Propylene Diene Terpolymer Rubber Research Articles

Influence of permanent deformation on the fitting quality and the simulation prediction of filled elastomers

This work deals with the consequence of fitting hyperelastic material models to quasi-static multi-hysteresis test data with and without the correction of permanent deformation. Multi-hysteresis experiments are performed in different deformation states with equivalent amplitudes and equivalent strain rates. The investigations are performed on a carbon black filled ethylene propylene diene terpolymer rubber (EPDM). A second order polynomial hyperelastic material model was used to investigate the effect of elimination of permanent deformation during the fitting process. We find that the elimination of permanent deformation leads to a prediction of a stiffer material behavior. The validation of the obtained fitting parameters in the double-sided shear and uniaxial tension–compression loadings clearly shows that the elimination of the permanent deformation has a huge influence on the predicted stress field and strain field.

Crack growth angle prediction of an internal crack under mixed mode load for unfilled elastomer using the strain energy density factor

ABSTRACTThis article investigates the prediction of the crack growth angle of an existing internal crack under mixed mode loading at the crack tip for an unfilled ethylene propylene diene terpolymer rubber (EPDM). For the realization of mixed mode loading, the cracks of the uniaxial loaded specimens were oriented with different angles to the loading direction. The energy density factor was used as a potential criterion for determining the crack growth angle. The determination of the strain energy density factor was carried out simulatively in Abaqus. The second‐order Ogden model was used to describe the rubber‐like material behavior. The relative local minimum of the strain energy density factor provides the possible growth angle. The experimental investigations show that the initial cracks grow orthogonally to the loading direction for the different crack orientation angles. For the crack orientation angle parallel to the load direction, the crack growth was observed because the strong stretching of the specimen caused strong necking in the crack region. The crack growth for the remaining crack orientation angles were induced due to shear loading at the crack tip. The predictive angle of different crack orientation angles shows very good accordance to the measured crack growth angles.

A nitrile functionalized graphene filled ethylene propylene diene terpolymer rubber composites with improved heat resistance

Abstract Ethylene propylene diene terpolymer rubber (EPDM) is susceptible to temperature, and heat can greatly increase the molecular mobility which degrades the mechanical properties of a rubber part. To overcome this problem, EPDM composites containing various nitrile functionalized graphene (GN-CN) were prepared and investigated for the effects of surface modification on the mechanical properties under low and high temperature. Results indicated that, the tensile strength of 3phr GN-CN filled EPDM composite reaches 11.8 and 6.0 MPa at 25 °C and 70 °C, respectively, which is 63.9% and 100% higher than that of unfilled one. Meanwhile, the strength loss of the EPDM/GN-CN composite under 70 °C is 49.1%, which is 9.2% lower than that of EPDM. It was demonstrated that, the reaction of the nitrile groups is benefit to the tensile strength and heat resistance improving of EPDM.

Effect of gamma radiation on the physicomechanical characters of EPDM rubber/modified additives nanocomposites

Ethylene propylene diene terpolymer (EPDM) rubber nanocomposites have been prepared by incorporating 10 phr of organically modified montmorillonite (OMMT) nanoclay and various percentages of fumed silica (10, 20, and 30 phr) onto EPDM rubber composite using two roll mill and crosslinked by gamma radiation. The effect of radiation dose on the mechanical properties namely tensile strength and elongation at break and the physical properties namely solubility and swelling were investigated. Thermogravimetric analysis was carried out to analyses the thermal stability of the nanocomposites. Volume resistivity of the nanocomposites was also measured. The results showed that the mechanical, volume resistivity, and thermal properties of the irradiated EPDM rubber containing OMMT were increased by adding of the fumed silica. The effect of N,N‐m‐phenylenedimaleimide coagent on the mentioned properties of the EPDM rubber nanocomposites was studied. The results showed that the physical, mechanical, and thermal properties of the irradiated EPDM rubber nanocomposites improved with the addition of the coagent due to the increase of the crosslinking density. The inclusion of both the 30 phr fumed silica and the coagent in the nanocomposite irradiated to 50 kGy leads to a synergistic effect. J. VINYL ADDIT. TECHNOL., 23:E188–E200, 2017. © 2016 Society of Plastics Engineers

Synergistic effect of graphene nanoplatelets and carbon black in multifunctional EPDM nanocomposites

Ethylene–propylene–diene terpolymer rubber (EPDM)-based nanocomposites containing carbon black (CB), graphene nanoplatelets (GNPs), and mixtures of the two fillers were prepared. The influence of the relative amounts of the two fillers on the dynamic and static friction coefficients was examined. The static analysis of the coefficient of friction suggests that the partial substitution GNPs into the EPDM/CB blend did not produce a significant variation of the surface grip. The sample comprising EPDM/CB composite and an effective amount of GNPs dispersed in the matrix provides an increase of the thermal conductivity, damping (i. e. shock absorbing properties) and mechanical properties of the nanocomposites. The field-emission scanning electron microscopy and micro tomography analyses showed that the replacement of CB with GNPs reduces the CB aggregation and, hence, improving the percolation of the hybrid fillers and the interface resistance of the composite. The development of thermally conducting elastomeric nanocomposites could envisage their utilization in the processing of rubber blends satisfying the increasing demand to reduce both the duration of the vulcanization process and thus the cost of the vulcanized rubbers.

Pyroshock testing on graphene based EPDM nanocomposites

Ethylene–propylene–diene terpolymer rubber (EPDM) and graphene nanoplatelets (GNPs) nanocomposites were prepared via a vulcanization process. The mechanical and thermal properties of the nanocomposites were studied. Curing studies demonstrated the increase in maximum torque for the GNP loaded EPDM compounds compared to carbon black loaded EPDM. A high magnitude and a high frequency transient loading, a pyroshock event, was applied to the prepared samples. The acceleration time history measured in the impact excitation test and a simplified analysis model based on the frequency response analysis, were established for evaluating the shock response of the nanocomposites. Experimental results indicated that the interfacial interaction between GNPs and EPDM matrix results in enhancements in damping property. This experimental approach can be used to test the potential utilization of such polymer nanocomposites to be used for space or military components subjected to high-frequency, high-magnitude shock pulses.

Structural characteristics of some high density polyethylene/EPDM blends

Blends of ethylene propylene diene terpolymer rubber (EPDM) with high density polyethylene were obtained by melt mixing. Mechanical properties of the composites, tensile strength, hardness, resilience, elongation at break, 100% modulus and tear strength were determined. Differential scanning calorimetry and wide angle x-ray diffraction were employed to study melting behavior and crystalline structure. The surface properties were analyzed using contact angle determinations. Also, compatibilization with PE-g-MA or dynamical vulcanization using phenolic resins was applied to obtain improved mechanical properties. It was found that the crystalline structure of HDPE was not changed during blending. The vulcanized composite presents a lower degree of crystallinity. Elongation at break and hardness were significantly increased for composites containing compatibilizing agent. The morphology of EPDM composites was studied by atomic force microscopy.

Mechanical Properties and Tensile Deformation Behavior of Polyamide 6/Maleated and Unmaleated Ethylene Propylene Diene Terpolymer/Nano-CaCO3 Ternary Composites

Ternary composites composed of polyamide 6 (PA6), a mixture of maleated (EPDM-g-MA) with unmaleated ethylene propylene diene terpolymer (EPDM) rubber at weight ratio 80/20 (defined as EPDM-M), and nano-calcium carbonate (nano-CaCO3) were prepared by a two-step compounding route. Sandbag microstructure, in which nano-CaCO3 agglomerates were embedded EPDM-M, were observed by scanning electron microscopy (SEM). Deformation of the composites was studied by video-aided tensile tests during uniaxial tension. The microstructural morphology and interfacial interaction were investigated through SEM and dynamic mechanical analysis (DMA). Compared to PA6/EPDM-M/nano-CaCO3 ternary composites without sandbag microstructure (E2), the microstructural morphology of PA6/EPDM-M/nano-CaCO3 ternary composites with sandbag microstructure (E3) showed that numerous microfibrils and cavitations were formed by simultaneously stretching and debonding of nano-CaCO3 agglomerates and EPDM-M in the sandbag microstructure, which resulted in a higher volume strain and larger quantity of energy dissipation. Additionally, better interfacial interaction between the sandbag microstructure and PA6 matrix in E3 caused a lower α-relaxation temperature and easier external energy transmission than E2 without sandbag microstructure. Consequently, the presence of the sandbag particles in PA6/EPDM-M/nano-CaCO3 ternary composites changed the tensile yield deformation of PA6 from a more deviatoric plasticity to a more dilatational plasticity.

Effect of Rubber–Filler Interaction on Transport of Aromatic Liquids through High Density Polyethylene/Ethylene Propylene Diene Terpolymer Rubber Blends

The sorption and transport of four aromatic hydrocarbons through dynamically vulcanized high density polyethylene/ethylene propylene diene terpolymer rubber blends filled with carbon black and that filled with silica at the same loading have been investigated in the temperature range of 28–58 °C by an equilibrium swelling technique . Blends loaded with high abrasion furnace (HAF) black and those with silica of same loading have been used. The silica-incorporated blends sorbed a higher amount of aromatic solvents compared with the HAF filled blends. This has been explained in terms of the differences in the interaction between the filler particles and the blend components. The swelling coefficient, diffusion coefficient, and molar mass between cross-links have been computed to complement the experimental observations.

Effect of aluminium hydroxide, chlorinated polyethylene, decabromo biphenyl oxide and expanded graphite on thermal, mechanical and sorption properties of oil-extended ethylene–propylene–diene terpolymer rubber

Oil-extended EPDM composites with different flame retardant fillers like aluminium hydroxide (ATH), chlorinated polyethylene (CPE), decabromobiphenyl oxide (DBBO) and expanded graphite (EG) were prepared by conventional mill mixing. Thermal, mechanical and sorption characteristics of the vulcanizates were studied. The effect of different fillers on the flammability of the composites was measured using Limiting Oxygen Index (LOI) and UL-94 HB tests. Scanning Electron Microscopic (SEM) studies of the composites were also conducted. ATH and CPE improve the thermal stability of the composite substantially. Among the four fillers ATH has the highest reinforcing effect on the EPDM rubber. Sorption studies of the composite showed that ATH reduced the swelling rate of the microcomposite considerably. All the four fillers were effective in improving the flame retardant property. Filler dispersion studies and SEM images point to a uniform dispersion of filler in the matrix which is in good agreement with significant improvement in mechanical properties.

Permeation of Chlorinated Hydrocarbon Vapors through High Density Polyethylene/Ethylene Propylene Diene Terpolymer Rubber Blends

Polymer membranes were prepared by blending high density polyethylene (HDPE) with ethylene propylene diene terpolymer rubber (EPDM) and were tested for vapor permeation characteristics. The variation in sorption, diffusion, and permeation coefficients with blend composition has been studied and it was found that in these blends the permeability coefficient and sorption coefficients increased with increase in EPDM concentration. The permeation rate decreased with the increase in molecular mass of the penetrants. The permeability of the HDPE/EPDM blends vulcanized with three different vulcanizing systems has been studied and found that as the degree of crosslinking increases, the permeability decreases. The permeability measurements provide useful information on the morphology changes with composition of the blends and on the composition corresponding to the maximum level of co-continuity of the two phases.

Electron-induced reactive processing of thermoplastic vulcanizate based on polypropylene and ethylene propylene diene terpolymer rubber

Thermoplastic vulcanizate (TPV) was prepared by in situ cross-linking of the rubber phase by high-energy electrons during melt mixing with a thermoplastic. The electron accelerator was directly coupled with the mixing device to cross-link the rubber phase in situ. The effect of the electron energy and absorbed dose per rotation on the properties and morphology of the TPV was studied. An absorbed dose of 100 kGy and a dose per rotation of 90 kGy per rotation resulted in a TPV with the best set of mechanical properties, as confirmed by morphological analysis too. The effect of different blend ratios was also studied, and it was found that a 50:50 blend ratio produced TPV with superior mechanical properties compared with 30:70 blends, as confirmed by the morphological analysis. A mechanism for the observed improvement in mechanical properties was proposed, based on the viscosity ratio of the blend components and the blend ratio. Finally, the effect of the premixing time of the blend components on the mechanical properties and morphology before the electron-induced reactive processing (EIReP) was studied. A premixing time of 14 min was required to achieve the optimum dispersion of the rubber phase in the thermoplastic phase before in situ cross-linking. EIReP of ethylene propylene diene monomer (EPDM)/polypropylene (PP) blends presents a novel approach where the EPDM phase is cross-linked and grafted to PP by high-energy electrons without any coagent during melt mixing with PP. In the present work, the effect of absorbed dose, absorbed dose per rotation, and of different blend ratios on the properties and morphology of PP-EPDM TPVs is discussed in detail. The effect of premixing time is also discussed to observe its influence on the morphology and final properties of the TPVs prepared.

Roofing Assembly Simulated Heat and Light Test

Abstract The goal of this project is to search for a testing procedure for roof covering products that will radiate both heat and light onto a roof covering and then measure the impact that a given roof covering product has on heat transfer through the entire roofing assembly. Identical roof assemblies were built with ethylene propylene diene terpolymer (EPDM) rubber roof membrane over a wood deck. Sixteen heat lamps were positioned 1.14 m [45 in.] above the roof covering product to provide both heat and light. Thermocouples were placed on the underside of the wood deck and were insulated from outside air. The roofing assembly and the roof covering temperatures were brought to 18°C to 21°C prior to testing. Heat and light were radiated onto the roof coverings for 360 min and the under deck temperature was recorded at 1 min intervals for 600 min. Tested roof coverings included gravel, growing media, coatings, and panels in the form of concrete, ceramic foam, and rubber. The results of the tests have shown data similar to that which were recorded during warm, sunny days. As expected, the highest temperatures were achieved by the uncovered and uncoated black EPDM roof assembly. The temperature of this assembly diminished almost immediately upon the removal of the heat and light source. Thicker layers of growing media and ceramic foam block did not reach the peak temperature until several hours after the heat lamps were turned off. The roof assembly covered with reflective coating showed realistic resistance to the heat and light source. This is a significant advancement in the effort to provide equitable data for all roof coverings. The test provides a standard method of collecting data for traditional roof coverings as well as emerging technology roof covering materials to evaluate a roofing assemblies’ thermal performance from solar heat gain.

Transport behavior of aromatic hydrocarbons through high density polyethylene/ ethylene propylene diene terpolymer blends

Membrane based separation technology is currently regarded as a new frontier of chemical engineering and widely used for the purification, concentration and fractionation of fluid mixtures. Polymer blend membranes are promising materials that can overcome the difficulties associated with homopolymer systems and hence the selection of polymer blend membrane as a novel material for various applications is worth probing. Transport properties of aromatic hydrocarbons through a new class of membranes from blends of high density polyethylene (HDPE) and ethylene propylene diene terpolymer rubber (EPDM) have been investigated at different temperatures to understand the effect of physical and chemical nature of the polymer blend on the transport phenomena. The effects of blend ratio, temperature and penetrant size on the sorption properties were studied. The equilibrium solvent uptake decreases with an increase in concentration of HDPE, in the blends. Relationship between transport behavior and the morphology of the system was examined. The mechanism of transport has been analyzed and found that the mode of transport is close to Fickian. The sorption data have been used to estimate the transport coefficients and various kinetic parameters of sorption.

Transport properties of high-density polyethylene/ethylene propylene diene terpolymer blends

Polymer blends based on high-density polyethylene and ethylene propylene diene terpolymer rubber (EPDM) were prepared. The sorption and diffusion of four aliphatic hydrocarbons through the blends were studied in the temperature range of 28–58 °C. Sulfur, dicumyl peroxide (DCP), and a mixture of sulfur and DCP (mixed) were used as cross-linking agents for the blends. Of the three systems, the peroxide vulcanized blends were found to exhibit the lowest penetrant uptake. This has been explained based on the higher rigidity of the –C–C– networks than the polysulfide linkages. The aliphatic liquid penetration through the matrix increased with increase in the EPDM content in the blend. The experimental observations were correlated with the morphology of the blends. Diffusion and permeation coefficients were calculated from the sorption data. A slight deviation from the Fickian trend was observed for the mechanism of transport with an increase in EPDM in the blends. The molar mass between cross-links and thermodynamic parameters of sorption was determined from the swelling data. The experimental observations were compared with various theoretical models.

Effect of the Surface Morphology of Calcium Carbonate on the Impact Toughness of Polyamide 6/EPDM-M/CaCO3 Ternary Composites

Ternary composites of polyamide 6 (PA6), mixed with unmaleated ethylene propylene diene terpolymer rubber (named as EPDM-M) and calcium carbonate (CaCO3, with three different kinds of surface morphology) were prepared via two-step melt blending process. The influence of surface morphology of CaCO3 on the impact toughness of PA6/EPDM-M/CaCO3 was investigated. It was found that the Izod impact strength of the composites improved with increasing of the surface area of CaCO3. The characterization of CaCO3 by BET tester and scanning electron microscope (SEM) obviously showed that both needle-shaped CaCO3 and spherical CaCO3 were have a bigger specific surface area and rougher morphology than ground CaCO3. So they have a better toughen effect, which was well explained the results of impact test. Morphology observed on the impact fracture revealed that the formation of voids by the debonding of CaCO3, which could trigger the matrix emerged obvious plastic deformation in the composites that included needle-shaped CaCO3 or spherical CaCO3. This phenomenon also can be demonstrated that needle-shaped CaCO3 and spherical CaCO3 had superior toughen effective. Consequently, the surface morphology of CaCO3 had a distinctive effect on the toughness of PA6/EPDM-M/CaCO3 Composites.

Separation of n-hexane/acetone mixtures by pervaporation using high density polyethylene/ethylene propylene diene terpolymer rubber blend membranes

Polymer membranes were prepared by blending high density polyethylene (HDPE) with ethylene propylene diene terpolymer rubber (EPDM). These blend membranes were evaluated for the selective separation of n-hexane from acetone. The flux and selectivity of the membranes were determined both as a function of the blend composition and feed mixture composition. Results showed that polymer blending method could be very useful to develop new membranes with improved selectivity. Pervaporation properties could be optimized by adjusting the blend composition. The effects of blend ratio, feed composition, and penetrant size on the pervaporation process were analyzed. The permeation properties have been explained on the basis of interaction between the membrane and solvents and blend morphology. Flux increases with increasing alkane content in the feed composition.

The Toughening Mechanism of Polyamide 6/EPDM-M/Nano-CaCO<sub>3</sub> Ternary Composites with Sandbag Microstructure

Ternary composites of Polyamide 6 (PA6), the mixture of Maleated and Unmaleated Ethylene Propylene Diene terpolymer rubber (named EPDM-M), and nanoCalcium Carbonate (nanoCaCO3) were prepared by one-step and two-step compounding routes. The toughness of the composites was tested by impact test. The microstructure morphology of impact surface and etched impact surface was investigated through scanning electron microscope (SEM). The result shows that toughness of the ternary composites with sandbag microstructure was 270 % higher than neat PA6. The SEM morphology shows that strongly elongated microfibrils and deformation are formed in ternary composite with sandbag microstructure, which cause larger shear yielding and crazes in the surrounding matrix to dissipate more impact energy. Additionally, strong ligaments are observed at the crack tip, which could promote plastic deformation and consumption of fracture energy.

Preintercalation of an organic accelerator into nanogalleries and preparation of ethylene propylene diene terpolymer rubber–clay nanocomposites

A multifunctional additive, bis(diisopropyl) thiophosphoryl diisopropyl disulfide (DIPDIS), was melted in the presence of quaternary ammonium-modified montmorillonite clay and incorporated into an ethylene propylene diene terpolymer (EPDM) rubber matrix as a nanofiller to prepare EPDM rubber nanocomposites. The finer dispersion of the organoclay (OC) in the rubber matrix was observed when the OC was preintercalated by DIPDIS using the propping-open procedure. X-ray diffraction (XRD) results showed that the silicate layers of the OC were successfully preintercalated by the DIPDIS; that is, the basal spacing of clay galleries was expanded from 2.98 to 3.76 nm. Because of the larger interlayer distance, as evidenced by XRD studies, the delamination process was facilitated through the easy intercalation of macromolecular rubber chains, which was reflected in various properties, such as the stress–strain behavior, thermal stability, dynamic mechanical properties and swelling properties. XRD studies and transmission electron microscopy directly supported the effective filler dispersion in the non-polar EPDM rubber matrix.

Radiation processed polychloroprene–co-ethylene-propene diene terpolymer blends: Effect of radiation vulcanization on solvent transport kinetics

Blends of polychloroprene rubber (PCR) and ethylene propylene diene terpolymer rubber (EPDM) of different compositions were made and exposed to different gamma radiation doses. The radiation sensitivity and radiation vulcanization efficiency of blends was estimated by gel-content analysis, Charlesby-Pinner parameter determination and crosslinking density measurements. Gamma radiation induced crosslinking was most efficient for EPDM ( p 0/ q 0 ∼ 0.08), whereas it was the lowest for blends containing 40% PCR ( p 0/ q 0 ∼ 0.34). The vulcanized blends were characterized for solvent diffusion characteristics by following the swelling dynamics. Blends with higher PCR content showed anomalous swelling. The sorption and permeability of the solvent were not strictly in accordance with each other and the extent of variation in two parameters was found to be a function of blend composition. The Δ G values for solvent diffusion were in the range −2.97 to −9.58 kJ/mol and indicated thermodynamically favorable sorption for all blends. These results were corroborated by dynamic swelling, experimental as well as simulated profiles and have been explained on the basis of correlation between crosslinking density, diffusion kinetics, thermodynamic parameters and polymer–polymer interaction parameter.