Propylene Diene Monomer Research Articles

Use of Differential Scanning Calorimetry (DSC) in the Characterization of EPDM/PP Blends

New polyolefinic thermoplastic elastomers based on the ethylene–propylene-diene monomer (EPDM) and polypropylene (PP) containing an EPDM elastomer of the last generation (Nordel NDR 47130), obtained by polymerization in the gaseous phase with metallocene catalysis, were prepared and characterized. The melting and crystallization behavior of these blends was investigated by differential scanning calorimetry. It is observed that the melting temperature, crystallization temperature, and crystallinity degree increase with an increase of PP loading. The influence of the blend composition on the physico-mechanical characteristics was discussed using statistical processing of the experimental data. Two compatibilizing procedures were utilized to improve the physico-mechanical characteristics of the samples: an addition method using different compatibilizing agents and dynamical vulcanization with three types of crosslinking systems. Significant improvements of the tensile strength and tear strength were noted by dynamic crosslinking, and the best results were obtained using a crosslinking system based on phenolic resin and tin chloride.

Aging behavior and mechanism of ethylene–propylene-diene monomer (EPDM) rubber in fluorescent UV/condensation weathering environment

Ethylene–propylene-diene monomer (EPDM) rubber was exposed to an artificial weathering environment produced by fluorescent UV/condensation weathering device for different time periods. The surface chemical changes were detected by X-ray Photoelectron Spectroscopy (XPS) and Raman spectroscopy. The plausible aging mechanism of EPDM was proposed. The surface energy was calculated through contact angles of water and formamide measured by optical contact angle measuring device. The thermal stability was evaluated by thermo-gravimetric analysis (TGA).The results showed that oxygenated species such as C–O–C, C O and O–C O groups were formed in fluorescent UV/condensation weathering environment. EPDM aging occurred from EPDM surface and propagated to EPDM inner body. The surface energy of EPDM increased to a maximum at 36 days of aging and then decreased slowly. Fluorescent UV/condensation weathering environment does not affect the thermal stability of EPDM predominantly.

Adhesion parameters at the interface in nanoparticulate filled polymer systems

AbstractThe interface in particulate filled polymer systems determine to a large extent, the mechanical and morphological properties of composites and polymer blends. The present contribution describes surface free energy measurements and calculations of adhesion parameters at the interface in poly(vinyl acetate) (PVAc) and polyurethane (PU) composites as well as in styrene acrylonitrile/ethylene propylene diene monomer (SAN/EPDM) blends filled with calcium carbonate (CaCO3) nanofillers. The effects that a surface pretreatment of the filler with either silane or stearic acid had on the interface been investigated and related to the resulting properties of the composites and filled polymer blend. The optimal adhesion in the particulate composites and blends was determined by the minimal interfacial energy and optimal coefficient of wetting. The conditions of the optimal adhesion with filler location at the interface, predicting by the thermodynamical models, correlated well with the improvement of the morphological and mechanical properties. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers.

Membrane properties change in fine-pore aeration diffusers: Full-scale variations of transfer efficiency and headloss

Fine-pore diffusers are the most common aeration system in municipal wastewater treatment. Punched polymeric membranes are often used in fine-pore aeration due to their advantageous initial performance. These membranes are subject to fouling and scaling, resulting in increased headloss and reduced oxygen transfer efficiency, both contributing to increased plant energy costs. This paper describes and discusses the change in material properties for polymeric fine-pore diffusers, comparing new and used membranes. Three different diffuser technologies were tested and sample diffusers from two wastewater treatment facilities were analysed. The polymeric membranes analysed in this paper were composed of ethylene–propylene-diene monomer (EPDM), polyurethane, and silicon. Transfer efficiency is usually lower with longer times in operation, as older, dilated orifices produce larger bubbles, which are unfavourable to mass transfer. At the same time, headloss increases with time in operation, since membranes increase in rigidity and hardness, and fouling and scaling phenomena occur at the orifice opening. Change in polymer properties and laboratory test results correlate with the decrease in oxygen transfer efficiency.

Influence of accelerator type on properties of NR/EPDM blends

The effect of accelerator type on processability and mechanical properties of 60/40 natural rubber/ethylene propylene diene monomer (NR/EPDM) blend was investigated. Three groups of commercial accelerators were selected, i.e., sulfenamide group (Santocure-TBBS), thiuram group (Perkacit-TMTD) and mercapto group (Perkacit-MBT and Perkacit-MBTS). The results reveal that the accelerator type not only affects the cure characteristics, but also has great influence on compound viscosity. Among the accelerators studied, TBBS gives the best processing safety together with a relatively high state of cure. In addition, TBBS also provides good cure compatibility between the NR and EPDM phases, giving rise to superior mechanical properties. Although TMTD could give a high state of cure, it causes severe cure incompatibility, leading to poor tensile strength. Due to their lower reactivity, the two mercapto accelerators give a relatively low state of cure. Therefore, the vulcanizates obtained possess low modulus and hardness as well as degree of elasticity. Surprisingly, it is found that the tensile strength of the MBTS-cured blend is relatively high. Good cure compatibility given by MBTS could be used to explain the results.

Evaluation of new conducting polymeric membrane based on sulfonation of compatibilized NR/EPDM blend

AbstractIn this study, research was undertaken to obtain new conducting polymer blend membrane based on compatibilized natural rubber/ethylene–propylene–diene monomer (NR/EPDM) by using different compatibilizers. To utilize them as membranes in polymer electrolyte membrane fuel cells, the blend membranes become conducting by sulfonation reaction, which inserts SO3H groups into the macromolecular chain. The polymer blend membrane ratio (50/50), which was compatibilized by polyacrylonitrile compound was selected among the entire blend studied (A6), with the aim of determining its conductivity and water and methanol permeabilities. The degree of compatibility of NR/EPDM blend was improved by the use of polyacrylonitrile compounds as compatibilizers. The effect of these compounds on the compatibility of blend was evaluated by ultrasonic spectroscopy and differential scanning calorimetry, DSC. It was found that a good compatibility has been achieved by using polyacrylonitrile because of the nitrile groups. When the polymer blend membrane (A6) was sulfonated with SO3H groups good perspectives were shown regarding the methanol and water permeabilities and physical properties comparing to the commercial Nafion one. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3804–3812, 2007

Microstructure of Carbon Filled HDPE/EPDM Composites Studied by Positron Annihilation Spectroscopy

The microstructure of carbon-black (CB) filled high density polyethylene/Ethylene Propylene Diene Monomer (HDPE/EPDM) composite was studied with positron annihilation lifetime spectroscopy (PALS) and positron annihilation Doppler spectroscopy (PADS). It was found that 3 and I3 of the long lifetime component of the PALS spectra show non-linear relations with the EPDM content. It was also noticed the DBS was very sensitive to the microstructural change in the HDPE(CB)/EPDM composites. The spatial distributions of the EPDM and the CB in the polymer are also discussed.

New double negative and positive temperature coefficients of conductive EPDM rubber TiC ceramic composites

In this paper, we have successfully prepared ethylene–propylene-diene monomer (EPDM)/TiC composites as thermistors, with new double negative and positive temperature coefficients of conductivity (NTCC/PTCC). EPDM composites loaded with 50 phr HAF carbon black and different concentrations of TiC were prepared. This study focuses on the effect of TiC content on the vulcanization process, the network structure and the electrical and thermal properties of EPDM/TiC composites. The effect of TiC on the network structure was evaluated e.g. the curing process, the characteristic time constant during vulcanization, the volume fraction of rubber, gel fraction, interparticle distance between conductive particles, the extent of TiC reinforcement in the rubber matrix and molecular weight between cross-linking through experimental and affine–phantom models. The effects of TiC content on the percolation theory, electrical conductivity, conducting mechanism of conductivity, conducting hysteresis and I– V characteristics were also studied, as well as its TiC on the (NTCC/PTCC), thermoelectric power, dielectric constant and thermal conductivity. Stability and reproducibility of the thermal cycles for heating element applications was tested. Specific heat and the amount of heat transfer by radiation and convection as a function of TiC content was calculated using both the calorimetric technique and a theoretical model. It was proved that TiC improves the network structure, electrical and thermal properties of EPDM composites for practical applications.

Process of cure of ethylene–propylenediene monomer rubbers Evaluation of state of cure

The process of cure of ethylene–propylene diene monomer rubbers is described by considering the heat conduction through the mould and through the rubber and also the heat generated by the overall cure reaction. The kinetics of the heat evolved from this cure reaction have been determined by calorimetry by assuming an Arrhenius' law for the temperature dependence as well as the cure enthalpy. The cure enthalpy was found to be proportional to the percentage peroxide within the 2–10% range, while kinetic parameters such as the pre-exponential term and the activation energy did not vary with the percentage peroxide. Thus the state of cure, evaluated on a thermodynamic and kinetic basis, can be obtained at any time and position in the sheet.

Shear Lap-Joint Testing with Rubber Substrate

Abstract A test method has been developed and demonstrated for the determination of shear strength in a lap joint with rubber-like material as a substrate. A testing fixture used a stiffened aluminum substrate with a load-transferring lip, combined with a clamp, that restrained the lateral movement of the rubber. This fixture successfully produced shear-type failures on two back-to-back single lap-joint specimens. The design of the fixture was based on the near-incompressible nature of the rubber materials. The experimental part of the task included two phases: a pathfinder test series; and the actual data generation test series. The former phase involved testing concept development, test fixture design and modification, optimization of test specimen configuration, and failure mode demonstration. This phase was conducted using specimens fabricated in-house by the Mechanics and Materials Technology Center at The Aerospace Corporation. In the second phase, actual shear failure data were generated using specimens that were machined from panels fabricated by the vendor, Elkton Division, Tactical Operations of the Thiokol Corporation. Linear elastic finite element analyses were performed to assist in the optimization of test parameters. The results identified optimal dimensions for lap-joint length, transverse groove width, and bracket lip width for the specimen and fixture configuration. Sixteen tests were done on specimens machined from vendor-supplied carbon phenolic/Epon EA 934 NA/ethylene propylene diene monomer (EPDM) panels. The average failure stresses were 4.46, 3.39, and 3.32 MPa (0.56, 0.43, and 0.42 ksi) for the 7.62, 10.16, and 12.70-mm (0.3, 0.4, and 0.5 in.) long lap-joints. Some of the failures were initiated inside the adhesive whereas other failures occurred between the adhesive and the substrate. This test method should be considered as a viable technique in determining shear strength of bond line with rubber-like material as a substrate. More refinement, however, is needed before an optimal test fixture design can be reached.

Contamination performance of polymeric insulating materials used for outdoor insulation applications

Results of a laboratory evaluation of the contamination performance of silicone rubber and EPDM (ethylene propylenediene monomer) rubber polymers are presented. it is shown that due to significant material differences, these polymers cannot be evaluated using experimental conditions standardized for porcelain and glass. Test conditions which yield good correlation to service experience with polymeric insulators are presented. it is demonstrated that a meaningful contamination test for polymers is a salt-fog test using water at low (250 mu mS/cm) conductivity with the samples being electrically stressed at 40 V/sub rms//mm. Under these conditions it was possible to observe the following, which has been demonstrated by service experience: (a) the leakage current is dependent on the polymer material, (b) silicone rubber resists the continuous water film formation on the surface for a much longer time than EPDM, and (c) more degradation has been observed on EPDM than on silicon rubber.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Thermal Performance of Solar Collectors with EPDM Absorber Plates

An experimental study of flat-plate solar collectors using ethylene, propylenediene monomer (EPDM) absorber plates is descn"bed. In spite of the high thermal resistance of this material the performance is found to compare well with metal absorbers and to be in agreement with the Hottel-Whillier-Bliss equation. There is, however, an observed increase in the heat loss coefficient for mass flow rates below a critical value.

Graft copolymerization of vinyl chloride onto ethylene propylene rubber (EPR) and ethylene propylenediene monomer (EPDM) by bulk process

AbstractVinyl chloride was graft copolymerized on ethylene propylene rubber (EPR) and ethylene propylene diene‐monomer rubber (EPDM) by a bulk process to give a multi‐component end product consisting of three components and two phases. The reaction system forms a pseudo‐emulsion at an early stage of reaction where the phase morphology of graft poly(vinyl chloride) (PVC) is determined. The formation of pseudo‐emulsion was confirmed visually, by the particle size of PVC prepared in the presence of rubber and by the phase morphology of rub be r‐g‐PVC which is similar to that from an aqueous emulsion system. The degree of graft depends on the unsaturation of the rubber used as backbone. The amount of grafted EPR does not exceed 60 percent of the initial rubber; however, the amount of grafted EPDM is always higher than 60 percent of the initial rubber and increases further as the unsaturation increases. The degree of graft was found to be independent of the type of radical initiator used indicating that the abstraction of hydrogen from the rubber is carried out by the PVC radical to generate the grafting point. The graft PVC shows considerably improved processability which is equivalent to that of commercial vinyl chloride copolymers containing small amounts of propylene. It also shows dramatically improved impact strength which ranges from ten to twenty times that of PVC homopolymers.