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Promising nanocomposites (EPDM-nRHP) were prepared from EPDM/ nanosized rice husk powder (nRHP) in the presence of HRH system as modifying dry bonding agent. HRH system comprised hydrated silica, resorcinol and hexamethylenetetramine. Different concentrations from nRHP were used for preparing such nanocomposites. The effect of nRHP was studied on the mechanical and dielectric properties of EPDM-nRHP nanocomposites whether in the presence or absence of HRH system. The presence of HRH modifying system enhanced the dispersion of nRHP in EPDM and consequently improved the mechanical and dielectric properties for the resulting EPDM-nRHP nanocomposites which may be used as electrical insulator. [ABSTRACT FROM AUTHOR]

Mullins effect and its reversibility of ethylene–propylene–diene terpolymer/carbon black vulcanizate and polypropylene/ethylene–propylene–diene terpolymer thermoplastic vulcanizate under compression mode were investigated systematically. Morphology studies showed that sphere-like ethylene–propylene–diene terpolymer particles were dispersed evenly in the etched thermoplastic vulcanizate surface with diameter of 5–7 µm. The results showed that thermoplastic vulcanizate demonstrated characteristic features (hysteresis of energy, residual deformation accumulation, stress softening) of Mullins effect. Compared with that of ethylene–propylene–diene terpolymer/carbon black vulcanizate, the polypropylene/ethylene–propylene–diene terpolymer thermoplastic vulcanizate had much higher stress and its stress softening phenomenon was more obvious. The reversibility of Mullins effect showed a temperature-dependent feature and was enhanced with increasing temperature. [ABSTRACT FROM PUBLISHER]

This work focuses on the optimization and identification of blend with balanced mechanical properties of Co-PP/EPDM. The blending factors include time, temperature, screw speed, and blend ratio. Tensile strength and elongation at break were studied as the two responses. D-Optimal model was used to fit the regression line, which was validated using analysis of variance and “lack of fit” test. An average error of 10% (for tensile strength) and 3.2% (for elongation at break) was observed between the actual and predicted values. Further, the thermal stability, dynamic mechanical analysis, and phase morphology of the optimized blend were also investigated. [ABSTRACT FROM AUTHOR]

O-rings are the most common type of seal used in industry due to their robustness, versatility and low cost. Some specifications specify elastomeric property testing on platens [sheets]. However, the end users typically receive only the end item or final part [O-rings], which needs to be tested for incoming, receiving inspection purposes. This paper investigates issues related to performing hardness and compression set measurements on O-rings. Measurements made on O-rings are compared to those made on platens to explore the effect of shape factor for testing. The effects of measurement variability, test specimen type, elastomer type and formulation are discussed. [ABSTRACT FROM AUTHOR]

In the present investigation, ethylene propylene diene monomer (EPDM) rubber/high density polyethylene (HDPE) (100/50) blend has been loaded with varying contents of high abrasion furnace (HAF) carbon black as reinforcing filler. Its range is between 20 wt% and 80 wt% of the rubber. Vulcanization of prepared composites has been induced by ionizing radiation of accelerated electron beam for varying doses up to 250 kGy. Thermogravimeteric analysis and electrical conductivity were also followed up. The data obtained indicate improvement in mechanical, physical, electrical and thermal properties. [ABSTRACT FROM AUTHOR]

Clay and ultraviolet irradiation treated PTFE filled clay/EPDM/PTFE composites were prepared. Results show that the tensile strength increase with the irradiation time, and the tribological properties of the ultraviolet irradiation treated PTFE filled clay/EPDM/PTFE composites are superior to those of clay/EPDM/PTFE composites in terms of the crosslink between the reinforcing particle and matrix. This may be due to the nanoscale effects, and the strong interaction force existed between the matrix and the clay interface. [ABSTRACT FROM AUTHOR]

The mechanical properties and flame retardancy of linear low-density polyethylene/ethylene-propylene-diene terpolymer thermoplastic elastomers (TPEs) containing magnesium hydroxide sulfate hydrate (MHSH) whiskers and their corresponding un-vulcanized blends (UVBs) were evaluated using static tensile measurements, cone calorimetry and limiting oxygen index (LOI) tests. TPEs exhibited better fire-resistant properties in reducing peak heat release rate and improving LOI values to UVBs. Scanning electron microscopy (SEM) images showed that TPE sample left a more compact char after cone test. Results from tensile tests confirmed that TPEs had superior mechanical properties to UVBs due to the better compatibility between MHSH whiskers and polymer matrix. [ABSTRACT FROM PUBLISHER]

Bentonite (Bt) with irregular shape and surface morphology was used as a new type of filler in EPDM. EPDM/Bt composites were prepared using a laboratory size two-roll mill by adding 0 to 70 phr Bt. The effects of Bt loading on curing characteristics, morphology, tensile and thermal properties of EPDM/Bt composite were studied. Scorch and curing time were decreased with 0 to 30 phr loading and increased subsequently at 50 and 70 phr. Tensile strength and elongation at break (Eb) were increased with increasing Bt loading from 0 to 50 phr and decreased at 70 phr, whereas the tensile modulus (M100%) shows an increasing trend with increasing Bt loading. Thermogravimetric analysis shows the enhancements of thermal properties with increasing Bt loading. Morphological studies of tensile fracture surfaces of EPDM/Bt composite proves good interaction between Bt particles and EPDM at 50 phr and formation of Bt agglomerates at 70 phr. [ABSTRACT FROM AUTHOR]

The PDP, a novel intumescent flame retardant (IFR) with high charred residue of 40.8% in N2 at 700°C by TGA was synthesized successfully for preparing halogen-free flame-retardant EPDM composites. The UL-94 V-0 rating was achieved for EPDM composites with 20 phrs carbon black at the same time by using only 60 phrs PDP. In situ FTIR spectroscopy reveals that P-N rich charred residues are formed through the interaction between hydrogen atom in weak base of P-NH-C and phosphate. SEM characterizes the formation of intumescent chars during burning. The mechanical properties of composites are also discussed. [ABSTRACT FROM AUTHOR]

New halogen-free, magnesium hydroxide (MH) flame retarded ethylene propylene diene terpolymer (EPDM) composites have been prepared via melt blending method, using lanthanum oxide (La2O3) as a synergistic agent. Influence of La2O3 on the flame method retardancy and thermal stability of the flame retarded EPDM composites are investigated by limiting oxygen index (LOI), UL94 testing, cone calorimeter and thermogravimetric analysis (TG), respectively. Moreover, the morphology of the char residues of the composites after cone calorimeter testing is characterized by scanning electron microscopy (SEM). The thermal aging stability of the composites is evaluated via the test of mechanical properties. Results show that La2O3 plays a positive role in improving the flame retardancy and thermal stability of the composites. [ABSTRACT FROM AUTHOR]

This paper discusses process development, tensile properties, morphology, oil resistance, gel content, and thermal properties of polypropylene (PP)/ethylene-propylene diene terpolymer (EPDM)/natural rubber (NR) vulcanized blends with the addition of N,N-m-phenylenebismaleimide (HVA-2) as a compatibilizer. Blends were prepared in several blend ratios in a Haake Polydrive with temperature and rotor speed of 180°C and 50 rpm, respectively. Results indicated that the combination of dicumyl peroxide (Dicup) with HVA-2 shows high torque development and stabilization torque as compared to the blend with Dicup vulcanization alone. In terms of tensile properties, the combination of Dicup with HVA-2 shows higher tensile strength, tensile modulus (M100), elongation at break, oil resistance, and gel content in all blend ratios compared to similar vulcanized blends with Dicup without HVA-2 addition. Scanning electron microscope (SEM) micrographs of the blends support that the cross-linking and compatibilization occur during the process of the vulcanized blend containing HVA-2. In the case of crystallinity of the blends, the addition of HVA-2 in Dicup vulcanized blend revealed a tendency for the percentage of crystallinity (Xc) to decrease. The addition of HVA-2 in Dicup vulcanization also produced blends with good thermal stability dealing with the so-called coagent bridge formation. [ABSTRACT FROM AUTHOR]

Reactive blends of ethylene propylene diene monomer (EPDM) and polyamide (PA) 66 were prepared in the single screw and twin screw extruder using maleic anhydride as coupling agent and dicumyl peroxide (DCP) as initiator. The optimum concentration of DCP for grafting maleic anhydride on EPDM was determined. The grafting efficiency was determined by Fourier transform infrared (FTIR) spectroscopy, and (DMTA) tests were conducted to determine the damping, loss, and storage modulus of PA 66 composites. A capillary rheometer and parallel plate rheometer were employed to characterize the rheological properties at high and low shear rates. It was seen that the glass fibers are not long and continuous, and they act as fillers, therefore reducing the damping in the composite. No significant change was observed in the glass transition temperature of the blend as compared with the individual components, especially PA 66. In malienated EPDM blends with increasing EPDM from 10 to 15%, the height of glass transition temperature peak increases. Capillary rheometer tests show that for all samples the apparent viscosity decreases with increasing shear rate, which is a characteristic of a non-Newtonian pseudo plastic fluid. The viscosity ration of malienated EPDM and PA 66 shows a considerable difference between them and only at higher shear rates do the viscosities get closer. [ABSTRACT FROM AUTHOR]

New halogen-free, flame-retardant ethylene propylene diene terpolymer (EPDM)/organically modified magnesium hydroxide (MH) composites have been prepared via melt compounding method, using maleic anhydride grafted ethylene-vinyl acetate copolymer (MAH-g-EVA) as a compatibilizer. Influence of MAH-g-EVA on the fire and thermal properties of the composites are investigated by means of LOI, UL94 vertical burning, cone calorimeter tests, thermogravimetric analysis (TGA), real time fourier-transform infrared spectroscopy (RTFTIR) and environmental scanning electron microscopy (ESEM). The results show that MAH-g-EVA plays a positive role in improving the flame retardancy and thermal stability of the composites. [ABSTRACT FROM AUTHOR]

Ethylene propylene dine monomer (EPDM) was blended with both ground tire rubber (GTR) and high-density polyethylene (HDPE) prepared at different ratios and then exposed to gamma and ultraviolet radiations. The mechanical, physical, and thermal properties were investigated with respect to the kind of irradiation and blend compositions. A scanning electron microscope was also used to examine the morphology of the irradiated blends. The blend of ratios (75/25/50) exhibited the best mechanical and physical properties after gamma irradiation, so this blend was taken as an example to be exposed to the UV radiation. The results indicated an improvement in the mechanical and physical properties for the blends exposed to gamma irradiation, but the mechanical and physical properties examined after UV irradiation were slightly affected. Scanning electron microscope measurements indicated the improvement in the homogeneity and the compatibility after irradiation, particularly in case of gamma radiation. [ABSTRACT FROM AUTHOR]

Comparative studies on the effect of aluminium particles in natural rubber (NR) and ethylene-propylene-diene terpolymer (EPDM) were conducted. The incorporation of aluminium particles in NR or EPDM composites increased the cure time, t90, and scorch time, tS2. At a fixed filler loading, EPDM composites exhibited longer t90 and tS2 than NR composites. The results also indicate that the maximum torque, MH of aluminium filled NR and EPDM composites increase with increasing filler loading. For tensile properties, EPDM composites show lower tensile properties than NR composites. Thermogravimetric analysis (TGA) results show that aluminium filled EPDM composites have better thermal stability than aluminium filled NR composites. The results for electrical properties indicate that the electrical properties of aluminium filled NR and EPDM composites increase with increase in filler loading. [ABSTRACT FROM AUTHOR]

A method of chemical modification in situ of ethylene-propylene-diene rubber (EPDM) filled with carbon black was studied. A bifunctional monomer, glycidyl methacrylate (GMA), was used as the modifier to improve the dispersibility of carbon black in the rubber and to enhance the mechanical properties of EPDM vulcanizates. The effects of GMA on the structure and properties of EPDM vulcanizates such as determination of cross-linking density and vulcanizing properties as well as mechanical properties were investigated by FT-IR, SEM, and DMTA. The results showed the addition of GMA into carbon black filled EPDM compounds could remarkably improve the mechanical properties of the vulcanizates. The optimum content of GMA was about 5.0 phr when the content of carbon black was 50 phr. The reason for improvement of the mechanical properties might be attributed to the chemical combinations between rubber macromolecular chains and carbon black surfaces by GMA. The action of GMA was similar to a cocuring agent and a coupling agent. [ABSTRACT FROM AUTHOR]

The effects of vibration force field on mechanical properties of blends of EPDM/PP during process of plastics in tri-screw dynamic mixing extruders were investigated experimentally. It was found that vibration force field enhanced mechanical properties of blends of EPDM/PP, and the amplitude of enhancement varied as EPDM content varying. The yangs modulus, the impact strength and the tensile strength were improved the maximum 17, 28, and 17.3%, respectively under dynamic conditions than that under steady conditions. Mechanical properties of blends of EPDM/PP represented a tendency of a rising followed by a fall with the increase of vibration frequency and amplitude. [ABSTRACT FROM AUTHOR]

Organoclay was compounded with ethylene-propylene-diene-monomer (EPDM) using a two roll mill and cured by conventional sulfur curing system. The organoclay content was progressively increased from 0 to 10 parts per hundred of rubber (phr) of the EPDM rubber. Cure characteristics were carried out on an Ekktron moving die rheometer. It has been found that cure and scorch time were decreased with organoclay loading. On the other hand, minimum and maximum torque has been increased with organoclay loading as well. The observed trend was related mainly to the strong interaction between the rubber matrix and the nanoscaled filler (organoclay in this case) and subsequently to the improved cross-link density. Such improvement was attributed to the small size of the filler particles and to the amine functionality in the organoclay structure. Thermal analysis obtained from differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) revealed that, the enthalpy of vulcanization increased with organoclay content indicating increased cross-link density formation, whereas TGA analysis showed that organoclay has increased the thermal stability of the EPDM hybrids. [ABSTRACT FROM AUTHOR]

In this research, the effects of formulation and the amount of triallyl cyanorate (TAC) as coupling agent on peroxide vulcanization and mechanical properties of the participated silica filled EPDM elastomer are investigated. The results of curing process and measuring mechanical properties (hardness, modulus, tensile strength, elongation at break, abrasion, resilience) of compounds show that silica accounts for mechanical properties improvement and TAC decreases Mooney viscosity and scorch time and also increases optimum curing time; therefore, it prevents compound scorching. In addition, results show that TAC improved rubber-filler interaction and apparent crosslink density, which reflected on mechanical properties under study and SEM photographs. [ABSTRACT FROM AUTHOR]

Butadiene-acrylonitrile rubber (NBR) was blended with ethylene- propylene-diene rubber (EPDM) in the presence and absence of different amounts of bromobutyl rubber (BIIR) to be tested as a compatibilizer. The results revealed that 10 phr was the optimum amount of BIIR to get a compatible blend. Dicumyl peroxide (DCP) curing system resulted in EPDM/NBR vulcanizates with better thermal aging resistance than did sulfur vulcanizates. Also DCP produced vulcanizates with the most reduced swelling values both in motor oil and brake fluid. On the other hand, sulfur-curing systems produced EPDM/NBR vulcanizates with much higher mechanical properties than did DCP vulcanizates. The fatigue resistance of the vulcanizates was greatly improved upon blending the two types of rubber. Also, the 25/75 EPDM/NBR blend possessed the highest aged mechanical properties together with good thermal stability. [ABSTRACT FROM AUTHOR]