Ethylene Propylene Diene Monomer Samples Research Articles

Investigation of novel polyanilines as new antioxidants for ethylene propylene diene monomer rubber composites

AbstractOxidative aging is a significant deterioration process that affects the performance and durability of rubber materials in various applications. Therefore, this study focuses on the development of new antioxidants‐based on polyaniline for ethylene propylene diene monomer (EPDM) rubber to enhance its resistance to oxidative aging. The novel polyanilines were prepared using in situ polymerization method and characterized using Fourier transforms infrared (FTIR) and thermogravimetric analysis (TGA). FTIR illustrates the success synthesis of polyanilines as it shows their characteristic functional groups. The thermal stability of the formed polyanilines is discussed through TGA and derivative of thermogravimetry (DTG) curves. The curves prove the good thermal stability of the synthesized polymers. The prepared polyaniline compounds were mixed to carbon black filled‐EPDM rubber composites using a roll mill and then vulcanized using sulfur curing process. Accelerated aging tests for the prepared EPDM rubber composites were conducted to evaluate the effectiveness of the antioxidants. Moreover, their impact on rheometer, mechanical, and swelling properties was studied. The results showed that the EPDM samples with the prepared polyaniline compounds exhibited improved oxidative properties compared to the EPDM sample with commercial antioxidant 2,2,4‐trimethyl‐1,2‐dihydroquinoline. These findings suggest that the novel antioxidants have the potential to enhance the durability and performance of EPDM rubber in various applications.

An effective way to control the radical reaction and its mechanism in EPDM under γ-ray irradiation

The effects of a compound that contains a xanthate group named DIP on the radical reactions and structural evolution of the ethylene propylene diene monomer (EPDM) were investigated. It was found that the structural evolution and long-term stability of the EPDM can be realized by controlling the radical reaction in the matrixes of EPDM during γ-ray irradiation. The results show that the DIP can prevent EPDM deterioration, when the γ-ray irradiation dose reaches 450 kGy, the retention rate of the elongation at break and tensile strength of the EPDM samples containing 1 wt% DIP could remain about 90% and 160%, while those of additive-free EPDM are only about 33% and 70%. On the other hand, the thermal stability of the EPDM samples decreases markedly with the dose increasing under γ-ray irradiation. However, the thermal decomposition temperature of the EPDM samples containing DIP remains basically unchanged after irradiation, and DIP can also improve the oxidation resistance of the EPDM. Electron spin resonance studies reveal that DIP can effectively control the radical reactions inside the EPDM during γ-ray irradiation. Rheology results show that the structural evolution of the EPDM can be well controlled under γ-ray irradiation owing to the presence of DIP in the EPDM matrixes. Density functional theory calculations indicate that the reversible radical reactions inside EPDM/DIP systems are crucial in realizing the long-term stability and controllable structural evolution of the EPDM under γ-ray irradiation.

Mechanism Characterization and Nondestructive Inspection Method of Thermal Degradation Faults in EPDM Cable Termination

There is a significant positive proportional correlation between the condition of ethylene propylene diene monomer (EPDM) insulation and partial discharge(PD) characteristics in electric multiple units (EMU) cable termination. Especially for the cable terminations with long service life, the aging effect of EPDM insulation material is significant due to long-term high-current load. In this paper, electrical deterioration and PD development of EPDM insulation under long-term thermal degradation is conducted. During the test process, the phase-resolved partial discharge (PRPD) analysis, partial discharge inception voltage (PDIV), physicochemical properties, and flashover voltage of EPDM samples with different thermal degradation are measured. The relationship between the thermal degradation extent of EPDM insulation and PD characteristics is also proposed. The results show that electrical deterioration of the aged sample can be divided into four gradations by PD amplitude and pulse repetition rate. In the four gradations, the shape of the PRPD spectrum in every gradation changes significantly with different thermal degradations. Surface morphologies of EPDM insulation show different features such as gully areas and white particles. The results of the Fourier transform infrared spectroscopy(FTIR) test indicate that the increase of oxygen-containing groups and free radicals are the key reasons for the rapid PD development process of cable insulation under different electrical gradations and thermal-oxygen degradations.

The investigation of effects of environmental conditions on fatigue strength and spring stiffness of rubber materials

Rubber materials are widely used in many applications. The most important applications of rubber materials are seals, tires, gaskets, hoses, hydraulic-pneumatic systems and vibration absorbers. Today, the working environment of rubbers varies. It has become important to see the responses of developed rubber materials to these challenging working conditions. Most rubber parts are subjected to fluctuating loads that can cause fatigue damage in their work environments. In this study, fatigue strength and spring stiffness of rubber materials under different environmental conditions is investigated. Three general factors that affect fatigue strength of rubber materials are the effects of mechanical loading, environmental effects and the effects of rubber formulation. In this study these factors are examined. For this purpose, fatigue strength and spring stiffness of natural rubber (NR), specially developed natural rubber (S-NR) and ethylene propylene diene monomer (EPDM) rubber were examined. The fatigue tests of rubber samples were performed before and after aging processes. During the study, the static and dynamic stiffness values of the rubber materials were examined before and after aging processes. As a result of experimental study, it was found that fatigue life decreases as a result of accelerated aging and annealing in heated oil processes for NR, EPDM and S-NR samples. Annealing in heated oil process is more effective in reducing fatigue life of rubber samples compared to accelerated aging. In this study, it is seen that S-NR rubber has the highest fatigue strength among rubber materials tested. It has been determined that production of samples with the semi-active vulcanization system is the most important parameter in increasing fatigue strength. In S-NR samples produced with the semi-active vulcanization system, the loss in spring stiffness occurring under different aging conditions is less compared to the loss in spring stiffness in conventional vulcanization system produced NR and EPDM samples.

Research on property variation of silicone rubber and EPDM rubber under interfacial multi-stresses

In this paper, silicone rubber (SR) and ethylene propylene-diene monomer (EPDM) rubber used in 110 kV prefabricated joints of XLPE cables were chosen as subjects, and a multi-stress experimental device was set up to simulate the insulation interface. Different mechanical tensions and/or AC electrical stresses were applied to the rubber samples at the interface composed of XLPE and SR/EPDM. After preset times, microscopic observations, together with measurements of mechanical properties, volume resistivity, crosslinking degree, attenuated total reflectance Fourier infrared spectrum and X-ray photoelectron spectroscopy were performed. It is shown that for both materials, molecular chains are partly broken by electron or ion bombardment from the discharges under electrical stress, and micro-molecules and oxides are formed on the sample surfaces. The mechanical stress facilitates this process without changing the reaction essence. The volume characteristic parameters of SR samples degraded with aging, while those of EPDM samples remained relatively stable. It is shown that under the same interfacial electrical-mechanical stresses, SR samples shows degradation of the overall performance; while for EPDM samples, the damage occurs mainly on the surface. This is due to the different chain structures, filler types and content in the materials.

Supervision of Ethylene Propylene Diene M-Class (EPDM) Rubber Vulcanization and Recovery Processes Using Attenuated Total Reflection Fourier Transform Infrared (ATR FT-IR) Spectroscopy and Multivariate Analysis.

Ethylene propylene diene monomer (EPDM) rubber is widely used in a diverse type of applications, such as the automotive, industrial and construction sectors among others. Due to its appealing features, the consumption of vulcanized EPDM rubber is growing significantly. However, environmental issues are forcing the application of devulcanization processes to facilitate recovery, which has led rubber manufacturers to implement strict quality controls. Consequently, it is important to develop methods for supervising the vulcanizing and recovery processes of such products. This paper deals with the supervision process of EPDM compounds by means of Fourier transform mid-infrared (FT-IR) spectroscopy and suitable multivariate statistical methods. An expedited and nondestructive classification approach was applied to a sufficient number of EPDM samples with different applied processes, that is, with and without application of vulcanizing agents, vulcanized samples, and microwave treated samples. First the FT-IR spectra of the samples is acquired and next it is processed by applying suitable feature extraction methods, i.e., principal component analysis and canonical variate analysis to obtain the latent variables to be used for classifying test EPDM samples. Finally, the k nearest neighbor algorithm was used in the classification stage. Experimental results prove the accuracy of the proposed method and the potential of FT-IR spectroscopy in this area, since the classification accuracy can be as high as 100%.

The study of temperature and radiation induced degradation of cable polymers: A comparison between the mechanical properties of industrial and neat EPDM

The mechanical properties of industrial and neat Ethylene Propylene Diene Monomer (EPDM) polymers, aged under γ-irradiation at different temperatures, are studied. The focus is given to the dose rate effects in polymer insulation materials, so the ageing is performed in the wide range of dose rates, doses and temperatures. Industrial EPDM samples are extracted from the cables in use in Belgian Nuclear Power Plants (NPP), and the neat EPDM samples are produced in the laboratory. The mechanical tests of non-aged and aged polymers are performed, and the methodology of estimating the polymer life time is discussed. The ultimate tensile stress and elongation at break are found to be strongly affected by both irradiation condition and temperature. The ultimate tensile stress clearly exhibits the dose rate effect observed through the shift of the crossover between cross-linking to chain scission process as a function of the dose. This crossover shifts to high dose for large dose rates, while the opposite is observed by increasing the temperature. Dose rate effect is less evident in the elongation at break data, probably because both cross-linking and chain scission affect the elongation at break in the same way, by decreasing it. In comparison to industrial EPDM aged under the same conditions, the cross-linking to chain scission crossover appears at lower dose in neat polymer and the elongation at break decreases faster by increasing the dose. In addition, the elongation at break experimental results can be modeled by changing single parameter, namely pre-exponential factor of the irradiation rate constant. This confirms that both aging processes, cross-linking and chain scission affect the elongation at break in a similar way, by deteriorating network structure responsible for polymer elastic properties. Irradiation rate constant is found to follow the square root dependence for industrial EPDM, while the linear dependence is observed for the neat EPDM. This indicates the existence of different degradation processes in these two polymers.

Enhanced thermo-oxidative aging resistance of EPDM at high temperature by using synergistic antioxidants

In this work, zinc dimethacrylate (ZDMA) and 2-sulfur-benzimidazole (MB)/N-4(phenyl–phenyl)-maleimide (MC) were simultaneously used as synergistic antioxidants to improve the thermo-oxidative aging resistance of peroxide vulcanized ethylene-propylene-diene monomer (EPDM) for its application at high temperature. For comparison purpose, the control sample without antioxidants, the traditional antioxidant package, the combined antioxidant MB/MC, and pure ZDMA were also investigated. The results showed that the crosslinking density of EPDM was only slightly decreased before aging by using the combined antioxidant MB/MC/ZDMA, and the increase in crosslinking density was much less than other antioxidants at the same aging time, indicating the largely improved aging resistance of EPDM. As a result, the change in mechanical properties was the lowest for EPDM with the combined antioxidant MB/MC/ZDMA at high temperature. Meanwhile, the results from structure analysis showed that the degree of oxidation of EPDM was much lower than other systems after aging at 180 °C for 216 h by using the combined antioxidant MB/MC/ZDMA. In addition, the surfaces of EPDM samples with MB/MC/ZDMA as synergistic antioxidants or the combined antioxidant MB/MC were still smooth after aging at 180 °C for 216 h, whereas severe cracks occurred for other antioxidative systems. These results suggest the good thermo-oxidative aging resistance of the synergistic antioxidant MB/MC/ZDMA. Finally, the synergistic antioxidative mechanism of MB/MC/ZDMA was carefully discussed.

Mechanical and physicochemical properties of electron beam irradiated rubber/clay nanocomposites

Effect of electron beam irradiation on the mechanical and physicochemical properties of both styrene butadiene rubber (SBR)/clay and ethylene propylene diene monomer (EPDM)/clay nanocomposites containing clay contents from 3 to 10 phr prepared by melt blending method has been investigated. The prepared composites were subjected to electron beam irradiation doses of up to 150 kGy to induce radiation curing, whereas the mechanical properties in terms of tensile strength (TS), tear strength (Ts), and elongation at break (Eb) were studied as a function of irradiation dose and clay content. TS and Ts increased with increasing irradiation dose up to 100 kGy, they were decreased with further increase in dose. An increase in TS and Ts for SBR and EPDM nanocomposites containing various organomodified montmorillonite (OMMT) contents (3–5 phr) was noticed, whereas a decrement behavior was observed at higher OMMT content. The elongation at break decreased continuously with both irradiation dose and OMMT content. The crosslink density for either EPDM or SBR samples increases with increasing irradiation dose up to 150 kGy and by increasing clay content up to 5 phr, whereas it decreases at higher clay content (7–10 phr). At 5 phr OMMT and 100 kGy irradiation, SBR nanocomposites showed higher TS and Ts than EPDM nanocomposites, while the crosslink density of SBR is lower. POLYM. COMPOS., 34:1600–1610, 2013. © 2013 Society of Plastics Engineers

Enhancement of the properties of EPDM/NBR elastomers using nanoclay for seal applications

AbstractIn this research, we have investigated the effects of addition of different percentages of nanoclay to the ethylene propylene diene monomer (EPDM) and nitrile butadiene rubber (NBR) on the characteristics of these rubbers as seal material. Properties such as tensile strength, modulus at different extensions, elongation at break, compressive set, hardness, and permeability and abrasion resistance are tested to assess the effect of addition of the nanoclay. Results indicate that addition of nanoclay at certain compositions could slightly reduce the strength of the rubber. However more stable modulus at different strains are provided, the hardness of the rubber is preserved and slightly enhanced, the permeability is reduced in both rubbers especially considerable decrease in EPDM is observed which is desirable in diminishing the effect of explosive decompression. At the same time the compression test shows that the nanoclay improves the performance of the rubbers under compression which is essential in seal application. The X‐ray diffraction tests clarify that the dispersion of the nanoclay in the NBR samples is of high quality. In the EPDM samples, the dispersion is in need of improvement. POLYM. COMPOS., 2009. © 2009 Society of Plastics Engineers

Surface improvement of EPDM rubber by plasma treatment

The surface of ethylene-propylene-diene monomer (EPDM) rubber was treated in N2/Ar and N2/H2/Ar RF plasmas in order to achieve similar or better adhesion properties than NBR (acrylonitrile-butadiene) rubber, nowadays used as thermal protection of rocket chambers. The surface properties were studied by contact angle measurements and by x-ray photoelectron spectroscopy (XPS). The treated surfaces of the EPDM samples show a significant reduction in the contact angle measurement, indicating an increase in the surface energy. XPS analyses show the incorporation of polar nitrogen- and oxygen-containing groups on the rubber surface. After plasma treatment the presence of oxygen is observed due to surface oxidation which occurs when the samples are exposed to the air. Atomic force microscopy and scanning electron microscopy analyses indicate a decrease in the EPDM rubber surface roughness, promoted by surface etching during the plasma treatment. Strength tests indicate improvement of about 30% and 110% in the adhesion strength for the plasma treated EPDM/polyurethane liner interface and for the EPDM/epoxy adhesive interface, respectively. The adhesion strength of the EPDM/liner is similar to that obtained for the NBR/liner, which indicates that EPDM rubber can safely be used as thermal protection of the solid propellant rocket chamber.

Calibration of cyclohexane solid–solid phase transition thermoporosimetry and application to the study of crosslinking of elastomers upon aging

Photo-aging of elastomers results in two competitive processes: chain- scissions and crosslinking. The solid-to-solid cyclohexane phase transition was used to investigate the crosslinking extent in photo-oxidised ethylene propylene diene monomer (EPDM) samples by thermoporosimetry technique. Before apply this technique to EPDM, texturally well-known silica gel samples were used to calibrate the method. By contrast to the case of liquid-to-solid heptane transition, no linear relationship was obtained between the solid-to-solid point depression (Δ T) and the pore radius ( R p). The following correlation was obtained: R p ( A ̊ )=16.93+125.43 exp − 1/ ΔT+0.0756 0.0205 with 0> ΔT>−55 ° C. Pore size distributions (PSD), calculated by thermoporosimetry using the solid-to-solid transition, were in a good agreement with those obtained by gas sorption method (BJH). Elastomeric gels were assumed to be similar to a porous medium where the pore notion is replaced by the mesh notion. Using the same relations which were used to calculate the PSD, the mesh size distributions (MSD) were calculated for various EPDM samples crosslinked under irradiation. The width and the maximum of these MSD are related to the extent of crosslinking.

Analysis of EPDM Terpolymers by Near-Infrared Spectroscopy and Multivariate Calibration Methods

Near-infrared spectroscopy in the combination, first overtone, and second overtone regions is combined with the multivariate methods of Partial-Least-Squares (PLS) and Classical-Least-Squares (CLS) to provide calibrations for chemical components in ethylene-propylene-diene monomer (EPDM) terpolymers. EPDM samples with 1,4-hexadiene (HD) and ethylidene norbornene (ENB) diene monomers were used for this study. Because unknown interaction effects are present in the spectra of these materials, the PLS calibration method gives more accurate calibrations than the CLS method. PLS coefficient spectra and CLS reconstructed spectra obtained from the calibrations are used to determine the sources of the unknown spectral effects. Results indicate that the combination, first overtone, and second overtone regions of the spectrum can be used to determine ethylene and propylene concentrations in the terpolymers, and the combination region can be used to determine diene concentrations. The presence of intrachain and interchain interactions in the terpolymers is indicated by observation of CLS reconstructed spectra.