Filled Ethylene Propylene Diene Monomer Research Articles

Crack propagation in filled elastomers: 3D study of mechanisms involving the filler agglomerates

This paper presents the impact of Carbon Blacks agglomerates, at different concentrations, on crack propagation mechanisms in a Carbon black (CB) filled Ethylene Propylene Diene Monomer (EPDM) elastomer. As shown by Transmission electron microscopy, these CB agglomerates (CBaggl) consist of aggregates clusters with interpenetrating elastomer, and for this reason, are soft and deformable. Crack tip observation using X-ray tomography demonstrates that these CBaggl can either undergo fracture or arrest/ deviate a crack during its propagation. This causes higher energy dissipation at the crack tip, which contributes to the dissipative component of the strain energy release rate G. For this reason, it is found that among the two materials tested with a significant amount of CBaggl (more than 3%), the material with the highest concentration has a slower crack propagation speed at high G.

Computational fluid dynamics modeling of multicomponent elastomeric complex profile while flowing through extrusion die

Extrusion is one of the most efficient and widely used methods for producing long elastomeric profiles, particularly for automotive industries. These include mono-component glass run, co-extrudate, multi-component, metal-reinforced rubber, and cellular elastomeric profiles. Die swell and the interface disturbance between the fluids creates additional complexities while designing an extrusion die for elastomeric products. The extrudate deformation depends on die geometry, processing parameters, and material properties of the elastomeric compound. In this study, the 3D model having three flow channels is constructed to perform the multi-component extrusion simulation with the help of computational fluid dynamics. Three different configurations of flowing material are considered; first for all the flow channels having the same material, second for two channels having the same material, and third for all the flow channels having different materials. The extrusion simulation was performed using shear rate dependent viscosity model and temperature-dependent viscosity model to compute the extrudate deformation along with the interfaces on carbon black filled ethylene propylene diene monomer rubber (EPDM) based elastomeric compound for a multi-component elastomeric profile. Moreover, the simulated results show that the extrudate having different materials possesses lower structural stability compared to the other two extrudates. Finally, the simulation carried out with a complex-shaped multi-component elastomeric profile revealed a good agreement with the structural profile of the physical extrudate.

Curing, thermal, tensile and flammability characteristics of sepiolite/ethylene propylene diene monomer rubber composites with glut palmitate salt and silane coupling agents

AbstractThe main objective of this work is to compare the effectiveness of a newly synthesized glut palmitate (GP) salt and a commercially available (3‐aminopropyl) trimethoxysilane (APTMS) as coupling agents in sepiolite (SEP) filled ethylene propylene diene monomer (EPDM/SEP) composites. The unmodified and modified composites with different amounts of SEP were prepared with an open two‐roll mill and the morphology, cure characteristics, tensile properties, flammability, and thermal stability were studied. Fourier transform infrared spectroscopy (FTIR) analysis indicated shifting of the related absorption peaks and confirmed the interaction between composite with the GP salt and APTMS and the successful modification of sepiolite particles in EPDM/SEP composites. The maximum torque (MH), scorch time (ts2) and cure time (t90) of the modified EPDM composites decreased with both coupling agents. Thermal stability reduced in the presence of coupling agents but the reduction is more pronounced in the composite with GP salt due to low‐temperature degradation of the fatty acid. Compared with unmodified EPDM/SEP, the tensile strength of the modified EPDM/SEP with GP and APTMS enhanced by 15% and 52%, respectively but both elongation at break and modulus were lowered. GP and APTMS were efficient coupling agents in linking the SEP and EPDM matrix, reducing the rubber‐filler interaction (Qf/Qg) from 1.00 for the EPDM/SEP composites to 0.76 and 0.64 for the EPDM/GP/SEP and EPDM/APTMS/SEP composites, respectively.

Effects of nanocrystalline calcium oxide particles on mechanical, thermal, and electrical properties of EPDM rubber

In this research, the effect of calcium oxide (CaO) nanocrystalline particles filled ethylene propylene diene monomer (EPDM) rubber composites is investigated, at different weight percentages (1.0, 2.0, 4.0, and 8 wt%) of CaO nanocrystalline particles using two methods of mixing. In one case conventional mixing on twin roll-mill was used, in the other case ultrasonic mixing as a pre-mixing was applied. CaO particles are synthesized by the precipitation method. The average crystallite size of CaO is 100 ± 20 nm. Adding CaO nanocrystalline particles increases the thermal stability of EPDM and the glass transition temperature. The hardness of EPDM rubber gradually increases with increasing the amount of CaO particles, the maximum hardness 64.2 observed in 8 wt% of CaO particles for both cases almost 26% higher than neat EPDM. Tensile strength decreases, while the maximum % modulus of the ultrasonic mixed sample was 1.48 MPa which is 24% higher than EPDM.

A mixed phase-field fracture model for crack propagation in punctured EPDM strips

In this work, we present crack propagation experiments evaluated by digital image correlation (DIC) for a carbon black filled ethylene propylene diene monomer rubber (EPDM) and numerical modeling with the help of variational phase-field fracture. Our main focus is the evolution of cracks in one-sided notched EPDM strips containing a circular hole. The crack propagation experiments are complemented with investigations identifying the mechanical material properties as well as the critical strain energy release rate. For simulating the evolution of cracks with a given notch, phase-field fracture modeling is a popular approach. To avoid volume-locking effects considering fractures in nearly incompressible materials, a quasi-static phase-field fracture model in its classical formulation is reformulated with the help of a mixed form of the solid-displacement equation. The newly established mixed phase-field fracture model is applied to simulate crack propagation in punctured EPDM strips by using the experimentally identified material parameters with mixed finite elements. To discuss agreements and point out challenges and differences, the crack paths, the maximal force response, the traverse displacement at the crack start, as well as force–displacement curves of the experimental and numerical results are compared.

Thermal and Physico-Mechanical Properties of Irradiated Aluminum Oxide Filled Ethylene Propylene Diene Monomer Rubber Composites

Composites from ethylene propylene diene monomer (EPDM) rubber filled with different concentrations 20, 40, and 60 parts per hundred rubber (phr) of aluminum oxide (Al2O3) were prepared. The samples were vulcanized by gamma irradiation at doses (50,100, 150, and 200) kGy. The effects of irradiation doses and Al2O3 contents on the mechanical prorerties (particularly tensile strength, elongation at break % and hardness), physical properties (volume fraction and crosslinking density), thermal properties was studied by thermogravimetric analysis (TGA) and fire resistance was tested using Limiting Oxygen Index (LOI) and rate of burning methods of EPDM and its composites were studied. The results indicated that the improvement of mechanical as well as, physical properties occurred by increasing the concentration of Al2O3 (except the tensile strength values, where the highest values were obtained at concentration 20 phr Al2O3 in the composite irradiated at 100 kGy). The thermal stability and fire retardancy properties of the prepared composites were improved by increasing Al2O3 concentration. Generally, the addition of Al2O3 and gamma irradiation has improved composite’s performance. This is suitable for preparing products of rubber serving in dynamic conditions, with longer expected service life

Crack path comparisons of a mixed phase‐field fracture model and experiments in punctured EPDM strips

AbstractWorking on quasi‐static phase‐field fracture modeling in nearly incompressible solids for crack propagation is a challenging task. To avoid arising locking effects therein, a mixed form for the solid displacement equation is developed, resulting in two unknowns: a displacement field and a hydro‐static pressure variable. In order to fulfil an inf‐sup condition, stable Taylor‐Hood elements are employed for the displacement‐pressure system. The irreversibility condition of the crack evolution is handled by help of a primal‐dual active set method. To get both a sharper crack and reasonable computational costs, adaptive meshes are used based on a predictor‐corrector scheme. The crack paths from the numerical simulations are compared on the experimentally observed crack paths in carbon black filled ethylene propylene diene monomer (EPDM) rubber strips. The punctured EPDM strips with a hole and a given notch at different heights are stretched till total failure.

Effect of the Strain Rate on Damage in Filled EPDM during Single and Cyclic Loadings.

The effect of the strain rate on damage in carbon black filled Ethylene Propylene Diene Monomer rubber (EPDM)stretched during single and multiple uniaxial loading is investigated. This has been performed by analyzing the stress–strain response, the evolution of damage by Digital Image Correlation (DIC), the associated dissipative heat source by InfraRed thermography (IR), and the chains network damage by swelling. The strain rates were selected to cover the transition from quasi-static to medium strain rate conditions. In single loading conditions, the increase of the strain rate yields in a preferential damage of the filler network while the rubber network is preserved. Such damage is accompanied by a stress softening and an adiabatic heat source rise. Conversely, increasing the strain rate in cyclic loading conditions yields in a filler network accommodation and a high self-heating whose combined effect is proposed as a possible cause of the ability of filled EPDM to limit damage by reducing cavities opening during loading, and favoring cavities closing upon unloading.

The Effects of Epoxidised Natural Rubber (ENR-50) on Cure Characteristics and Tensile Properties of Recycled Natural Rubber Catheter Filled Ethylene Propylene Diene Monomer (EPDM) Vulcanizates

The effect of epoxidised natural rubber (ENR-50) on cure characteristics and tensile properties (tensile strength, modulus at 100% elongation and elongation at break) of recycled natural rubber catheter filled ethylene propylene diene monomer (EPDM) vulcanizates were studied. The scorch time, t2 of EPDM/NRr blends with and without ENR-50 increased as NRr content increased while the cure time, t90 is decreased. However, with the presence of ENR-50 in EPDM/NRr blends, the t2 was longer and t90 was shorter than the uncompatibilized EPDM/NRr blends. The minimum torque, ML, of EPDM/NRr blend with and without ENR-50 relatively increased while maximum torque, MH, decreased with increasing NRr content. With the presence of ENR-50, the compatibilized EPDM/NRr blends exhibit a lower value of ML and MH compared with uncompatibilized blends. The incorporation of ENR-50 in EPDM/NRr blends enhanced the tensile strength and tensile modulus of compatibilized EPDM/NRr blends compared to uncompatibilized EPDM/NRr blends. The elongation at break (Eb) of compatibilized EPDM/NRr blends is lower than the uncompatibilized EPDM/NRr blends at all blend ratios. This indicated that ENR 50 improved the curing characteristics and tensile properties of the compound.

Thermal insulation behaviour of Ethylene propylene diene monomer rubber/kevlar fiber based hybrid composites containing Nanosilica for solid rocket motor insulation

AbstractThe current research discusses the properties of an elastomeric heat‐shielding material, based on nano‐silica (NS) filled ethylene propylene diene monomer (EPDM) rubber/Kevlar fiber (KF) hybrid composites. The developed elastomeric insulating material consists of an aromatic polyamide fiber (KF) and silica nanoparticles. An in‐depth analysis of mechanical properties, density, coefficient of thermal expansion, thermal conductivity, thermogravimetric analysis, and heat release rate of the insulating materials ‐was performed. TEM micrograph represents an excellent distribution of nanoparticles in the EPDM matrix. The improvement in the mechanical and the flame retardancy of the NS filled EPDM/KF hybrid composite insulations is based on the fiber/matrix adhesion. Maleic anhydride grafting confers polarity to the nonpolar rubber matrix. The char residues of the insulations inspected by scanning electron microscopy and energy dispersive spectroscopy are depicting a rigid and rough surface by the optimal composites, which can aid in better insulation. The optimal formulation of the hybrid composites exhibited a 220% enhancement in char residue with improved thermal stability and mechanical properties.

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.

Effects of peroxide and phenolic cure systems on characteristics of the filled ethylene–propylene–diene monomer rubber (EPDM)

ABSTRACTThe effects of three curing systems, peroxide, peroxide–phenolic combination, and phenolic on selected properties of cured carbon black‐filled ethylene–propylene–diene monomer rubber (EPDM) were investigated. The cured rubbers immersed in hot amine solution to evaluate their suitability for seal and gasket industry at elevated temperature and amine environments. These tests were essential for evaluating the durability of the gasket in a gas refinery. The Fourier transform infrared spectroscopy spectrums revealed that the phenolic crosslink was constructed between rubber macromolecules during the curing process. The changing curing system from peroxide to peroxide–phenolic and phenolic increased the glass transition temperature of the filled cured rubbers between 3 and 5 °C. There was not any significant difference between thermogravimetric analysis thermographs of the selected cured rubbers with various cure systems and the residues ranged between 45% and 47%. Unlike of peroxide curing system, a dual phase was observed from scanning electron microscopy micrographs for peroxide–phenolic and phenolic cure systems. The phenolic cure system was not beneficial for rubber curing although, it reduced scorch time of the curing process. For the most studied mechanical properties, phenolic cure system deteriorated mechanical properties for both, aged and unaged cured rubbers. Increasing the amount of diene monomer in EPDM structure was beneficial for phenolic rubber cure system. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46213.

Curing Characteristics and Tear Properties of Bentonite Filled Ethylene Propylene Diene (EPDM) Rubber Composites

The effect of bentonite clay loading on curing characteristics and tear strength of bentonite filled ethylene propylene diene monomer (EPDM) composite were studied. Compounding was carried out on two-roll mill and vulcanization was done at 1500C. Torque values, scorch time and optimum cure time of the prepared rubber compound were assessed by using Mosanto Disc Rheometer (MDR 2000). Results indicated that the maximum torque of EPDM/Bt composite decreases at high bentonite loading. Increasing in values with increasing bentonite loading was recorded for minimum torque and optimum cure time of EPDM/Bt composite. The increase is related with the increase in viscosity due to the increasing of bentonite clay loading in EPDM matrix. Scorch time was found to be decreasing up to 30 phr bentonite clay. Results also show that tear strength of EPDM/Bt composite increased with increasing bentonite loading up to 90 phr. The reason is probably due to agglomeration occur causes the reduction in properties at high loading above 90 phr bentonite clay. The scanning electron microscopy (SEM) of tear fracture surface of EPDM/Bt composite illustrated that with increasing bentonite loading up to 90 phr bentonite clay, a better dispersion of bentonite clay is achieved as compared to lower loading, resulting in high tear strength value for EPDM/Bt composite.

Compressive char strength of thermoplastic polyurethane elastomer nanocomposites

This research encompasses the study of testing protocols and the design of sensors for evaluating the compressive strength of the char layer of ablative material used in solid rocket motors (SRMs). The testing protocol that has been developed is the continuation of previous work for determining the compressive strengths between different SRM insulation materials. A crushing test method was further developed, and a sensor platform was assembled to perform the tests. The test procedure consists of measuring the amount of force required to crush a given area of the charred sample for a specified depth. The test was repeated for the industry standard Kevlar®‐filled ethylene propylene diene monomer rubber and thermoplastic polyurethane elastomer nanocomposite with different weight loading of multi‐walled carbon nanotubes, montmorillonite nanoclay, and carbon nanofibers. The energy of destruction or energy dissipated was quantified to determine which ablative exhibited the best performance. Maximum force was also recorded as a secondary quantity to determine char strength. The proposed test method is fully automated to ensure repeatability of each measurement and to remove the potential for human‐induced error. Because char layer thickness varies depending on the material, a method of differentiating neat material from char was proposed and explored. The introduced procedure also represents a novel and unique approach to solve the problem of the determination of the char strength. Copyright © 2014 John Wiley & Sons, Ltd.

Improvement of the mechanical properties of carbon black-filled ethylene propylene diene monomer using a metallic acrylate salt as filler

The effects of aluminum triacrylate on vulcanization, mechanical and morphological properties of filled peroxide-cured ethylene-propylene-diene rubber reinforced with carbon black are investigated. Curing kinetics is studied by rheometer and the results indicate that the curing characteristics are influenced by combination of conventional filler (carbon black) and reactive filler (aluminum triacrylate), because the former one enhances the physical cross-linking and the latter one introduces the ionic cross-linking. The results obtained show that the tensile strength, modulus, hardness and cross-link density were tremendously increased with increase of aluminum triacrylate loading in carbon black–filled ethylene propylene diene monomer. Moreover, the observation on the compounds showed that introduction of aluminum triacrylate reduces the elongation at break, resilience and abrasion of carbon black–filled ethylene propylene diene monomer. Morphology of the fractured surfaces of ethylene propylene diene monomer/carbon black/aluminum triacrylate composites was studied by scanning electron microscope. The morphological study indicates that interaction between the fillers and ethylene propylene diene monomer matrix has been improved by substitution of aluminum triacrylate filler with carbon black. Thus, the formation of ionic cross-links structures from both homo-polymerization aluminum triacrylate and graft co-polymerization of it onto the ethylene propylene diene monomer were the main reasons for the significant improvement in mechanical properties of ethylene propylene diene monomer/carbon black composites.

Preparation of nanoalumina/EPDM composites with good performance in thermal conductivity and mechanical properties

AbstractIn this paper, nanoalumina (Al2O3) highly filled ethylene propylene diene monomer (EPDM) composites are prepared, and the mechanical (static and dynamic) properties and thermal conductivity are investigated systemically through various characterization methods. Furthermore, influences of in situ modification (mixing operation assisted by silane at high temperature for a certain time) with the silane‐coupling agent bis‐(3‐triethoxy silylpropyl)‐tetrasulfide (Si69) and stearic acid (SA) pretreatment on the nano‐Al2O3 filled composites are as well investigated. The results indicate that nano‐Al2O3 particles can not only perform well in reinforcing EPDM, but also improve the thermal conductivity significantly. Assisted by in situ modification with Si69, the mechanical properties (especially dynamic mechanical properties) of the nano‐Al2O3 filled composites are improved obviously, without influencing the thermal conductivity. By comparing to the traditional reinforcing fillers, such as carbon black (grade N330) and silica, in situ modified nano‐Al2O3 filled composites exhibit excellent performance in mechanical (static and dynamic) properties as well as better thermal conductivity, especially lower compression heat build‐up and better fatigue resistance. In general, our work indicates that nano‐Al2O3, as the novel thermal conductive reinforcing filler, is suitable to prepare rubber products serving in dynamic conditions, with the longer expected service life. Copyright © 2010 John Wiley & Sons, Ltd.

Preparation and properties of polytetrafluorethylene filled ethylene–propylene–diene monomer composites

AbstractEthylene–propylene–diene monomer/polytetrafluorethylene (EPDM/PTFE) composites based on EPDM and electron beam irradiated PTFE powders (MS‐II, MS‐III, and MS‐V, with mean diameter 5 μm, 1 μm, and 0.1 μm, respectively) were prepared by a mechanical compounding technique. The curing characteristics, morphologies, mechanical properties, and abrasion behaviors of these composites were investigated. The curing measurements indicated that the addition of lower loading of MS‐III or MS‐V enhanced the lubrication of EPDM compounds and delayed the curing process. The morphological structure of the composites demonstrated that the MS‐III and MS‐V were uniformly dispersed in EPDM matrix and the efficient polymer–filler interfacial interactions were constructed. In comparison with EPDM/MS‐II and EPDM/MS‐III, EPDM/MS‐V exhibited outstanding tensile strength, tear strength, elongation at break, and abrasion resistance due to the nanometer particle dimension and good dispersion of MS‐V as well as the stronger interfacial interactions between MS‐V and the EPDM matrix. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Preparation of nano‐zinc oxide/EPDM composites with both good thermal conductivity and mechanical properties

AbstractIn this article, nano‐zinc oxide (ZnO) filled ethylene propylene diene monomer (EPDM) composites are prepared, and the mechanical (static and dynamic) properties and thermal conductivity are investigated respectively, which are further compared with the traditional reinforcing fillers, such as carbon black and nano‐silica. Furthermore, influence of in‐situ modification (mixing operation assisted by silane at high temperature for a certain time) with the silane‐coupling agent Bis‐(3‐thiethoxy silylpropyl)‐tetrasufide (Si69) on the nano‐ZnO filled composites is as well investigated. The results indicate that this novel reinforcing filler nano‐ZnO can not only perform well in reinforcing EPDM but can also improve the thermal conductivity significantly. In‐situ modification with Si69 can enhance the interfacial interaction between nano‐ZnO particles and rubber matrix remarkably, and therefore contribute to the better dispersion of filler. As a result, the mechanical properties and the dynamic heat build‐up of the nano‐ZnO filled composites are improved obviously by in‐situ modification, without influencing the thermal conductivity. In comparison with traditioanl reinforcing fillers, in‐situ modified nano‐ZnO filled composites exhibit the excellent performance in both mechanical (static and dynamic) properties and better thermal conductivity. In general, our work indicates that nano‐ZnO, as the novel thermal conductive reinforcing filler, is suitable to prepare elastomer products serving in dynamic conditions, with the longer expected service life. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Friction and wear behaviour of electron beam modified PTFE filled EPDM compounds

The friction and wear of non-modified and electron beam modified polytetrafluoroethylene (PTFE) filled ethylene–propylene–diene–monomer (EPDM) rubber investigated with the help of pin on disk tribometer showed different behaviour during the sliding contact with hard spherical steel-ball. The friction coefficient ( μ) and specific wear rate ( k) of modified PTFE filled EPDM increased with an absorbed dose of PTFE powder while non-modified PTFE filled EPDM showed the lowest μ and k values. This variation in friction and wear behaviour of PTFE filled EPDM compounds is caused by the influence of radiation induced chemical changes in PTFE powder on the radical initiated peroxide crosslinking. It results from the lower crosslinking efficiency and consequently in the deterioration of the bulk properties. The electron modification of PTFE powder reduces the hardness (modulus) and increases the energy dissipation (tan delta) of compounds. Beside other factors, these variations in bulk properties have been shown to have deleterious effects on the friction and wear properties of electron beam modified PTFE filled EPDM.

Blends of ultrasonically devulcanized and virgin carbon black filled ethylene–propylene–diene monomer rubbers

AbstractUltrasonically devulcanized ethylene–propylene–diene monomer (dEPDM) rubber was blended with virgin ethylene–propylene–diene monomer (vEPDM) rubber. The properties of these blends were investigated and compared with those of blends of ground ethylene–propylene–diene monomer (gEPDM) and vEPDM. The dynamic properties and curing characteristics were studied. The dynamic properties of the uncured blends showed that the gEPDM/vEPDM compounds were more elastic than the dEPDM/vEPDM compounds at a low frequency range, whereas the opposite trend was observed at a high frequency range. In contrast, the dynamic properties of gEPDM/vEPDM vulcanizates were less elastic than those of dEPDM/vEPDM vulcanizates at a low frequency range. The curing characteristics of the blends indicated that an increase in the dEPDM content in the dEPDM/vEPDM blends reduced the scorch time and the maximum torque and increased the minimum torque. A similar but more pronounced tendency was also found for the gEPDM/vEPDM blends. The tensile properties of the dEPDM/vEPDM vulcanizates were much better than those of the gEPDM/vEPDM vulcanizates, indicating the significant benefit of ultrasonic devulcanization. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 132–138, 2004