Jojoba Oil (Simmondsia Chinensis) as a Natural Plasticizer for Ethylene Propylene Diene Monomer Elastomers

Jojoba oil (JO) as natural plasticizer for EPDM rubber was studied and compared with paraffin oil (PO) at 5, 10 and 20 phr, using sulfur and peroxide crosslinking systems. Vulcanization curves for sulfur systems had the lowest torque value for JO, 26 dNm, whereas for PO was 60 dNm. For peroxide systems, the lowest torque value was for PO compounds, 18 dNm, whereas for JO was 21 dNm. Stress values for sulfur systems were 12-18 MPa, and for peroxide systems, 14-23 MPa; 23 MPa was for JO compounds . Highest crosslink density values were for sulfur systems with PO, >1000 mol/m3. TGA indicated volatilization of PO, 250-280 °C and for JO at 400 °C, evidencing better EPDM thermal stability with JO. Results showed greater plasticizing effect of JO when using sulfur as cross-linking agent, and its possible use as renewable plasticizer for EPDM, reducing the concentration of plasticizer in formulations.

Evaluation of liner hanger seal assembly and cement sheath as a dual barrier system: Implications for industry standards

Liner hanger seal assembly and cement sheath are essential barrier elements for well drilling and completions. During installation, the liner hanger seal assembly is set up-stream to the cement column. This arrangement prevents the evaluation of both the liner hanger seal assembly and cement sheath independently. Currently, there are no testing procedures, industry standards, or regulatory guidelines for testing this type of dual barrier system independently.The primary objective of this study is to establish that cement sheath can act as a secondary barrier element in a dual barrier (elastomer seal and cement sheath) zonal isolation system, if the elastomer seal (primary barrier) is faulty. In the context of this study, the term "barrier" describes the use of cement sheath and elastomer sealing element in a liner hanger to prevent uncontrolled migration of formation fluid to a shallow formation or surface facilities. Another objective is to evaluate the effect of using an anti-gas migration additive on cement sealability. To achieve these objectives, experimental testing procedures were developed to evaluate the performance of a liner hanger seal assembly and cement sheath. Two experimental scenarios were considered in this study. The first scenario included testing faulty ethylene propylene diene monomer (EPDM) elastomer with neat Class H cement and the second scenario included testing faulty EPDM elastomer and Class H cement mixed with a commercial gas migration control additive. The tests were conducted at different pressures and wait on cement (WOC) intervals.The results revealed that neat Class H cement cannot act as a secondary barrier and prevent gas migration in the case that the primary barrier (elastomeric element of the liner hanger) is faulty. The cement slurry with the commercial gas migration control additive can act as a secondary barrier in case the primary barrier is faulty. The results also showed that WOC time improves cement sheath sealability. In addition, pipe material and surface roughness play key roles in the cement slurry bonding process. The major addition to the literature from this study is that for cement sheath to be considered a secondary barrier element in a dual barrier zonal isolation system, it must contain a specific anti-gas migration additive in addition to other cement additives. This specification should be included as a standard regulatory practice and should be adopted for every well section.

New mathematical models for predicting the lifetime of EPDM insulators: Effect of elongation at break on the kinetic degradation of EPDM insulators subjected to thermo-oxidation

Ethylene propylene diene monomer (EPDM) is an important polymer extensively exploited in plasturgy. However, relatively few studies have been carried out to predict the lifetime of EPDM in different climatic conditions particularly, thermo-oxidation. Based on this realization, the aim of the present work was to develop mathematical models for predicting the lifetime of EPDM elastomers, used for insulation of electric cables. The kinetic degradation of EPDM insulators, by monitoring change in a physical property (elongation at break test “ℇr”), was studied by following its thermo-oxidative aging (70, 90, 110 and 130 ° C in air circulating oven). The multiple linear regression analysis (MLRA), solved by the Cholesky method, was the mathematical approach developed in the modeling of the kinetic degradation. In this study, we used two insulators materials when the first insulator contained an amorphous EPDM and the second contained a semi-crystalline EPDM. The results showed that the polynomial models developed to predict elongation at break were reliable for both insulators under thermo-oxidation. The half-life times predicted by the mathematical models was found to be statistically significant (p< 0.05). In conclusion, the mathematical models developed in our study could be used confidently to predict the lifetime of EPDM elastomers.

Interplay between key variables of peroxide cured EPDM and evaluation of electromechanical efficiency for MV cables

ABSTRACTExtensive work has been done on ethylene‐propylene‐diene monomer (EPDM) vulcanizates and the main factors influencing their cure efficiency. However, very little attention has been given to the evolution of material properties and the interplay between key variables formulation. The effect of ethylene/propylene content and concentration of peroxide and type on viscoelastic and dielectric properties of EPDM elastomers was investigated using dynamic mechanical analysis and electric property measurements at room temperature. In order to compare results, these measurements were obtained by FTIR spectroscopy. Differences between real and imaginary (loss) part of the permittivity of EPDM/ dicumyl peroxide (DCP) composites were more significant than those in EPDM/di(tert‐butylperoxyisopropyl)benzene (DTBPIB) composites. For peroxide DTBPIB, the dielectric percolation limit moves further with the increase of ethylene content of EPDM. The dielectric percolation limit of the peroxide DTBPIB is found to be approximately 60 g at a 75% of ethylene in EPDM. The FTIR analysis showed that a termoxidative degradation was promoted at mixes with peroxide DCP at 45 and 75% of ethylene in EPDM. Therefore, we could interestingly show the decrease in electrical properties particularly associated with termoxidative degradation of peroxide DCP. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46139.

Tailoring in thermomechanical properties of ethylene propylene diene monomer elastomer with silane functionalized multiwalled carbon nanotubes

ABSTRACTThe incorporation of silane treated multiwalled carbon nanotubes (S‐MWCNTs) is used as an effective path for tailoring thermomechanical properties of ethylene propylene diene monomer (EPDM). In this study, S‐MWCNTs were introduced into EPDM using internal dispersion kneader and two roller mixing mill. By altering the mass ratio of S‐MWCNTs from 0 to 1, thermal conductivity, thermal stability and phase transition temperatures and their respective enthalpies are discussed of the fabricated nanocomposites. It is observed that silane modification improves their dispersion and increases the interfacial bonding between MWCNTs and polymer matrix. Scanning electron microscopy along energy dispersive spectroscopy analysis is performed to confirm the silane functionalized MWCNTs are selectively distributed in the host polymer. More importantly, an important increase in mechanical properties like ultimate tensile strength and hardness is achieved through introducing silane functionalized MWCNTs. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43221.

Miscibility, Phase Separation, and Phase Settlement Dynamics in Solutions of Ethylene–Propylene–Diene Monomer Elastomer in Propane +n-Octane Binary Fluid Mixtures at High Pressures

Miscibility and phase separation of ethylene–propylene–diene monomer (EPDM) elastomer at a polymer concentration of 11.7 wt % in n-octane (61.9 wt %) + propane (26.4 wt %) have been explored over a wide range of temperatures up to 187 °C and pressures up to 200 bar. Experiments were carried out using a new system that allows assessment of volumetric properties, thermodynamic phase boundaries, phase settlement times, and the mechanistic details of phase separation all in the same instrument. The system involves a novel, dual-piston variable-volume cell with two pairs of sapphire windows. One pair of the windows is used for the measurement of the transmitted light intensities, while the other pair is used for the measurement of scattered light intensities from a He–Ne laser source. Piston positions are continuously recorded with two dedicated linear variable differential transformers, which allow continuous determination of the solution densities as a function of pressure at a given temperature. The solutio...

A critical analysis of the effect of crosslinking on the linear viscoelastic behavior of styrene-butadiene rubber and other elastomers

The linear viscoelastic behavior in dynamic shear and tensile creep at temperatures from −30 to 70 °C is measured for an styrene–butadiene rubber (SBR) elastomer cured with dicumyl peroxide to crosslinking densities between 0 and 23.5 × 10−5 mol/cm3. The G′, G″, and tan δ isotherms are analyzed by time–temperature superposition (TTS), where the tan δ master curves are consistent with those of Mancke and Ferry. However, to achieve the TTS in the lightly crosslinked SBR systems, an anomalous vertical shift is required in the narrow temperature region from 10 to 30 °C. The vertical shift factor in this temperature region is not the standard from rubber elasticity. No anomalous behavior is detected in the equilibrium modulus, which is a linear function of temperature in accordance with the classical theory of rubber elasticity. In contrast to SBR, standard vertical shifts are required to effect TTS for uncrosslinked polybutadiene and an ethylene propylene diene monomer elastomer. © 2013 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013

Use of Differential Scanning Calorimetry (DSC) in the Characterization of EPDM/PP Blends

New polyolefinic thermoplastic elastomers based on the ethylene–propylene-diene monomer (EPDM) and polypropylene (PP) containing an EPDM elastomer of the last generation (Nordel NDR 47130), obtained by polymerization in the gaseous phase with metallocene catalysis, were prepared and characterized. The melting and crystallization behavior of these blends was investigated by differential scanning calorimetry. It is observed that the melting temperature, crystallization temperature, and crystallinity degree increase with an increase of PP loading. The influence of the blend composition on the physico-mechanical characteristics was discussed using statistical processing of the experimental data. Two compatibilizing procedures were utilized to improve the physico-mechanical characteristics of the samples: an addition method using different compatibilizing agents and dynamical vulcanization with three types of crosslinking systems. Significant improvements of the tensile strength and tear strength were noted by dynamic crosslinking, and the best results were obtained using a crosslinking system based on phenolic resin and tin chloride.

Jamming in Filled Polymer Systems

AbstractAfter an introduction into the general characteristics of the jamming behavior, two filler flocculation experiments on a polycarbonate melt filled with multi‐walled carbon nanotubes and on a silica‐filled ethylene propylene diene monomer elastomer are presented. We propose that these experiments can be regarded as jamming phenomena. The experimental data are successfully modeled using the power saturation equation. Further insights into the physics of such jamming processes have been obtained with the help of X‐ray photon correlation spectroscopy experiments.