Ethylene Propylene Diene Terpolymer Research Articles

Crystallization Kinetics for PP/EPDM/Nano-CaCO3 Composites – The Influence of Nanoparticles Distribution

Abstract The primary aim of this paper is to provide an insight on the effect of the distribution of calcium carbonate nanoparticles (nano-CaCO3) on the isothermal crystallization kinetics in Polypropylene (PP)/ethylene-propylene-diene terpolymer (EPDM)/nano-CaCO3 composites prepared by different compounding procedures. PP/EPDM/CaCO3 composites were prepared by two compounding procedures (direct compounding: mixed all three solid materials together; multistep compounding: the melted EPDM/CaCO3 master batch in a single screw extruder blended with melted PP in twin-screw extruder via injecting into the twin-screw extruder from a lateral port at the melting section of the twin-screw extruder). Morphological observation showed that abundant CaCO3 particles concentrated around EPDM dispersed phase in the multistep compounding composite, essentially different from the respectively dispersed morphology of CaCO3 particles and EPDM domains in the matrix for the direct compounding composite. Moreover, better dispersion of CaCO3 particles in the multistep compounding composite was observed comparing to the direct compounding composite. Futhermore, a pronounced improvement of the crystallization half time (t1/2), rate of crystallization (G) was achieved in the multistep compounding composite, which may originate from the better dispersion of CaCO3 particles providing larger nucleation density and the collaborative nucleation of EPDM and CaCO3 during the isothermal crystallization.

Hyperelastic model analysis of stress-strain behavior in polybutadiene/ethylene-propylene diene terpolymer nanocomposites

Micromechanics of elastomer nanocomposite samples based on polybutadiene (BR), ethylene-propylene diene terpolymer (EPDM) hyperelastic matrixes prepared via melt compounding was investigated using uniaxial tensile analysis. Constitutive hyperelastic models, including Polynomial, Yeoh, Ogden, Arruda-Boyce, and Van der Waals were used to determine material parameters in incompressible isotropic elastic strain-energy functions on the basis of a nonlinear least squares optimization method by fitting the data obtained from uniaxial classic experiments. Effect of nanoclay (0, 3, 5, 7, and 10 phr) content on the simulation accuracy was investigated. Simulation results compared with the experimental data suggested that the Ogden model as the most consistent model investigated here. J. VINYL ADDIT. TECHNOL., 2015. © 2015 Society of Plastics Engineers

Effects of blend composition and compatibilization on the melt rheology and phase morphology of binary and ternary PP/PA6/EPDM blends

Ternary blends based on isotactic polypropylene (iPP) modified by polyamide 6 (PA6) and ethylene–propylene–diene terpolymer (EPDM) were prepared and their rheological properties were studied. The total content of dispersed phases was kept fixed at 30 wt%. The goal was to investigate the effect of blend composition and compatibilization process using PP-g-MA on the dynamic viscoelastic properties of PP/PA6/EPDM ternary systems. Then, attempts were made to correlate the viscoelastic response of the blends with their morphological texture as examined by SEM technique. Different rheological behaviors were observed depending on the dispersed phase(s) type, concentration and alteration of interfacial interaction between the phases. In the blends containing PA6 phase, compatibilization process led to a significant change in the morphology of the blend with a subsequent change in the viscoelastic properties, especially at low-frequency regions. Rheological analysis revealed a deviation from liquid-like behavior for certain binary and ternary systems which were dependent on the PA6 and EPDM contents and the microstructure of the blends as well. In the case of ternary blends, separated-type morphology was observed in consistent with morphology predicted by spreading coefficient concept. The relationship between the morphology and relaxation process of the individual particles was also discussed.

EPDM composite membranes modified with cerium doped lead zirconate titanate

Abstract This study was performed on γ -irradiated ethylene-propylene diene terpolymer (EPDM) loaded with lead zirconate titanate. The inorganic phase has a perovskite structure with general formula Pb(Zr 0.65− x Ce x Ti 0.35 )O 3 . The three composites with different Ce dopant concentrations revealed the stabilization activity of filler against oxidation proved by chemiluminescence investigation in respect to pristine polymer. The presence of cerium low concentrations in the solid lead zirconate titanate nanoparticles causes significant slowing of oxidation rate during radiation exposure. The improvement in the stabilization feature of filler is correlated with the existence of traps, whose interaction with free radicals assumes medium energy due to their convenient depth.

Effect of borax on the thermal and mechanical properties of ethylene‐propylene‐diene terpolymer rubber‐based heat insulator

ABSTRACTThe effect of Borax on the mechanical and ablation properties of three different ethylene‐propylene‐diene terpolymer (EPDM) compounds containing 20 phr carbon fiber, 20 phr Kevlar or 10 phr/ 10 phr carbon fiber/ Kevlar was investigated. All formulations contained 30 phr fumed silica powder and 10 phr paraffinic oil. It was found that adding Borax to the composite samples containing carbon fiber or Kevlar fiber or their mixture with an equal ratio can increase the tensile strength, elastic modulus and hardness with a slightly decrease in the elongation at break of the rubber samples. The results of thermogravimetry analysis (TGA) on the various samples showed significant increase in the char yield at 670°C by adding Borax to the rubber compounds. Moreover, ablation resistance of samples was also improved by increasing Borax content. Meanwhile, density and thermal conductivity of the insulator were also reduced up to about 10% when the carbon fiber was replaced with the Borax. The results indicated that composites containing Kevlar have high storage modulus and produce compact and stable char. EPDM rubber composite containing Borax (20 phr), carbon fiber (10 phr), and Kevlar (10 phr) showed thermal and ablative properties comparable with those of the asbestos‐ filled EPDM. The thermal conductivity and ablation rate of the above‐ mentioned sample were 0.287 W/m/K and 0.13 mm/s respectively. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci.2015,132, 41936.

Compatibilization by Olefin Block Copolymer (OBC) in Polypropylene/Ethylene-Propylene-Diene Terpolymer (PP/EPDM) Blends

The compatibilization by olefin block copolymer (OBC) in the blends of polypropylene (PP)/ethylene-propylene-diene terpolymer (EPDM) and the phase morphology of the ternary blends were investigated by rheology, scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) measurements. It was found that the PP/EPDM blends exhibited enhanced mechanical properties in the presence of OBC. The addition of OBC had a significant influence on the phase separation behavior of the blends. For the PP/EPDM-50/50 heterogeneous blends, the addition of 15 phr OBC enabled the two-phase morphology to change from a droplet-matrix structure to a co-continuous one. In the temperature range of 150 to 200 °C, OBC was shown to have a better compatibility with PP than EPDM. The changes in viscosity ratio of the dispersed phase to matrix phase caused by adding OBC might be the dominant factor in controlling the coalescence of the dispersed phase domains. For the crystallization behavior of PP/EPDM/OBC ternary blends, OBC was found to have an induction effect on the formation of β-crystals of PP that was not proportional to the volume of OBC addition. In addition, DSC results showed that PP could induce the OBC crystallization and improve the crystallization temperature of OBC. The existence of simultaneous crystallization behavior between PP and OBC was also observed. A possible mechanism of phase evolution induced by crystallization was proposed.

Structure-Property Relationship in Terms of Dynamic Mechanical Properties of High Energy Radiation Treated Industrially Important Thermoplastic Elastomer Blend

A series of low-density polyethylene (LDPE)/ethylene propylene diene terpolymer (EPDM) blends with various compositions have been prepared by melt mixing followed by injection molding. These specimens are irradiated at 40, 80, 120 and 160 kGy electron beam radiation. The gel content increases with increase in EPDM and as well as EB dose. Storage modulus (E’) and loss modulus (E”) are decreased with increase in EPDM content. Storage modulus continues to increase and loss modulus keeps on decreasing with radiation dose. Interestingly, damping property is found to be more for EPDM rich blends, which again decreases upon irradiation. Morphology of fractured surface of LDPE/EPDM shows that with increase in EPDM content, the size and depth of the cavity becomes larger and deeper indicating higher ductility. But, EB crosslinking makes the surface smoother and the smoothness keeps on increasing with increase in dose rendering stiffness to the samples.

Effect of annealing temperature on low-temperature toughness of β-nucleated polypropylene random copolymer/ethylene-propylene-diene terpolymer blends

In this study, the effect of annealing temperature on the impact toughness of β-nucleated polypropylene random copolymer (PPR) and ethylene-propylene-diene terpolymer (EPDM) blends was investigated by differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), dynamic mechanical analysis (DMA) and scanning electron microscopy (SEM). Interestingly, the impact strength of β-PPR/20EPDM blend annealed at 120 °C is 1.8 times as high as that of unannealed samples. In addition, the crystalline structure, the relaxation of chain segments and fracture morphology of β-PPR/EPDM blends were also investigated to explore the toughening mechanism related to annealing. The results show that annealing at moderate temperatures results in the improvement of integrity of the crystal structure and the relative content of β-phase. The work provides a possible method to toughen the semicrystalline polymer at low temperatures by annealing.

Long-term performance of EPDM geomembrane in El Boquerón reservoir

ABSTRACT: El Boquerón reservoir (Canary Islands, northern hemisphere) is waterproofed with an ethylene-propylene-diene terpolymer (EPDM) geomembrane (GM). To evaluate the durability of EPDM GMs in hydraulic applications, the characteristics of the EPDM GM (resin and additives) installed in the El Boquerón reservoir were followed for over 21 years. The results of this study are presented herein and show that, based on measurements of specimens from the north and south slopes of the reservoir, the orientation of the GM influences its ageing, with the north slope in the coronation or crest area ageing the most rapidly. Over the years, the El Boquerón EPDM GM oxidised, which may be the main cause of crosslinking in the EPDM. In turn, crosslinking could be the mechanism behind some of changes observed in the EPDM GM characteristics over time. In addition, some of the mechanical characteristics of the EPDM GM were influenced by the additives in the formulation; in particular, the loss and oxidation of paraffinic oils. However, despite the age-induced evolution of the mechanical and physicochemical characteristics of the GM, the El Boquerón EPDM GM, after 21 years of exposure, still satisfies the minimum requirements established by French standards for virgin GMs.

CARBON NANOFIBER COMPOSITE WITH EPDM AND POLYIMIDE FOR HIGH-TEMPERATURE INSULATION

ABSTRACT Elastomers and their composites are extensively used as a thermal insulation system in heat treatment, power generation, fire protection, and aerospace. Among different elastomers, low-density ethylene propylene diene terpolymer (EPDM) has interesting properties, such as excellent resistance to aging and oxidative degradation due to its saturated back bone. Furthermore, introduction of polyimide (PI) to the base elastomer increases its thermal stability. On the other hand, carbon nanofiber (CNF) reinforces the matrix to enhance the mechanical properties with an additional advantage of better char yield. To achieve better rubber-filler compatibilization, modification of EPDM was carried out by grafting with maleic anhydride (MAH). Morphological studies by scanning electron microscopy and high-resolution transmission electron microscopy exhibited uniform dispersion of nanofillers throughout MAH grafted EPDM matrix. Thermal properties of the EPDM/PI nanocomposites were characterized by thermogravimetric analysis and differential scanning calorimetry. Besides these, thermal conductivity, thermal diffusivity, and specific heat were also measured. PI- and CNF-filled maleated EPDM composites showed very good physical and thermomechanical properties for high-temperature insulation compound.

Correlation of crosslink densities using solid state NMR and conventional techniques in peroxide-crosslinked EPDM rubber

Peroxide-crosslinked ethylene propylene diene terpolymer (EPDM) elastomer samples were prepared with various types and concentrations of peroxide, with and without co-agent. The variation of crosslink density, the spatial distribution of the crosslinks in the network and the presence of network defects in EPDM rubber were investigated on a molecular level using proton low-field solid-state double-quantum (DQ) NMR spectroscopy. The results reveal that types and concentrations of peroxides do not affect the overall rather inhomogeneous spatial distribution of the crosslinks, but do affect significantly the average crosslink density. The introduction of a co-agent leads to higher crosslink densities and increased levels of spatial crosslinking inhomogeneity as well as non-elastic defects. Apparent crosslink densities as measured by DQ NMR, solvent swelling, linear and non-linear stress-strain measurements (Mooney–Rivlin analysis), and the curemeter, are correlated and discussed. While most of the results can be interpreted consistently and in agreement with the usual assumptions concerning the effect of (trapped) entanglements, a previously unnoticed, decisively non-linear correlation of the NMR results with the linear-regime modulus indicates a large influence of the substantial crosslinking inhomogeneities on the mechanical behaviour. Also, the data suggest a rather efficient trapping of entanglements, possibly because of reduced chain slippage due to the bulky norbornene comonomers.

Synthesis of EPDM-g-MAN by suspension graft copolymerization and its toughening effect on SAN resin

Suspension graft copolymerization of methyl methacrylate and acrylonitrile onto ethylene–propylene–diene terpolymer (EPDM) was carried out under different reaction conditions. A series of graft products of EPDM-graft-methyl methacrylate and acrylonitrile (EPDM-g-MAN), characterized by Fourier-transform infrared spectroscopy, was blended separately with styrene–acrylonitrile (SAN) resin to investigate their toughening effect on SAN matrix. The relationship between the polarity of EPDM-g-MAN and toughness of EPDM-g-MAN/SAN resin blends (AEMS) was evaluated. The compatibility and morphologies of AEMS were probed by dynamic mechanical analysis, transmission electron microscopy, and scanning electron microscopy to determine the toughing mechanism of the blends. Thermogravimetry results showed that the thermal stability of AEMS was enhanced with the incorporation of EPDM-g-MAN graft copolymer.

DEVELOPMENT OF AN ECO-EFFICIENT PRODUCT/PROCESS FOR THE VULCANISING INDUSTRY

This paper presents the development of an eco-efficient product/process, which has improved mechanical properties from the introduction of natural fibres in the EPDM (Ethylene-Propylene-Diene-Terpolymer) rubber formulation. The optimisation analysis is made by a fractional factorial design 2 11-7 . Different formulations were evaluated using a multi-response desirability function, with the aim of finding efficient levels for the manufacturing time-cycle, improving the mechanical properties of the product, and reducing the raw material costs. The development of an eco-efficient product/process generates a sustainable alternative to conventional manufacturing.

Influence of reaction parameters on the structure of in situ rubber/silica compounds synthesized via sol–gel reaction

ABSTRACTIn situ silica was synthesized in three non‐vulcanized rubber matrices, namely natural rubber, styrene‐butadiene rubber, and EPDM (ethylene‐propylene diene ter‐polymer), using the sol–gel method with tetra‐ethoxysilane (TEOS) as silica precursor and hexylamine as catalyst. The effect of the reaction parameters such as the amount of TEOS, the reaction time (15–120 min), and the type of rubber was explored. Transmission electron microscopy was used to study the gradient in silica content and particle size over the sample thickness. The diffusion gradient of TEOS and catalyst solution in the rubber matrix responsible for the gradient was studied with Fick's law. An excellent dispersion of silica was obtained for all rubbers, even for the very non‐polar EPDM, without the use of any additives to improve the dispersion. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014, 52, 967–978

Synergistic Effect of Expanded Graphite/Carbon Black on the Physical and Thermo-Mechanical Properties of Ethylene Propylene Diene Terpolymer

The present research work explored the effect of expanded graphite (EG) and modified EG (MEG) with and without carbon black (CB) on the mechanical, dynamic mechanical, thermal etc. properties of ethylene propylene diene terpolymer (EPDM). EG-and MEG-filled EPDM nanocomposites were fabricated in the presence and absence of CB by direct mixing on an open two roll mill. The microstructure of the EPDM-based nanocomposites was investigated by wide angle X-ray diffraction (WAXD) and high-resolution transmission electron microscopic (HR-TEM) analyses. EG- and MEG-loaded EPDM nanocomposites in the presence and absence of CB exhibited improved mechanical, dynamic mechanical properties and thermal stability.

Influence of ethylene–propylene–diene terpolymer addition on processing parameters, phase structure and thermal behaviour of polypropylene/low-density polyethylene blends

The influence of blend composition and ethylene–propylene–diene terpolymer (EPDM) content on the processing parameters, phase structure and thermal behaviour of polypropylene (PP) and low-density polyethylene (LDPE) blends was studied. Processing parameters of blends in twin-screw extruder were followed by output ( Q), torque (TQ) and back pressure ( p), and apparent viscosity as given by TQ/ Q and p/ Q ratios, while the thermal behaviour was measured using differential scanning calorimetry. Phase structure was investigated using scanning transmission electron microscopy (STEM). The degree of crystallinity ( χc) of PP phase decreased and χc of LDPE phase increased with higher LDPE content in blends with and without EPDM. STEM micrographs of EPDM compatibilized PP/LDPE blends of compositions 80/20 and 20/80 showed particulate morphology, whereas in the blends of compositions 60/40 and 40/60 the morphology was co-continuous. The EPDM compatibilizer was localized on the interface.

Toughening Effect of Ethylene Propylene DieneTerpolymer-Graft-Styrene-Acrylonitrile Copolymer (EPDM-g-SAN) on SAN Resin

The reaction product EPDM-g-SAN, synthesized by suspension graft copolymerization of styrene (St) and acrylonitrile (AN) in the presence of ethylene-propylene-diene terpolymer (EPDM), was blended with a commercial styrene-acrylonitrile copolymer (SAN resin) to prepare AES blends with high impact strength. The effects of AN mass percentage in the St-AN comonomer mixture (f AN), EPDM mass percentage in the feed of EPDM and St-AN (f EPDM) and reaction time on monomer conversion ratio (CR), grafting ratio (GR), and AES notched Izod impact strength were characterized. The notched Izod impact strength of AES containing 15 wt% EPDM reached its maximum with f AN of 40 wt% and f EPDM of 45 wt%; this was attributed to the polarity of the SAN copolymer obtained being appropriate with that of the SAN resin matrix. The dependences of GR and the notched Izod impact strength of AES containing 25 wt% EPDM on the reaction time were in rough agreement. The effect of EPDM content on the AES notched Izod impact strength indicated that the brittle-ductile transition of AES occurred for an EPDM content from 12.5 to 15 wt%. TEM and SEM analysis showed that the phase structure of AES exhibited a “salami” like structure, and the toughening mechanism of AES was shear yielding of the SAN resin matrix, which endowed AES with excellent toughness.

EPDM/silicone blend layered silicate nanocomposite by solution intercalation method: Morphology and properties

Ethylene–propylene–diene terpolymer (EPDM)/silicone blend nanocomposites are prepared by solution method for the first time. EPDM and silicone rubber in their 50:50 (by weight) blend is intercalated within the silicate sheets of organically modified montmorillonite. Organic modification to the pristine sodium montmorillonite (Na‐MMT) surfaces is carried out by ion‐exchange reaction using hexadecyl ammonium chloride. The incorporation of such organic functional group makes Na‐MMT hydrophobic and expands the interlayer spacing between silicate sheets. The intercalated structure of EPDM/silicone blend nanocomposites is characterized by the X‐ray diffraction. Transmission electron microscopic characterization visualized the presence of both exfoliated and intercalated layered silicate in the polymer nanocomposites. The mechanical properties of the nanocomposites show a maximum improvement in tensile strength and elongation at break of 23 and 68%, respectively, compared with EPDM/silicone blend. The dielectric measurement demonstrates the increase in relative permittivity for the nanocomposite than the pure blend. The increase in the onset temperature of the thermal degradation of nanocomposites (∼52°C) corresponding to 1 wt% decomposition indicates the enhancement of thermal stability of (EPDM)/silicone blend due to interaction with silicates. POLYM. COMPOS., 35:1834–1841, 2014. © 2014 Society of Plastics Engineers

Mechanical properties, morphology, and Mullins effect of thermoplastic elastomers based on polypropylene and waste ethylene–propylene–diene terpolymer powder compatibilized by styrene–butadiene–styrene block copolymer

Thermoplastic elastomers (TPEs) based on polypropylene (PP)/waste ethylene–propylene–diene terpolymer powder (WEPDMP) composites were prepared by melt compounding, and the composites were compatibilized by styrene–butadiene–styrene block copolymer (SBS). The effects of SBS compatibilizer on mechanical, morphological properties, and the Mullins effect of the TPEs were investigated systematically. Experimental results indicate that SBS had a good compatibilization effect on the PP/WEPDMP composites. Compared with PP/WEPDMP composites, the tensile strength and the elongation at break went through a maximum value at an SBS content of 6 phr, which were improved by 49.4 and 170.3%, respectively. Morphology study shows that the interface interaction of the PP/WEPDMP composites compatibilized by SBS was strong, which contributed to the significantly improved mechanical properties. Mullins effect results show that the softening obviously appeared after the second loading–unloading cycle, while the maximum stress decreased slightly at the later cycles and the internal friction loss of PP/SBS/WEPDMP composites was lower than that of PP/WEPDMP composites, indicating the elasticity of PP/WEPDMP TPE is improved by the incorporation of SBS.

Reaction mechanism of suspension graft copolymerization of styrene and acrylonitrile in the presence of ethylene propylene diene terpolymer

A sequential synthesis of ethylene propylene diene terpolymer-g-poly (styrene-co-acrylonitrile) (EPDM-g-SAN) graft copolymers was carried out via suspension graft copolymerization using benzoyl peroxide (BPO) as an initiator. After the synthesis, the final product was separated by Soxhlet extraction to obtain the styrene-acrylonitrile free copolymer (SANf), non-grafted EPDM and EPDM-g-SAN, which were subsequently characterized by 1H-NMR and FTIR analyses to verify their purity. The dependence of the reaction behaviors on the reaction time was systematically investigated. When the reaction time was varied from 20 min to 100 min, the GPC analysis of the obtained SANf showed a bimodal profile, due to the co-existence of SANL and SANH free copolymers, of low and high molecular weights, which were respectively formed by chain transfer termination and bi-radical termination of the free polymeric radicals. These results revealed that the graft site initiation was dominated by free polymeric radicals attacking the EPDM backbones at the beginning of the grafting process, accompanied by non-grafting copolymerization reactions. On the other hand, the GPC analysis of non-grafted EPDM and EPDM-g-SAN revealed that the reaction mechanism also involved the chain scission of the EPDM molecules which were partly incorporated into the backbone of EPDM-g-SAN and the incorporation of SANf into the grafted chains (g-SAN), resulting in added grafted EPDM and grafting ratio. Furthermore, a novel and effective method was developed to determine the number of g-SAN, and thus the number-average molecular weight of g-SAN was estimated.