Ethylene Propylene Diene Methylene Research Articles

Study on radiation degradation of nuclear power cable materials

During the operation of nuclear power plants, it is necessary to monitor and evaluate the aging of cable materials. In this paper, we evaluate the irradiated use status of two types of cable insulation materials used in nuclear power plants-cross-linked polyethylene (XLPE) and ethylene propylene diene methylene (EPDM). Firstly, two kinds of cable materials are subjected to accelerated radiation aging with different cumulative doses, and the macro-mechanical properties and microstructure changes of the cable materials after different doses are studied. Analyze and test its hardness value, tensile strength, elongation retention at the break, scanning electron microscope, and oxidation induction temperature. The results show that after γ-ray irradiation, the cable hardness and the retention rate of elongation at break show a downward trend. Under the highest cumulative dose of 500kGy, the retention rate of elongation at break is greater than 50% of the failure index. The tensile strength decreases slightly, the microscopic morphology of the tensile section has holes, and the oxidation induction temperature decreases.

Excellent Adhesive Performance for the Thermal Insulation Attribute to Micromorphology Regulation and Controllable Injection of Oxygen‐Containing Groups by Low Temperature Plasma Treatment

AbstractA low temperature plasma (LTP) surface treatment technology operated under atmospheric conditions with air as the treatment atmosphere is developed for micromorphology regulation and controllable injection of oxygen‐containing groups on the surface of ethylene propylene diene methylene (EPDM) thermal insulation to achieve excellent adhesion performance. Optical emission spectroscopy is used to analyze the active species in the LTP. The key treatment parameters are optimized by contact angle measurements, resulting in thermal insulation sample with 3.32 times higher surface energy than the original sample. The surface morphology and composition of the samples are characterized. It is demonstrated that the surface of the thermal insulation shows new structures, thus increasing the surface area of the thermal insulation. In addition, a large number of oxygen‐containing groups are introduced to the surface of the thermal insulation, especially OH, and the O/C increases by 78.57%. Finally, the peel test is performed on the insulation samples with comparison to the grinding samples, which shows that the peel strength of the treated samples increases by 126.92%, while an additional 22% is also obtained compared to the grinding samples. This excellent adhesive performance is mainly caused by the synergistic effect of chemical crosslinking, hydrogen bonding, and mechanical interlocking.

Effect of novel sucrose based polyfunctional monomer on physico-mechanical and electrical properties of irradiated EPDM

In this work a novel sucrose based polyfunctional monomer (SPF) was prepared and evaluated as a co-agent in the radiation crosslinking of Ethylene propylene diene methylene linkage rubber (EPDM). The incroporation of SPF boosted the crosslink density which is reflected postively on the gel content and swelling resistance of irradiated EPDM. The mechnical properties of EPDM enhanced as the SPF content increased where the highst tensile strength and elastic modulus were recorded for EPDM which contains 5 phr of SPF. In addition, a decrease in the dielectric constant and an increase in the electrical resistivity of EPDM were observed as SPF content increases. The thermal stability of EPDM was improved after the addition of SPF, especially at temeperature lower than 400 °C.

Improving the adhesion strength of polymers: effect of surface treatments

To improve their adhesion strength, polymeric surfaces are usually modified through different treatments. This study investigates the effect of mechanical, chemical, and energetic treatments on the bonding strength of ethylene propylene diene methylene (EPDM), polyvinyl chloride (PVC), and acrylonitrile butadiene styrene (ABS) materials. Three adhesives based on different chemical compositions, namely silicone, polyurethane, and modified-silane (MS) polymer, were considered. Results show that the effect of the applied treatments on the adhesion strength of EPDM surfaces is insignificant. Only a slight improvement is obtained in the case of polyurethane-based adhesive, while the failure modes remained adhesive. As for PVC, most treatments were effective in the case of the silicone-based adhesive, especially grit blasting, primer, and UV/ozone treatments. Only UV/ozone treatment improved the adhesion strength and altered the failure mechanisms of this material when polyurethane and MS-based adhesives are used. The adhesion of ABS increased and the failure modes changed from adhesive to cohesive for most treatments. Particularly, a significant improvement is obtained when primer coating and UV/ozone radiation are applied. This comparative study paves the way for the design of polymeric joints with highly enhanced adhesion performance.

Effect of UV/ozone treatment on the wettability and adhesion of polymeric systems

ABSTRACT The impact of UV/ozone treatment on the wettability and adhesion of ethylene propylene diene methylene (EPDM) rubber, polyvinyl chloride (PVC), and acrylonitrile butadiene styrene (ABS) was investigated using contact angle measurements, OWRK surface free energy model, standardized adhesion tests, and spectroscopic and microscopic observations. It is found that UV/ozone treatment enhances the wettability of the examined polymers. Also, it considerably improved the adhesion strength of PVC and ABS samples, and shifted their failure modes from adhesive to cohesive. FTIR-ATR characterization showed insignificant changes in the chemical structures of the studied materials. However, SEM observation showed newly-created wrinkles and micro-holes on treated PVC surfaces, and micropores on ABS surfaces. These UV-induced morphological changes on PVC and ABS surfaces increased the surface area which can promote the mechanical interlocking with the adhesive. This explains the improvement of their adhesion strength. Implications of the current study for the processing of strongly bonded polymeric joints are discussed.

Optimization of Accelerator Mixing Ratio for EPDM Rubber Grommet to Improve Mountability Using Mixture Design

A grommet, made of ethylene propylene diene methylene (EPDM) rubber, is an integral part used for fixing and protecting the wire inserted from the outside to the inside of vehicles. Rubber compounds exhibit various mechanical properties and vulcanization characteristics depending on the accelerator mixing ratio. These mechanical properties affect the insertion and detachment forces when the grommet is manufactured and fixed to the vehicle body. In this study, we experimentally analyzed the changes in the properties of EPDM rubber depending on the vulcanization accelerator to improve the mounting performance of the grommet, and subsequently derived the optimum accelerator mixing ratio. We implemented a mixture design strategy to derive the optimum mixing ratio for obtaining the desired mechanical properties and vulcanization characteristics. The insertion and separation forces of the existing grommet were compared with those of the grommet fabricated using the derived mixing ratio and we found that the mounting performance was improved compared to the existing grommet.

Short-term organic carbon migration from polymeric materials in contact with chlorinated drinking water

Polymeric materials are widely used in drinking water distribution systems. These materials could release organic carbon that supports bacterial growth. To date, the available migration assays for polymeric materials have not included the potential influence of chlorination on organic carbon migration behavior. Hence, we established a migration and growth potential protocol specifically for analysis of carbon migration from materials in contact with chlorinated drinking water. Four different materials were tested, including ethylene propylene dienemethylene (EPDM), poly-ethylene (PEX b and PEX c) and poly-butylene (PB). Chlorine consumption rates decreased gradually over time for EPDM, PEXc and PB. In contrast, no free chlorine was detected for PEXb at any time during the 7 migration cycles. Total organic carbon (TOC) and assimilable organic carbon (AOC) was evaluated in both chlorinated and non-chlorinated migrations. TOC concentrations for EPDM and PEXb in chlorinated migrations were significantly higher than non-chlorinated migrations. The AOC results showed pronounced differences among tested materials. AOC concentrations from chlorinated migration waters of EPDM and PB were higher compared to non-chlorinated migrations, whereas the opposite trend was observed for PEXb and PEXc. There was also a considerable difference between tested materials with regards to bacterial growth potential. The results revealed that the materials exposed to chlorine-influenced migration still exhibited a strong biofilm formation potential. The overall results suggested that the choice in material would make a considerable difference in chlorine consumption and carbon migration behavior in drinking water distribution systems.

Mechanical and rheological properties of calcium carbonate-filled ethylene propylene diene elastomer reinforced by metallic acrylate salt

High performance ethylene propylene diene methylene elastomer (EPDM)/calcium carbonate (CaCO )/aluminum triacrylate (ALTA) hybrids have been prepared by a melt compounding process. The mechanical properties of the peroxide cured EPDM/CaCO /ALTA vulcanizates were investigated by tensile, hardness, resilience, abrasion and fatigue life tests. The results showed that the ALTA can greatly improve the modulus at 100 %, tensile strength, abrasion resistance and fatigue life of the EPDM/CaCO /ALTA vulcanizates, while retaining their high elongation at break. ALTA as a reactive filler had accelerating effect on the vulcanization reaction of and increased the crosslink density of the EPDM/CaCO composites. This phenomenon is due to increasing the ionic bonds arise from both homo-polymerization of ALTA and graft co-polymerization of it onto the EPDM. Scanning electron microscopy (SEM) revealed the presence of ALTA causes to the roughness of the fracture surface of CaCO -filled EPDM compounds demonstrating high interaction between the fillers and EPDM improved by introduction of ALTA. Dynamic mechanical analysis revealed that the glass transition temperature (T ) and dissipation peak (tan δ) of EPDM composites decreases with increasing ALTA content. Decrease in tan δ value and inward shifting of T were related to improved interaction of filler and EPDM.

Thermal conductivity and thermal stability enhancement of ethylene propylene diene methylene with carbon nanotube

In this article, the ethylene propylene diene methylene rubber composites filled with pretreated multi-walled carbon nanotubes were prepared by a double-roll milling dispersion method. The thermal and mechanical properties of the composites were measured and evaluated. The morphology of pretreated multi-walled carbon nanotubes was studied via transmission electron microscopy and the dispersity of multi-walled carbon nanotubes in ethylene propylene diene methylene was determined using scanning electron microscope. By means of thermogravimetric analysis, the thermal stability and oxidation resistance of ethylene propylene diene methylene filled with different content of multi-walled carbon nanotubes were examined. The results showed that the pretreated multi-walled carbon nanotubes can improve the thermal conductivity and increase the thermal decomposition temperature. However, different filling content of multi-walled carbon nanotubes showed different effects on the mechanical performance of ethylene propylene diene methylene.

Influence of carbon black on decompression failure and hydrogen permeation properties of filled ethylene‐propylene–diene–methylene rubbers exposed to high‐pressure hydrogen gas

AbstractEight carbon black (CB)‐filled ethylene–propylene–diene–methylene linkage (EPDM) rubbers were manufactured by varying the content and type of CB. Then, the relationship among crack damage caused by high‐pressure hydrogen decompression, the hydrogen permeation properties, and the mechanical properties of the rubbers was investigated. The hydrogen gas permeability of the rubbers decreased with an increase in the CB content and depended little on primary particle size. In contrast, the hydrogen gas diffusivity and solubility depended on both the CB content and primary particle size, that is, the hydrogen gas diffusivity decreased with an increase in the CB content and a decrease in the primary particle size, and the hydrogen gas solubility increased with an increase in the CB content and a decrease in the primary particle size. As for the mechanical properties, the CB‐filled rubbers were more strongly reinforced by an increase in the CB content and a decrease in the primary particle size. The crack damage by high‐pressure hydrogen decompression became larger as the ratio of the hydrogen gas solubility to estimated internal pressure at crack initiation relating to the mechanical properties became larger. As a smaller CB particle increases the hydrogen gas solubility of EPDM rubbers, while at the same time it reinforces the rubbers, the crack damage in the CB‐filled rubbers was not influenced by the primary particle size. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Nanoscale fracture analysis by atomic force microscopy of EPDM rubber due to high-pressure hydrogen decompression

The relationship between internal fracture due to high-pressure hydrogen decompression and microstructure of ethylene–propylene–diene–methylene linkage (EPDM) rubber was investigated by atomic force microscopy (AFM). Nanoscale line-like structures were observed in an unexposed specimen, and their number and length increased with hydrogen exposure. This result implies that the structure of the unfilled EPDM rubber is inhomogeneous at a nanoscale level, and nanoscale fracture caused by the bubbles that are formed from dissolved hydrogen molecules after decompression occurs even though no cracks are observed by optical microscopy. Since this nanoscale fracture occurred at a threshold tearing energy lower than that obtained from static crack growth tests of macroscopic cracks (Ts,th), it is supposed that nanoscale structures that fractured at a lower threshold tearing energy (Tnano,th) than Ts,th existed in the rubber matrix, and these low-strength structures were the origin of the nanoscale fracture. From these results, it is inferred that the fracture of the EPDM rubber by high-pressure hydrogen decompression consists of two fracture processes that differ in terms of size scale, i.e., bubble formation at a submicrometer level and crack initiation at a micrometer level. The hydrogen pressures at bubble formation and crack initiation were also estimated by assuming two threshold tearing energies, Tnano,th for the bubble formation and Ts,th for the crack initiation, in terms of fracture mechanics. As a result, the experimental hydrogen pressures were successfully estimated.

Characterization of EPDM Vulcanizates Modified with Gamma Irradiation and Trichloroisocyanuric Acid and Their Adhesion Behavior with Natural Rubber

The adhesion strength between surface-modified vulcanized ethylene propylene diene methylene (EPDM) rubber and unmodified natural rubber (NR) was investigated by a 180° peel test. Surface modification of EPDM vulcanizate was carried out by two different techniques: (a) irradiation of the surface by gamma radiation in the presence and absence of trimethylol propane triacrylate (TMPTA) as a sensitizer and (b) chemical treatment of the surface with trichloroisocyanuric acid (TCICA). The modified EPDM surface was thoroughly characterized by attenuated total reflection infrared spectroscopy (ATR-IR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive X-ray sulfur mapping (EDX), surface energy measurements, and free sulfur and gel content analysis. The joint between the modified vulcanized EPDM and the unmodified unvulcanized NR was prepared by a co-curing method. The adhesion strength between these two surfaces was found to depend on the nature of oxidation, roughness of the joining surfaces, and extent of blooming of sulfur on the modified surface. Surface modification of EPDM sample with 1 kGy of gamma irradiation in the presence of 10 wt% TMPTA resulted in a good increase in the adhesion strength between EPDM and NR (∼76% improvement over the untreated sample). On the other hand, for the trichloroisocyanuric acid modified sample, maximum improvement of adhesion strength was observed at 0.5 wt% of TCICA (∼29% improvement in comparison with the untreated sample).

Adhesion of Vulcanized Rubber Surfaces: Characterization of Unmodified and Electron Beam Modified EPDM Surfaces and Their Co-vulcanization with Natural Rubber

Peel adhesion behavior of unmodified and modified ethylene propylene diene methylene (EPDM) vulcanizates covulcanized with gum natural rubber (NR) is reported in this paper. Modification of the vulcanizate surface has been carried out by electron beam (EB) irradiation with or without EB sensitizers such as trimethylol propane triacrylate (TMPTA) and tripropylene glycol diacrylate (TPGDA). The doses of both EB and TMPTA/TPGDA have been varied in separate experiments keeping one of them constant. The surface features have been analyzed using several analytical techniques like attenuated total reflection infrared spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy, scanning electron microscopy, energy dispersive X-ray sulphur mapping, surface energy measurements, free sulphur and gel content analysis. In comparison to its unmodified EPDM vulcanizate counterpart, 100 kGy modified EPDM vulcanizate in presence of 10 wt% TMPTA shows a maximum increase in O/C ratio value from 0.01 to 0.14. High energy irradiation leads to oxidation, grafting, breakdown of cross-links and blooming, which have been quantified. The joint strength of the modified and unmodified vulcanized EPDMs with gum NR has been tested at room temperature and is found to be a strong function of the nature and extent of the modification and surface roughness. The 10 wt% TMPTA soaked EPDM vulcanizate irradiated at 100 kGy has shown the highest peel strength (71% over that of the untreated sample) among all the samples.

Thiocompounds as simulants of sulphur mustard for testing of protective barriers

The protective potential of protective devices such as respirators, suits, gloves, and overboots is widely evaluated using the standard colorimetric test (spot disc breakthrough time test, also called SD BTT) involving sulfur mustard (SM) as the challenge chemical. The vesicant nature of SM makes the test inconvenient and poses stringent safety demands. Moreover, such tests are allowed only at a limited number of facilities, causing delay in product development and supply. This prompted the present study on the search for suitable SM simulant responsive to SD BTT test. The diffusivities at BTT (DBTT) of 10 commercially available thiocompounds through butyl rubber (IIR) were compared vis-a-vis DBTT of SM. For three representative thiocompounds, namely methyl (phenyl thio)acetate, 2-chloroethyl phenyl sulfide (2-CEPS) and phenyl-n-propyl sulfide (PNPS), the transport parameters through IIR were obtained. PNPS and 2-CEPS were further compared with respect to DBTT in elastomers such as IIR, ethylene–propylene–diene methylene rubber, polydimethylsiloxane, nitrile rubber, polybutadiene, and natural rubber. 2-CEPS showed generally same order of DBTT as SM implying its potential use as a simulant. The transport parameters for various 2-CEPS/elastomer systems were also determined. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Properties of vulcanized rubber nanocomposites filled with nanokaolin and precipitated silica

One kind of nanokaolin (NK) powder with 20–50 nm average thickness, 300–500 nm average diameter, and 32 m 2/g specific surface area, has been introduced into four types of rubber, specifically styrene butadiene rubber (SBR), natural rubber (NR), butadiene rubber (BR) and ethylene–propylene diene methylene (EPDM). Their reinforcing effects were evaluated by comparisons with those from precipitated silica (PS). The curability, mechanical properties, microstructure and the thermal stability of a variety of composites based on these rubbers were studied. This was done using vulcanization techniques, mechanical testing, thermogravimetric analysis (TGA), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The results showed that NK can greatly improve the vulcanizing process by shortening the time to optimum cure ( t 90) and prolonging the setting-up time ( t 10) of cross-linked rubbers, which improves production efficiency and operational security. The rubber composites filled with nanokaolin were found to have good mechanical properties, thermal stabilities, and elastomeric properties. The tensile strengths of the rubber/NK composites are close to those of rubber/PS composites, but the tear strength and modulus are not as good as the corresponding properties of those containing precipitated silica. Microstructural results revealed that the NK sheets are well dispersed in the rubber matrix in the parallel arrangement. The good interfacial interactions between the NK and the rubber chains give these rubber composites excellent processability, mechanical properties, and thermal stability.

クロロスルホン化ポリエチレンとエチレンプロピレンゴムの疲労強度と粘弾性特性の温度劣化挙動

Among many other uses, rubber is used in tubes and wire covers. Rubber exhibits considerable changes in mechanical properties over time and in temperature. To confirm the reliability of these products, we must evaluate how they degrade in humidity, sunlight, and under thermal loading. We therefore studied the thermal degradation of chlorosulfonated polyethylene rubber (CSM) and ethylene propylene diene methylene linkage (EPDM). We first measured thermal reduction of elongation and of fatigue strength of CSM and EPDM. To evaluate the degrading of these properties, we used Arrhenius's equation to confirm the relationship between temperature and exposure time. Using these evaluation methods we could predict thermal reduction of fatigue strength by taking into account the temperature and exposure time. The acceleration in thermal degradation of elongation and that of fatigue strength agreed well quantitatively. We next measured the viscoelastic behavior of virgin CSM and EPDM material and of thermally degraded material. We evaluated the thermal degradation of mechanical loss tangent by using Arrhenius's equation to confirm the relationship between the temperature and the time. The acceleration in thermal degradation of a mechanical loss tangent was in good agreement with the acceleration in thermal degradation of elongation and of fatigue strength.

Preparation and properties of EPDM–clay hybrids

Ethylene propylene diene methylene linkage rubber (EPDM)–clay hybrids have been prepared by mixing with EPDM and organophilic clay via vulcanization process. When we used thiuram and dithiocarbamate for the vulcanization accelerator, EPDM–clay hybrid was prepared successfully. In this EPDM–clay hybrid, the silicate layers of the clay were exfoliated and almost dispersed to the monolayers. The tensile strength of the EPDM–clay hybrid loading 4wt% clay exhibited 2.0 times higher value compared to that of neat EPDM at 25°C. The storage moduli (E′) of the EPDM–clay hybrid were also higher than that of neat EPDM. The gas permeability of EPDM–clay hybrid decreased 30% as compared with neat EPDM.

Dynamic mechanical properties of single-ply roof coverings for low-slope roofs and the influence of water

The results of five different commercial single-ply roof-covering products for low-slope roofs, i.e. atactic polypropylene (APP)-modified bitumen, styrene-butadiene-styrene copolymer (SBS)-modified bitumen, ethylene-copolymerized bitumen (ECB), plasticized PVC and ethylene-propylene-diene-methylene (EPDM)-rubber, studied by dynamic mechanical thermal analysis are summarized in this paper. Two samples of each product were tested, one which had only been conditioned at 20 °C, 50% relative humidity, and another which had been immersed in distilled water at 50 °C for 4000 h. The difference in the dynamic properties at the glass transition region of the two samples is discussed. The influence of water immersion on material properties such as T g and T onset was observed for the products of APP-modified bitumen, SBS-modified bitumen and plasticized PVC. The changes in these material properties may have significance for the durability of the products. Dynamic mechanical thermal analysis can be a useful tool for characterizing products used for single-ply roof coverings of low-slope roofs. It may be useful in understanding how different types of products behave in application with different types of dynamic stresses.