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The effect of gamma‐irradiation on the ethylene propylene diene monomer (EPDM) based composites, loaded with tungsten and barium sulfate were investigated for radiation resistance properties. The tungsten and barium sulfate fillers were added in different proportion (wt%) to EPDM matrix and prepared using compression molding technique. The developed EPDM composites were exposed to 60Co gamma radiation doses from 0 to 400 kGy. The swelling index of the composites were studied for the irradiated samples and found to decrease with higher gamma doses. Tensile characterization was also carried out and elongation at break, tensile strength and modulus at 100% elongation have been determined for gamma irradiated EPDM based composites. Tensile properties were modified in the irradiated samples and elongation at break is decreased whereas the modulus increases as a function of gamma dose due to increases in crosslinking after irradiation. Thermogravimetric analysis was performed and observed improvement in thermal stability of gamma irradiated EPDM composites. [ABSTRACT FROM AUTHOR]

This study examined the effects of lignin used in EPDM elastomer composites in place of carbon black. For that purpose, lignin was added in amounts of 3.5, 7, and 10.5 phr to investigate the chemical, thermal, rheological, mechanical, and morphological properties of the EPDM elastomers. At the end of the study, tear strength and elongation were enhanced, whereas thermal stability was lowered due to the lignin. The lignin facilitated the vulcanization process and improved the torque values. In the morphology, the lignin was dispersed homogeneously in the matrix, and no voids or cracks were observed except with 10.5 phr. In conclusion, when incorporated at a specified ratio, lignin is economical and provides ecological benefits. Its use as a natural filler can be recommended to automotive industries to provide enhanced properties and ecological properties as a substitute for carbon black. [ABSTRACT FROM AUTHOR]

In this paper Ethylene Propylene Diene Monomer rubber (EPDM) foams were filled with different amounts of paraffin, a common phase change material (PCM) having a melting temperature at about 70 °C, to develop novel rubber foams with thermal energy storage (TES) capabilities. Samples were prepared by melt compounding and hot pressing, and the effects of three foaming methods were investigated. In particular, two series of samples were produced through conventional foaming techniques, involving physical (Micropearl® F82, MP, Lehvoss Italia s.r.l. Saronno, Italia) and chemical (Hostatron® P0168, H, Clariant GmbH, Ahrensburg, Germany) blowing agents, while the salt leaching method was adopted to produce another series of foams. Scanning electron microscopy (SEM) and density measurements showed that MP led to the formation of a closed-cell porosity, while a mixed closed-cell/open-cell morphology was detected for the H foamed samples. On the other hand, foams produced through salt leaching were mainly characterized by an open-cell porosity. The qualitative analysis of paraffin leakage revealed that at 90 °C only the foams produced through salt leaching suffered from significant PCM leakage. Consequently, the thermo-mechanical properties were investigated only in samples produced with H and MP. Differential Scanning Calorimetry (DSC) analysis revealed that EPDM/paraffin foams were endowed by good TES properties, especially at higher PCM contents (up to 145 J/g with a paraffin amount of 60 wt%). Tensile and compressive tests demonstrated the addition of the PCM increased the stiffness at 25 °C, while the opposite effect was observed above the melting temperature of paraffin. These results suggest that the EPDM foams produced with H and MP show an interesting potential for thermal management of electronic devices. [ABSTRACT FROM AUTHOR]

This research aimed to investigate the water vapour transmission properties of chosen EPDM membranes applied in façade and window systems under laboratory tests. The applied procedure included in national and international standards utilized for the laboratory tests of water vapour transmission properties of EPDMmembrane is described. Two main types (outside and inside types) ofEPDMmembranes are laboratory tested. The authors indicated that the EPDM membranes should differ in surface factures. Nevertheless, some manufacturers mark EPDM membranes on each roll (on the package only) without different permanent denotations on the EPDM membranes surfaces. This form of denotations can cause using problems – using the wrong types of the EPDM aprons in building partitions, because when the package is removed there is impossible to visually identify the type of EPDM membrane (outside or inside type) from the texture of the membrane surface. The experimental results of laboratory tests indicated using the wrong type of EPDM membrane in the inside aprons in building partitions in the investigated façade window system. The designed proportion of the sd values (the resistance to movement of water vapour) of inside and out-side EPDM façade membranes should be designed equally to about 3.0 (recommended value 4) to provide proper diffusion properties of partitions around windows in façade systems. The paper can provide scientists, engineers, and designers an experimental basis in the field of the EPDM membranes water vapour transmission properties applied to façades and windows systems.

Reciprocating friction and wear tests of the EPDM are carried out under various loads, and the composition of groups and compounds of EPDM before and after wear is revealed by FTIR and XRD. Then, the stick-slip behavior and wear resistance of EPDM under various loads are analyzed and investigated by real-time curves of the coefficient of friction, friction force, location and the change of friction force. Finally, the wear mechanism of EPDM under various loads is analyzed by the results of SEM. The results show that the stick-slip phenomenon occurs on the EPDM in different degrees under different loads. Neither the wear nor the change in load leads to the formation of new groups and compounds or the decomposition of existing groups and compounds in EPDM. The coefficient of friction does not change monotonically with increasing load, but tends to increase and then decrease. In addition, although the increase in load leads to increases in the lag time and the intensity of noise generated during the wear process, the rate of increase in the lag time and the intensity of noise slows down with increasing load. Meanwhile, with the increase in load, the number of granular debris changes, and banded debris and Schallamach waves become larger, which results in a change in the wear form between the grinding ball and EPDM.

Bottling of aromatised wines and regular table wines often takes place on the same bottling line. Installed sealings in the bottling line absorb volatiles from aromatised wines and, due to inadequate cleaning, carryover occurs into the subsequently bottled regular wine. This unintentional carryover can lead to accusations of illegal flavouring of wine. To minimise the carryover risk, sealing materials that absorb less volatiles are beneficial. Incorporating kaolin and micro-cellulose into the ethylene propylene diene monomer rubber (EPDM) network decreased absorption of the critical α-ionone by 51 and 60 %, respectively. Besides the minimisation of the absorption, a performed cleaning can reduce aroma carryover. So far, knowledge about cleaning parameters that can increase cleaning efficiency is limited since cleaning usually focuses on surficial removal and prevents microbiological cross-contamination. An evaluation of the cleaning parameters, temperature, time and agents clearly revealed a high factor in the considered temperature. The highest cleaning efficiency was seen at 85 °C, whereas the cleaning additives such as citric acid, caustic soda, ozone or dissolved carbon dioxide had no impact. High proportions of the aroma compounds were removed from the polymer in the first 20 min at 85 °C, but none of the performed cleaning sequences was able to remove all compounds.

The mechanical properties of γ-irradiated ethylene propylene diene monomer (EPDM)/high styrene-butadiene rubber (HSBR) blends were investigated with special reference to the effects of blend ratio. Among the blends, the one with 80/20 EPDM/HSBR has been found to exhibit the highest tensile, hardness, thermal, and abrasion properties. The effect of γ-irradiation dose on the mechanical properties namely tensile strength and elongation at break was investigated. The effect of silane coupling agent on the mentioned properties of the EPDM/HSBR blend was studied. The results showed that the mechanical and the thermal properties of the γ-irradiated EPDM/HSBR blend improved with the addition of the silane coupling agent due to the increase in the cross-linking density. The inclusion of both the 30 phr fumed silica and N, N - m -phenylenedimaleimide coagent in the 80/20 EPDM/HSBR nanocomposite irradiated to 150 kGy leads to a synergistic effect. Thermogravimetric analysis was carried out to analyze the thermal stability of the nanocomposites. The mechanical properties have been interpreted in terms of the morphology of the blends as attested by scanning electron microscope. [ABSTRACT FROM AUTHOR]

To prevent the migration of energetic plasticizers in propellants, Graphene oxide (GO) was added as filler to the ethylene propylene diene monomer (EPDM) insulation composite by mechanical mixing. Then, the anti-migration performance was analyzed by investigating the diffusion of dioctyl sebacate using immersion tests at different temperatures. The diffusion coefficient is in the range of 10–14-10–12 m2/s, and the migration activation energy is about 60 kJ/mol. Compared with pure EPDM, the anti-migration effects of EPDM/GO-5 are increased by 15.68%, 9.23%, 8.81%, and 5.69% at 25 °C, 40 °C, 60 °C, and 80 °C, respectively. Moreover, the composite shows a 58% increase in tensile strength and a 132% improvement in the elongation at break by the addition of 5 phr filler of GO. Meanwhile, the thermal stability of the EPDM insulation is also improved with the addition of GO. [ABSTRACT FROM AUTHOR]

In this study, the effects of plastic deformation and failure of the folded part on the folding behavior of non‐crosslinked ethylene propylene diene terpolymer/paraffin oil/silica gel composites were investigated. The folding behavior was evaluated by the residual fold angle of a folded specimen; a lower fold angle indicates an enhanced folding performance. The fold angle decreased with increasing oil and silica content and was correlated with the tensile yield strain, which is generally related to plastic deformation. Furthermore, the test speed dependence of the fold angle for each set of oil contents and test temperatures was investigated. The fold angle decreased with a decrease in the test speed and an increase in the test temperature. Scanning electron microscopy revealed that the low‐fold angle, which indicates an improvement in the folding behavior, was caused by the destruction (voids, crazes, and cracks) of the folded part. [ABSTRACT FROM AUTHOR]

Aramid pulp (AP) is often used as a composite reinforcement due to its excellent properties, but poor dispersion and interfacial adhesion restrict its application in composite materials. In this work, tetraethyl orthosilicate (TEOS) was carried on the surface of AP by supercritical CO2 (scCO2) and hydrolyzed to synthesize the nano‐silica, which improves the dispersion of AP in ethylene‐propylene‐diene elastomer (EPDM). The nano‐silica particles were deposited on the AP surface, and th modified AP was evenly dispersed in the EPDM composites based on the SEM results. Moreover, a silane coupling agent (KH‐560) was brought by scCO2 to further modify the nano‐silica on the surface of the AP to improve the interfacial adhesion. Fourier transform infrared spectroscopy and X‐ray photoelectron spectroscopy results show that after KH‐560 modification, active epoxy groups were introduced on the surface of AP. The tensile strength and tear strength of the KH‐560‐nano‐silica‐AP/EPDM composites were significantly improved, reaching 8.98 and 42.06 MPa, which increased by 26% and 88.10%, respectively, compared with untreated‐AP/EPDM composites. Dynamic mechanical analysis shows that the storage modulus of KH‐560‐nano‐silica‐AP/EPDM composites increased to 2456 MPa compared with the pure EPDM for 1873 MPa, and the loss factor decreased. When the AP was modified in scCO2 with nano‐silica and KH‐560, the composites' oil resistance was also improved. [ABSTRACT FROM AUTHOR]

The present work studies the influence of zinc borate (ZB), magnesium hydroxide (MH) and ammonium polyphosphate (APP) as flame retardants on the curing, mechanical, thermal and flammability performances of Kevlar fibre (KF)-reinforced ethylene propylene diene monomer (EPDM) rubber composites. The flame retardant EPDM/KF composites were prepared with variable ratio of ZB, MH and APP. Thereafter, physicomechanical and thermal properties of the fire retardant EPDM/KF composites were analysed with density analysis, tensile testing, TGA analysis, SEM and cone calorimeter tests. The TGA analysis and cone calorimeter tests showed the enhancement in the flame retardant properties of the EPDM/KF composites with the addition of combined fillers with respect to the virgin counterparts. The synergistic effect of ZB and APP containing flame retardant-incorporated composites exhibited a prominence in the thermal stability and fire retardancy. Heat release rate (HRR) and total heat release rate (THR) of the ZB and APP combined fire retardant-incorporated composites were lower than the virgin EPDM. [ABSTRACT FROM AUTHOR]

The influence of natural antioxidants (rosemary extract, capsaicin, quercetin, or oleanolic acid) in ethylene‐propylene‐diene‐monomer (EPDM) thermal behavior has been investigated by the means of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). EPDM and EPDM/rosemary (RM) composite are investigated with a thermogravimetric (TG) balance in dynamic heating conditions (25°C‐700°C). DSC analysis is also carried out from subambient to better highlight the melting of the polymer and the composite. The obtained DSC and TG values are discussed to have information about the effect of RM content in the polymer stability. [ABSTRACT FROM AUTHOR]

The effect of injection process conditions on the cell structure and mechanical properties of talc and ethylene-propylenediene- monomer (EPDM) filled polypropylene (T-EPDM-PP) composite foams was investigated. Different process conditions such as injection pressure, feedback pressure, injection speed and melting temperature were used. Tensile test and impact test were performed to determine the mechanical properties of the foam materials. In order to compare the mechanical properties, unfomed T-EPDM-PP polymer composite samples were also produced. Obtained experimental data were analyzed using the Taguchi method. The cell morphology of the foams was investigated in terms of skin layer thickness, cell size and cell density using a stereomicroscope, depending on different process conditions. With the increase of injection pressure, injection speed and melting temperature, the tensile and impact strengths of foam samples decreased, while it increased with the increase of the feedback pressure. The tensile and impact strengths of the composite foam increased with the increase in skin layer thickness. Cell size decreased with increasing E.B and EB. High cell density was obtained when low feedback pressure and melting temperature were used together with high injection pressure and injection speed. Foam density decreased with increasing E.B, E.H and E.S. In order to obtain high tensile and impact strength in T-EPDM-PP based composite foam production, optimum process parameters were determined as feedback pressure 100 bar, melting temperature 160 oC, injection speed 60 mm/s and injection pressure 60 bar. [ABSTRACT FROM AUTHOR]

Ethylene-propylene-diene rubbers (EPDM) are one of the most important polyolefin materials widely commercialized and used in various industries in recent years. The production of EPDM is based solely on catalytic coordination polymerization processes. The development of new catalysts and processes for the synthesis of EPDM has expanded the range of products and their manufacturing in terms of energy efficiency, processability, and environmental safety. This mini-review mainly analyzes patented data on the synthesis of EPDM on new-generation single-site catalytic systems based on Group IVB complexes including the systems commercialized by major manufacturers of EPDM. The advantages of these systems are evident in comparison with conventional vanadium systems introduced into production in the 1960s and used to date in the industrial synthesis of EPDM. [ABSTRACT FROM AUTHOR]

In this study, a partially reticulated foam was fabricated based on ethylene propylene diene monomer rubber to absorb low‐frequency acoustic waves. The effect of ethylene content was studied on the cellular structure, viscoelastic behavior, and sound abortion characteristics. High airflow resistivity of the developed partially reticulated structure, as well as highly deformable cell walls of EPDM foams, led to large dissipation of sound energy at low and medium frequencies. Samples with lower ethylene content which exhibited lower storage modulus and larger pore sizes showed higher viscose motions with superior sound absorption. The foam sample with the lowest ethylene content offered the best sound absorption coefficient with a sharp peak as high as 0.91 within the 500–2500 Hz frequency range. The results imply the role of ethylene content as a molecular structure tool to optimize the acoustic absorption potential of EPDM foam. Besides, the foam samples showed considerable insulation performance, yielding a sound reduction index equal to 26–29 dB. The absorption and reflection of the sound waves were integrated to provide the insulation. Thus, a developed lightweight insulator with high resistance to harsh environmental conditions and great low‐frequency sound absorption could be achieved by structural engineering. [ABSTRACT FROM AUTHOR]

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. • A laminated bearing was manufactured using a modified EPDM rubber with excellent anti-peel strength. • The modified EPDM bearings with different shape factors meet the requirements of the specifications. • An empirical model is established to characterise the failure condition of EPDM bearing under ultimate load. [ABSTRACT FROM AUTHOR]

• Developed a wet mixing process to evenly distribute PISF in EPDM. • Optimum overall EPDM/PISF performance is achieved by wet mixing with 10phr PISF. • Wet mixing reduced ΔG′ by 18.08 % and ablation rate by 14.29% vs. dry mixing. • New process improved thermal stability and densified the carbon layer. This research developed a solution wet mixing process for creating Ethylene propylene diene monomer/polyimide staple fiber composites (EPDM/PISF), overcoming the uneven fiber distribution seen in traditional dry mixing techniques. By uniformly dispersing PISF within the EPDM matrix, the wet mixing process improves the composite's performance. This is evidenced by an 18.08 % reduction in ΔG′, a 14.29 % lower linear ablation rate (0.042 mm/s), enhanced thermal stability, a higher charring rate, and a denser carbonized layer. Optimal overall performance was achieved using a PISF content of 10phr in the wet mixing process. This advancement significantly enhances the ablation resistance of EPDM/PIS, making them a promising choice for high-performance and durable insulation in solid rocket motors. [ABSTRACT FROM AUTHOR]

Copyright of Plastics Science & Technology / Suliao Ke-Ji is the property of Plastics Science & Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A series of ethylene-propylene-diene-terpolymer (EPDM)/polyhedral oligomeric silsesquioxane (POSS) composites at different percentage of POSS were prepared and subjected to γ-irradiation. Both irradiated and non-irradiated EPDM and composites were investigated by the means of thermal analysis to verify if the presence of POSS molecules is able to reduce the oxidation level of free radicals generated during the degradation and to evaluate the effects of the irradiation. EPDM composites at 1, 3 and 5 mass% of POSS were thus degraded in a thermogravimetric (TG) balance in dynamic heating conditions (25–700 °C), in both inert and oxidative atmosphere by flowing nitrogen and air respectively. Thermal characterization was then completed by carrying out Differential Scanning Calorimetry (DSC) analysis from sub-ambient to better highlight the melting of the polymer and polymer composites occurring just above the room temperature. FTIR spectroscopy was also performed for the prepared samples to check the presence of the molecular filler in the composites and for the TG's residue at 700 °C, in order to evaluate its nature. DSC and TGA parameters were detected and discussed to have information about the effect of the degradation's environment, the effect of irradiation on polymer stabilization and the effect of POSS content in the polymer matrix. [ABSTRACT FROM AUTHOR]

It is of a great challenge to apply nonmetal fractions (NMFs) of waste printed circuit boards (WPCBs) as reinforcing fillers in rubbers. In this paper, a typical amorphous synthetic rubber, ethylene propylene terpolymer (EPDM), is used as the model material to investigate the mechanical properties of EPDM/NMFs composites. A multifunctional grafting monomer containing two thiol groups and two carboxyl groups is designed and synthesized. The monomer is used to synthesize highly grafted EPDM-g-AA via melt grafting. Tensile strength of EPDM/NMFs composite sharply increases to 18 MPa when 10phr of EPDM-g-AA is used. The grafted polymer also significantly improves the thermal oxidation resistance. It can be expected that the strategy is able to be expanded to other rubber systems and opens the door to application of NMFs in rubber industry. [ABSTRACT FROM AUTHOR]

A new antioxidant was prepared by graft copolymerization of N (4‐phenylenediamine) maleimide (pPDAM) onto natural rubber (NR). Fourier transform infrared technique was used to confirm the grafting of (pPDAM) onto the NR backbone. The grafted copolymer (NR‐g‐pPDAM) was incorporated into the ethylene propylene diene monomer rubber (EPDM) rubber mix as an antioxidant. For comparison purposes, a widely used antioxidant N‐(1,3‐dimethylbutyl)‐N′‐phenyl‐p‐phenylenediamine (6PPD) was used in addition to a blank sample without antioxidant. The rheometric characteristics of EPDM vulcanizates were determined using an oscillating disc rheometer. Different mechanical properties of the EPDM vulcanizates were measured before and after exposure to thermal and ultraviolet/ozone (UV/O3) accelerated aging. The results revealed that the grafted antioxidant NR‐g‐pPDAM is more efficient, for EPDM rubber vulcanizates than the commercial antioxidant (6PPD). EPDM containing grafted (NR‐g‐pPDAM) antioxidant exhibited promising properties, such that it is expected to fulfill major requirements of industrial, automotive, and construction applications. [ABSTRACT FROM AUTHOR]

High-pressure storage and cyclic (de)pressurization of hydrogen gas is known to result in degradation and failure of gas canisters, hoses, linings, and O-rings as the relatively small hydrogen molecule can readily permeate most materials. Hence, identifying material compositions that are less susceptible to hydrogen-induced damage is of significant importance to the hydrogen energy infrastructure. Here, we use classical atomistic molecular dynamics simulations to study hydrogen exposed ethylene-propylene-diene monomer (EPDM) rubber, an elastomer typically used in O-rings. We make chemical modifications to the model by adjusting the crosslink density and report on gas solubility, diffusivity, and molecular restructuring in response to rapid decompression. Our simulations indicate that increases in crosslink density can reduce volumetric expansion during decompression and result in smaller free volume pore sizes. However, these favorable properties for sealing materials come with a tradeoff. At pressure, crosslinks introduce extra free volume, providing potential sites for gas localization, the precursor to cavitation-induced failure. • MD simulations of EPDM compare H 2 (de)pressurized states at the molecular level. • Increases in crosslink density reduce volumetric expansion following decompression. • Increases in crosslink density result in smaller free volume pore sizes. • Crosslinks introduce extra free volume at pressure. [ABSTRACT FROM AUTHOR]

Ethylene–propylene–diene monomer (EPDM) composites were usually enhanced with ablative additives to protect solid rocket motor (SRMs) casings. However, the poor thermal insulation caused by the high thermal conductive ablative fillers can lead to rocket motor failure. Herein, the novel EPDM composites containing alternating layers of ablative EPDM (AM) and heat-insulated EPDM (HM) were prepared through layer-multiplying extrusion. Compared with conventional EPDM ablative material, the multilayer composites showed enhanced thermal insulation and mechanical properties that could be further improved by tuning the number of layers. The ablation and thermal insulation properties possessing in AM and HM layers could be combined by forced assembly during co-extrusion, and the alternating multilayer composite was capable of showing the effect of each component. In particular, compared with AM, the maximum back-face temperature with 40 alternating layers of AM/HM decreased from 96.2 °C to 75.6 °C during oxyacetylene test, while the good ablation properties were preserved in the AM component. This significant improvement was attributed to the planar orientation and densification of ablative additives, and the interruption of conductive pathways in the through-plane direction of AM/HM alternating laminate. The anisotropic EPDM composites featuring mechanical robustness, good ablative resistance and thermal insulation suggest considerable potential application in the aerospace industry. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

With the increasing interest in hydrogen energy, the stability of hydrogen storage facilities and components is emphasized. In this study, we analyzed the effect of high-pressure hydrogen gas treatment in silica-filled EPDM composites with different silica contents. In detail, cure characteristics, crosslink density, mechanical properties, and hydrogen permeation properties were investigated. Results showed that material volume, remaining hydrogen content, and mechanical properties were changed after 96.3 MPa hydrogen gas exposure. With an increase in the silica content, the crosslink density and mechanical properties increased, but hydrogen permeability was decreased. After treatment, high-silica-content composites showed lower volume change than low-silica-content composites. The crack damage due to the decompression caused a decrease in mechanical properties, but high silica content can inhibit the reduction in mechanical properties. In particular, EPDM/silica composites with a silica content of above 60 phr exhibited excellent resistance to hydrogen gas, as no change in their physical and mechanical properties was observed. [ABSTRACT FROM AUTHOR]

Rubber-based insulation materials have been widely used in the field of electrical engineering. To develop rubber with excellent nonlinear electrical conductivity can relieve the electric field concentration in the stress cone of a cable accessory. In this study, ethylene propylene diene monomer (EPDM) was selected as the rubber matrix, and copper nanoparticles (CuNPs) were grown on hexagonal boron nitride (BN) using a liquid-phase chemical reduction method. The prepared CuNPs/BN fillers were introduced into the EPDM matrix to obtain CuNPs/BN/EPDM composites. The microstructures of fillers and composites were systematically characterized. Specifically, the electrical conductivity and breakdown field strength at different temperatures were measured and analyzed. The results show that filling CuNPs/BN enables the EPDM to have outstanding nonlinear electrical conductivity and weakens the temperature dependence of the electric breakdown strength. The simulation analyses also prove that CuNPs/BN/EPDM composites with nonlinear conductivity can avoid the electric field concentration in the stress cone, which is beneficial to ensure the safety and reliability operation of a cable accessory. [ABSTRACT FROM AUTHOR]

This study, uses two polyfunctional monomers (PFMs) namely ethylene glycol dimethacrylate (EGDMA) as a bifunctional monomer and trimethylolpropane triacrylate (TMPTA) as a trifunctional monomer were used as co-agents in irradiation crosslinking of Ethylene Propylene Diene Monomer Rubber (EPDM). The effect of concentration of each PFM and irradiation dose on the crosslinking density, gel content, swelling behavior in motor and brake oils, in addition to the mechanical and thermal stability properties of EPDM was investigated in detailed. The results showed a remarkable increase in the gel content, crosslinking density and mechanical properties as the concentration of PFMs increased from 1 to 5 phr (parts per hundred parts of rubber). The various blends of EPDM with the trifunctional monomer express the highest gel content and crosslinking density than those with the bifunctional monomer. The addition of 5 phr of TMPTA to EPDM causes a dramatic improvement in tensile strength (TS) of the prepared blend reached to 188% compared to neat EPDM at 50 kGy. At the same time, the maximum TS of the blend containing 5 phr of EGDMA achieved only 41% compared to neat EPDM at an irradiation dose of 100 kGy. The swelling of irradiated samples in brake oil revealed a stronger oil resistance than motor oil. For all irradiated samples, the oil uptake decreased with the irradiation dose up to 100 kGy. The EPDM samples containing 5 phr of TMPTA recorded the highest oil resistance at 100 kGy. The results also showed that the addition of PFMs and irradiation treatment of the various prepared blends improved the thermal stability of EPDM. Finally, neat EPDM and the blends containing 1 and 3 phr of EGDMA can be used as radiation dosimeters in the very high dose range (50–200 kGy). [ABSTRACT FROM AUTHOR]

High oleic soybean oil and hydrogenated soybean oils having a different degree of unsaturation were investigated as bio‐based plasticizers for ethylene‐propylene‐diene monomer (EPDM) rubber filled with carbon black and vulcanized with sulfur. The plasticizing effect of the oils with different unsaturation levels was studied by dynamic mechanical analysis (DMA) while the variation in crosslink density of EPDM rubbers was investigated by the equilibrium solvent swelling method. The linear thermal expansion coefficient (LTEC) at different temperatures for EPDM rubbers formulated with different oils was examined by thermomechanical analysis (TMA). The oil with the highest level of unsaturation demonstrates the greatest plasticizing effect but interacts with vulcanizing sulfur lowering crosslink density and deteriorating the mechanical properties of the EPDM rubber. Hydrogenated oil with all‐saturated fatty acid chains shows no decrease in crosslink density, improvements in the mechanical properties of rubber but is less effective as a plasticizer for EPDM. The results of tensile testing for EPDM rubbers formulated with different concentrations of soy‐based oils were studied, correlated, and discussed. The properties of soy‐based EPDM rubbers compared to the properties of EPDM rubbers formulated with petroleum‐based paraffinic oil. [ABSTRACT FROM AUTHOR]

Bifunctional reactive polyhedral oligomeric silsesquioxane (POSS) of 3, 13‐divinyl octyphenyl silsesquioxane (DV‐DDSQ) and 3, 13‐dihydro octyphenyl silsesquioxane (DH‐DDSQ) were used as additive to modify ethylene‐propylene‐diene rubber (EPDM), and double vinyl groups or active hydrogen groups of bifunctional reactive POSS (brPOSS) underwent a cross‐linking reaction with the active hydrogen groups and double bonds of EPDM, to investigate the effect of brPOSS regulating functional reaction group on the properties of EPDM. Crosslinking density, mechanical properties, thermal stability and ablation performance of brPOSS modified EPDM were investigated, and the pyrolysis behavior and surface structure of modified EPDM was analyzed by X‐ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Furthermore, the ablation performance of brPOSS modified insulation based on EPDM was investigated. The results showed that the tensile strength of EPDM/DV‐DDSQ and EPDM/DH‐DDSQ increased by 35.8% and 55.3% respectively compared with EPDM; the tear strength increased by 6.4% and 5% than that of EPDM. Moreover, the 5% initial thermal decomposition temperature based on thermogravimetric analysis (TGA) and mass (or linear) ablation rate ablative performance of brPOSS modified EPDM were optimized to a certain extent, and the ablative performance of brPOSS modified insulation based on is significantly improved, the mass ablation rate of DV‐DDSQ/insulation and DH‐DDSQ/insulation decreased by 35.4% and 41.6% respectively, and linear ablation rate decreased by 38.2% and 39.4% respectively. [ABSTRACT FROM AUTHOR]

In this paper, ecological-friendly materials based on ethylene–propylene–diene terpolymer (EPDM) with improved thermal and radiation stabilities by Chlorella vulgaris (CV) and Spirulina platensis (SP) powders were investigated by complementary procedures: FTIR spectroscopy and isothermal and nonisothermal chemiluminescence (CL). The stabilization potential of microalgae was evaluated at several degrees of γ-radiolysis by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay, while the polymer resistances were studied on a large range of algal concentrations (1, 3, 5 and 10 mass%). The carbonyl and hydroxyl indices of all degraded EPDM formulations were found to be two times smaller in the presence of algal powders, if compared to the pristine material. Some dissimilarities between the oxidation development in pristine and modified EPDM appeared, especially in unirradiated samples. The activation energies required for the oxidation of EPDM and the lifetime of these samples at various temperatures between room temperature and 100 °C were calculated. The antioxidant compounds existing in the studied microalgae proved a significant influence on the stability of EPDM, mainly in the presence of SP, which was confirmed by the activation energies calculated from our CL results. The investigation of cycling thermal degradation revealed the obvious contribution of additives towards delaying EPDM ageing. [ABSTRACT FROM AUTHOR]

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This review addresses a comparison, based on the literature, among nitrile rubber (NBR), ethylene-propylene-diene-monomer rubber (EPDM), and polyurethane (PU) elastomeric heat shielding materials (EHSM). Currently, these are utilized for the insulation of rocket engines to prevent catastrophic breakdown if combustion gases from propellant reaches the motor case. The objective of this review is to evaluate the performance of PU–EHSM, NBR–EHSM, and EPDM–EHSM as insulators, the latter being the current state of the art in solid rocket motor (SRM) internal insulation. From our review, PU–EHSM emerged as an alternative to EPDM–EHSM because of their easier processability and compatibility with composite propellant. With the appropriate reinforcement and concentration in the rubber, they could replace EPDM in certain applications such as rocket motors filled with composite propellant. A critical assessment and future trends are included. Rubber composites novelties as EHSM employs specialty fillers, such as carbon nanotubes, graphene, polyhedral oligosilsesquioxane (POSS), nanofibers, nanoparticles, and high-performance engineering polymers such as polyetherimide and polyphosphazenes.

Acrylonitrile‐butadiene rubber (NBR) and ethylene‐propylene‐diene monomer (EPDM) gaskets are used as seals in plates heat exchangers due to their elasticity and resilience. However, contact with fluids, oxygen, ozone, and heat lead to permanent deformation. This study investigates the degradation of gaskets submitted to similar service conditions: compressed in a groove for up to 360 h at 100 and 120°C. The analysis was carried through compression set (CS), compression stress relaxation, surface morphology, Shore A hardness, indentation modulus profile, crosslink density, and Fourier transform infrared region with attenuated total reflection analysis. For EPDM, in thermo‐oxidative aging there is a counterbalance between chain scission and crosslinking, which increases CS while hardness and crosslink density remain low. For NBR, diffusion‐limited oxidation causes heterogeneous oxidation, creating a crosslinking network near the surface. The values for CS, Shore A hardness, and crosslink density raised to 50%, 10%, and 75%, respectively. Furthermore, the side thermo‐oxidation was reduced due to the presence of the groove, which reduces oxygen access. Using FITR analysis, a thermo‐oxidative interaction mechanism was proposed for the EPDM and NBR gaskets. It was concluded that EPDM presented a more reliable behavior for the gasket and seal applications under the analyzed conditions. [ABSTRACT FROM AUTHOR]

To overcome the low modulus and low maximum service temperature of polypropylene (PP) and ethylene-propylene-diene monomer (EPDM) blends, incorporation of talc into blend have been considered. In this study, the effect of various mixing methods of morphological behavior and mechanical properties of PP/EPDM/talc compound were investigated. Samples were prepared by different methods in internal mixer and co-rotating twin-screw extruder. It was found, the tensile properties were not affected by applying different mixing methods.The highest impact resistance was related to sample which had pre-blending on two roll mills and finally mixed in the internal mixer. Scanning electron microscopy (SEM) micrographs showed that the rubber dispersed morphology for all samples and the finest morphology was related to sample with the highest impact resistance. Because of pre-blending of EPDM/talc on two roll mills, this sample showed the best dispersion and distribution of talc. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This paper investigates the tracking and erosion of silicone rubber and EPDM insulation in the DC inclined plane tracking and erosion test. Silicone rubber filled with alumina tri-hydrate fails due to combustion in the gas phase or erosion paths, but with no evidence of tracking. EPDM fails due to tracking and surface capturing fire, from dry-band arcing leaving a black residue while impinging the surface. Carbonaceous residue on EPDM gives rise to leakage current magnitude, whereas fused silica-based residue on silicone rubber is shown to promote combustion. A high amount of alumina tri-hydrate replacing the polymeric fuel in the composite is shown as a primary factor preventing failure and changing the nature of the residue in the DC inclined plane tracking and erosion test. Depolymerization is the main degradation mechanism reported for silicone rubber and EPDM, with notable degrees of crosslinking reported only for silicone rubber. Crosslinking reduces the amount of silicone rubber undergoing depolymerization, thus, the amount of fuel prone to combustion is reported to promote a coherent residue shield against the eroding dry-band arcing. [ABSTRACT FROM AUTHOR]

Polymeric insulators have lightweight, excellent hydrophobicity and convenient transportation and installation. They are widely used in the external insulation for distribution and transmission lines. However, due to the long-term effects of pollution, ultraviolet radiation, discharge, temperature, humidity, altitude and other natural and complex environmental and service factors, the silicone rubber and other materials of polymeric insulators gradually age and lose their hydrophobicity and electrical insulation characteristics. The operability is significantly reduced, which seriously affects the safety and reliability of the power system. Hence, there is a need for assessing and evaluating the long-term aging and degradation of polymeric insulators under various operating conditions and environments. In this review, the various aging and characterization techniques of the polymeric insulators and their aging performance under the action of multiple factors are discussed. To enhance the performance of polymeric insulators, nano-coating, surface treatment and other techniques are also indicated. In addition, future potential fields that should be explored from a high-voltage electrical insulation perspective are also presented.

In order to study the failure reason of the soft PSD in the dual pulse solid rocket motor (SRM), the deformation process of the intermediate section of the second pulse combustion chamber was simplified to the two-dimensional plane strain state, and the calculation method of the circumferential strain of the soft PSD was obtained. The influencing factors of the circumferential strain of the soft PSD were studied. The main factors affecting the circumferential strain of the soft PSD are the gap between the soft PSD and the propellant grain, and the circumferential strain on the inner surface of the propellant grain. The calculation method could be used to initially estimate the circumferential strain of the soft PSD, and then predict the rationality and feasibility of the design scheme. The apparent morphology and area change rate of EPDM materials of PSD under different strains were studied by DIC tensile test. The variation of the porosity of the EPDM material with the increase of strain was obtained by micro-CT. By comparing the SEM results of the fracture and the slit of the tensile test piece, the failure mode of the EPDM material of PSDs was determined, and the failure mechanism of the PSD structure was obtained. The conclusions obtained in this paper can provide a useful reference for the design of the PSD in dual pulse SRM. [ABSTRACT FROM AUTHOR]

The third monomer is an important characteristic of EPDM rubber, as it directly influences the mechanical and thermal properties of the material. Peroxide vulcanization is often used as a curing system. Furthermore, it increases lifetime and offers dynamic mechanical properties and scorch time lower than sulfur systems. Here, we report the influence of dipentamethylene thiuram tetrasulfide and HVA-2 (N,N-m-phenylene bismaleimide) on peroxide vulcanization at different ENB content on EPDM rubber to reach an ideal condition for the reduction of vulcanization scorch time and improve the its mechanical properties. Tensile strength was highly affected by SDS formulation, increasing to 10 MPa for ENB1.8% and 15 MPa for ENB4.9% and ENB8.5%. Moreover, elongation at break increased from 398 to 650% for ENB1.8%, from 260 to 433% for ENB4.9% and from 290 to 408% for ENB8.5%. Compression set of SDS system was also increased when different ENB contents were compared for a conventional vulcanization system. Tear strength of ENB4.9% and 8.5% enhanced from 25 to around 32 N/mm with the scorch delay system. These results are important for the improvement of gaskets of plate heat exchanger production. [ABSTRACT FROM AUTHOR]

This paper presents a characterization of PA6 and the blend PA6+EPDM (60/40) by tensile tests in order to evaluate several mechanical properties for impact resistance applications. Results were found to be dependend on test rate (10 mm/min, 250 mm/min and 1000 mm/mm). SEM investigation point out a homogenous structure. The blend has better value of energy at break, for the higher test speed: for v=250 mm/min this characteristic has the value of energy at break 29.7 J and the blend has 76.3 J. At 1000 mm/min, PA6 has this charcateristic of 20 J, but for the blend, it is almost insensitive for the two higher test speeds (76.3 J at 250 mm/min and 72.4 J at 1000 mm/min, respectively) as compared to the neat polymer that decreases this feature when thr test spee increases. At the lowest teste speed, the values of energy at break for the materials in this study are close (90.2 J for PA6 and 87.7 J for the blend). The results from tensile tests pointed out that the formulated blend is recommended for impact resistance applications. [ABSTRACT FROM AUTHOR]

Two potential formulations of sulfur cured ethylene propylene diene terpolymer (EPDM) insulation were characterized against the proven insulation based on nitrile rubber (NBR) in the earlier study. Unlike the proven insulation, the cure behavior exhibited by sulfur cured EPDM is quite different in that, the rheometer curves exhibit marching behavior even at elevated temperature for longer duration (160°C for 7 h; most severe condition). This warranted extensive cure study at different temperatures for varying durations in order to determine the optimum cure condition. The methodology adopted to find out the optimum cure condition and corroboration of the same in terms of instrumental techniques (differential scanning calorimetry, thermogravimetric analysis, and Fourier transform infrared), which are quite interesting, are discussed in this article. [ABSTRACT FROM AUTHOR]

Equilibrium 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. [ABSTRACT FROM AUTHOR]