Propylene Rubber Research Articles

Elastomer Heat-Shielding Materials Containing Aluminosilicate Microspheres

The influence of hollow aluminosilicate microspheres on the efficiency of elastomeric thermoprotective materials based on ethylene—propylene rubber is considered. The introduction of hollow aluminosilicate microspheres, even in small quantities, decreases the density and heat conductivity of such materials, with no loss of physical and mechanical properties.

Facile synthesis of ethylene–propylene fully alternating copolymer and comparison with random copolymer of similar composition

ABSTRACTA precisely sequenced ethylene–propylene (EP) fully alternating copolymer was synthesized via trans‐1,4‐polymerization of isoprene catalyzed by Ziegler–Natta catalyst followed by hydrogenation. This EP copolymer was used as model polymer for studying structure–property relationship. An ethylene–propylene random copolymer (ethylene–propylene rubber [EPR]) with similar ethylene content was also prepared for comparison, and the effect of comonomer sequence distribution on properties was investigated. The copolymer chain structures were monitored by 1H and 13C NMR and Fourier translation infrared. Differential scanning calorimetry, thermogravimetric analysis, dynamic mechanical analysis, and tensile tests were employed to determine the thermal and mechanical properties. The fully alternating copolymer EP gives a more precise glass transition comparing than EPR. Further understanding on thermal properties and aggregation behavior of ethylene–propylene copolymers is made possible by this comparative study. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45816.

Recycling polymeric waste from electronic and automotive sectors into value added products

The environmentally sustainable disposal and recycling of ever increasing volumes of electronic waste has become a global waste management issue. The addition of up to 25% polymeric waste PCBs (printed circuit boards) as fillers in polypropylene (PP) composites was partially successful: while the tensile modulus, flexural strength and flexural modulus of composites were enhanced, the tensile and impact strengths were found to decrease. As a lowering of impact strength can significantly limit the application of PP based composites, it is necessary to incorporate impact modifying polymers such as rubbery particles in the mix. We report on a novel investigation on the simultaneous utilization of electronic and automotive rubber waste as fillers in PP composites. These composites were prepared by using 25 wt.% polymeric PCB powder, up to 9% of ethylene propylene rubber (EPR), and PP: balance. The influence of EPR on the structural, thermal, mechanical and rheological properties of PP/PCB/ EPR composites was investigated. While the addition of EPR caused the nucleation of the β crystalline phase of PP, the onset temperature for thermal degradation was found to decrease by 8%. The tensile modulus and strength decreased by 16% and 19%, respectively; and the elongation at break increased by ~71%. The impact strength showed a maximum increase of ~18% at 7 wt.%–9 wt.% EPR content. Various rheological properties were found to be well within the range of processing limits. This novel eco-friendly approach could help utilize significant amounts of polymeric electronic and automotive waste for fabricating valuable polymer composites.

Influence of Impact Modifier–Coupling agent Combination on Mechanical Properties of Wood Flour–Reinforced Polypropylene Composit

The tensile properties and impact strength of wood flour-polypropylene composite with or without impact modifier and coupling agent have been investigated. The addition of maleic anhydride and dicumyl peroxide improved the tensile properties and impact strength. With increasing ethylene–propylene rubber (EPR) and maleic anhydride (MAH)–modified ethylene–propylene rubber (MEPR), impact strength were increased, whereas tensile strength and Young’s modulus were decreased. At the same EPR or MEPR content, the higher filler loadings resulted in higher Young’s modulus and lower impact strength. Tensile properties and impact strength were greatly improved by adding EPR combined with maleic anhydride–grafted polypropylene (MAPP) and dihydroquinoline.

Life assessment of marine ethylene propylene rubber power cables based on hardness retention rate

AbstractThe lifetime of ethylene propylene rubber (EPR) insulated cables will decrease because of complex aging processes. From the safety perspective, insulation condition assessment of the cable is essential to maintain an efficient and reliable operation. As a nondestructive and online evaluation method, a hardness retention rate was used to estimate the lifetime of cable. First, accelerated thermal aging tests in the laboratory were performed to measure the elongation at break retention rate (EAB%) and a hardness retention rate at different temperatures. Second, the aging values were processed by the Arrhenius equation and time temperature superposition to assess aging lifetime of insulation at different temperatures and end levels. As the insulation condition assessment of the cable by hardness retention test has no approved standard, the EAB% data were correlated with hardness retention to provide an evaluation basis. The results show that when EAB% picks out the time corresponding to a certain amount of 50% degradation, 10% of hardness retention was chosen as the termination index.

An assessment of material selection for high voltage DC extruded polymer cables

This contribution to the Electrical Insulation Special Issue provides an assessment of the present major insulation candidates, under development or ready for commercialization, for high voltage DC (HVDC) extruded polymer cables in Europe, Japan, and China. It is a contribution on behalf of the Dielectrics and Electrical Insulation Society (DEIS) Working Group on HVDC Cable Systems [1]. It is noted that interest in extruded polymer HVDC cables by IEEE Electrical Insulation Magazine dates back to the Nov/Dec 1997 issue of volume 13, when crosslinked polyethylene (XLPE) was well established and competing with ethylene propylene rubber for this technology.

Resistance to Thermal Oxidation of Ethylene Propylene Rubber and Polyhydroxybutyrate Blends

The structure, properties, and kinetics of thermal oxidation of blends based on polyhydroxybutyrate (PHB) and ethylene propylene rubber (EPR) were studied. The physicomechanical properties were studied using a ZE-40 tensile testing machine (Germany), and the crystallisation temperature Tcrand melting temperature Tmof PHB in the blends were determined on a DSM-2M differential scanning calorimeter at a scanning rate of 16°C/min. The morphology of films was determined by scanning electron microscopy on a Hitachi S-570 microscope (Japan). The kinetics of thermal oxidation of the blends was assessed according to the amount of absorbed oxygen. With increase in the PHB content in the blend there is a reduction in the elongation at break and an increase in the tensile strength and modulus. Change in the PHB content and in the oxidation time leads to negligible changes in Tcrand Tm. It was established that the greatest reactivity of blends in relation to oxygen is observed in the range of PHB concentrations of 20–40%, where the greatest phase interface area is formed. It was shown that, by changing the ratios of EPR and PHB, it is possible to control the kinetics of thermal oxidation of the blends. It was shown that, in the range of concentrations of 50–70% PHB, phase inversion occurs in the blends.

Study on grasping partial discharge development using an acoustic emission technique

To investigate the stage development of Partial Discharge (PD) for Ethylene Propylene (EP) rubber used for insulation material of joint and terminal sections of cross-linked polyethylene (XLPE) cable, we focused on the magnitude of PD and the cumulative number of PDs per unit time. It was difficult to grasp the stage development of PD by temporal variations in Acoustic Emission (AE) signal intensity and the number of counted AE signals because they contained periods during which PD activity was not high even before breakdown occurred. In contrast, the cumulative number of AE signals could clearly show a point of time when a PD might form a pit or a tree in EP.

Development and study of elastomer heat-shielding materials containing zirconium dioxide

The effect exerted by introduction of a combination of zirconium dioxide and thermally expanding graphite on the structure of the coke layer of an elastomer fireproofing and heat-shielding material based on ethylene–propylene rubber was studied. The presence of acute angles on the surface of a zirconium dioxide particle enhances its physicochemical activity in sorption (owing to excess surface energy) and promotes coking at high temperatures.

Study on the Oil Resistance, Morphological and Dynamic Mechanical Properties, Flame Retardance of Ethylene Vinyl Acetate Copolymer and Ethylene Propylene Rubber Compounds

In this experiment, blends of ethylene vinyl acetate rubber (EVM) with a vinyl acetate (VA) content greater than 40 wt% and ethylene propylene rubber (EPM) were prepared by mechanical mixing; a number of parameters of the blends, including oil resistance, morphological and dynamic mechanical properties and flame retardancy, were subsequently measured. In the 100℃ oil resistance test, both the ammonium polyphosphate/dipentaerythritol/expandable graphite (APP/DPER/EG) and aluminum hydroxide (ATH) flame retardant systems showed an increase in volume change with increasing EPM content. For the ATH system, the dispersion shape was coarse and aggregation was observed. The results of a dynamic mechanical test showed slightly higher E` and E`` for the APP/DPER/EG flame retardant system when compared to the single ATH system. For both the APP/DPER/EG and ATH systems, the limited oxygen index (LOI) tests performed at increasing content of EPM showed a LOI value higher than 30, indicating excellent flame resistance.

Morphology, crystalline features, and tensile properties of syndiotactic polypropylene blends

ABSTRACTSyndiotactic polypropylene (sPP) was modified with ethylene–octene copolymer (EOC) and ethylene–propylene rubber (EPR), with test samples prepared in a twin‐screw extruder and then injection‐molded. The phase morphology, rheology, and thermal and tensile properties of the modified sPP were investigated. Atomic force microscopy studies showed how the phase morphology of the sPP blends with elastomers depended on the blend compositions, and the results compared with the storage modulus at low frequency. EOC and EPR were dispersed phase in an sPP matrix with spherical shapes when the dispersed content was 20 wt % or lower. The phase cocontinuity started around 40 wt % EOC for the sPP–EOC blends and around 60 wt % EPR for the sPP–EPR. The dispersed phase then formed more complex elongated shapes. The rheological and thermal properties were affected by the sPP–elastomer interphase. EOC promoted the crystallization of sPP; this increased the crystallization temperature and rate. In contrast, EPR had the opposite effect on the crystallization behavior, and the results indicate that sPP and EPR were not completely separated. The tensile properties were studied from −20 to 100 °C. We found that the tensile properties at low temperature could be improved without a loss in high‐temperature properties. In the particular case of 20 wt % EOC, both the strain at yield and strain at break of the sPP–EOC blend were improved at both −20 and 100 °C. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44611.

Influence of the rubber content and particle morphology on the mechanical properties of the (hiPP)

ABSTRACTThe effect of the final morphology and the role of ethylene propylene rubber (EPR) content and (iPP) particle size on the mechanical properties of (iPP/EPR) in situ blends are investigated. The addition of EPR causes a significant improvement in the impact strength of the composites, from 20 kJ/m2 in unthoughned composite iPP to 100 kJ/m2 in iPP/EPR composites containing 50% EPR. Conversely, the tensile strength and the Young's modulus of the blends decrease as the EPR amount increases. The mechanical tensile strength is similar for the composite which have a time of homopolymerization less or equal to 60 min, and a higher value is observed in the case of 100 min. The scanning electron microscopy characterization shows that the larger the iPP particle is, the less the rubber settles on the surface of the high impact polypropylene and the less the final material is resistant to shocks. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44197.

Controlling dielectric permittivity and dielectric loss by starch‐coated silver nanoparticles in ethylene–propylene rubber

In this study, the effects of silver nanoparticles (AgNP) and starch‐coated ones (AgNP/starch) on dielectric properties of ethylene–propylene rubber (EPR) composites were compared. The dielectric permittivity of AgNP/EPR with 8 vol% of AgNP achieved 336 at 1 kHz which specifies the percolation threshold. AgNP/EPR composite with 6 vol% of filler as a near‐percolation sample was chosen to study the contribution of starch on dielectric properties. The AgNP/EPR composite showed relatively high dielectric permittivity and loss tangent ( , at 1 kHz), whereas AgNP/starch/EPR composite showed lower permittivity and loss ( , at 1 kHz), but with the advantage of more reduction in dielectric loss than dielectric permittivity. Moreover, better compatibility was observed between EPR and AgNP/starch particles, resulting in better dispersion of this coated filler, compared to AgNP. POLYM. COMPOS., 39:1303–1310, 2018. © 2016 Society of Plastics Engineers

The properties of ethylene–propylene elastomers obtained with the use of a new cross-linking substance

In this work, the effect of a new filler on cross-linking of ethylene–propylene rubber (EPM) was investigated. A filler with a core–shell structure ZnO/SiO2 (precipitated silica modified with zinc oxide) was introduced into rubber compounds. It was proved using of those substance to cross-link EPM caused the formation of labile ionic clusters in elastomer network. These non-covalent cross-links were generated due to interactions occurring between metal ions and functional groups of rubber (namely carboxyl groups) introduced via rubber functionalization with maleic and itaconic acids derivatives. The optimal curing time of rubber compounds was investigated. The cross-link density of the vulcanizates obtained was studied by equilibrium swelling in solvents (e.g., toluene). Additionally, the results confirmed that vulcanizates received using modified silica contained specific cross-links disintegrating under ammonia vapors. Physical relaxation at ambient temperature confirmed the influence of non-covalent cross-links on stress dissipation in the vulcanizate. The static and dynamic mechanical properties of vulcanizates obtained were also determined.

Mechanism elucidation of degradation dynamics of ethylene propylene rubber cable insulations sampled from nuclear power containment using additional aging

Ethylene propylene rubber insulation under operation for 16 years in boiling water reactor containments was subjected to additional thermal aging at 110°C. After 70 days of aging, the mechanical property of the insulation was decreased such that the limit guaranteeing durability against design-basis events was breached. This degradation rate is three times slower than that predicted on the basis of an accelerated aging test with control samples. Infrared spectroscopic analysis revealed suppression in the formation of carbonyl products in the service-used cables. According to the gel fraction measurement, cross-linking is the dominant reaction in such service cables. The unique slow degradation dynamics observed in service cables could be attributed to such oxidation control and the cross-linking reaction. The present study also conducts nuclear magnetic resonance analysis to elucidate the cross-linking point in the main chain.

In search of extendable conditions for cable environmental qualification in nuclear power plants

ABSTRACTThe environmental qualification (EQ) for cable insulators in nuclear power plants (NPPs) has been developed on the basis of the design basis accident (DBA) to prevent reactor core damage. However, the latest safety principles require extending the design concept to prepare the utilized equipment for scenarios after core damage. Thus, we propose a modification to the EQ for cables connecting utilized equipment at design extension conditions. This paper surveys all electrical components for accident management in boiling water reactor-4 (BWR-4), and identifies their connecting cables’ functional category as low-voltage power, instrumentation, and control cables. The EQ temperature profile of these cables during the incident phase was addressed for extension. This required postulating maximum temperature environments according to accident scenarios, knowledge of cable integrity degradation, and their current evaluation by the EQ. To evaluate whether these environments are suitable stressors, heat testing was conducted on flame-retardant ethylene propylene rubber (FR-EPR)-insulated cables. On the basis of those results, we suggest a maximum primary peak temperature of the EQ temperature profile of 250 °C. We also suggest increasing the primary peak period of the EQ temperature profile to 48 h without experiment, on the basis of inherent excessive margin for mechanical integrity during the ageing phase.

Rheology of polypropylene/poly(ethylene-co-propylene) in-reactor alloy

The interfacial adhesion and molecular structure of an in-reactor polypropylene/ethylene propylene rubber alloy were studied with respect to the rheological behavior and final properties of the alloy. The polymer alloys have similar structural parameters but different impact properties. The samples were characterized by gel permeation chromatography, thermal analysis, rheological analysis and mechanical testing. Fractionation of samples showed that the quantities of components are the same. Gel permeation chromatography results showed that molecular weight distribution of all components were similar. Thermal analysis results showed that the crystal size of two samples was the same but the crystal contents were different. In studying the impact strength, it was revealed that a large difference exists between the two samples. The small amplitude oscillation rheometry indicates that the rheological parameters have a glaring difference in both samples that can be an evidence of interfacial adhesion in the in-reactor alloys having so many similar structural parameters.

Specimen Geometry Effect on the Deformation Mechanisms of Polypropylene-Based Composites Under Impact Loading at Different Temperatures

Dynamic behaviors of polypropylene (PP), PP–ethylene propylene rubber (PP–EPR) and PP–nanoclay (PP–Nanocor) composites were studied by using split Hopkinson pressure bar at different temperatures and under different strain rates. Samples with two different geometries and with or without petroleum jelly lubricant were tested under identical testing conditions to compare the dynamic responses with underlying deformation mechanisms. For all the test temperatures and strain rates, the dynamic responses of neat PP and PP–Nanocor showed post-yield strain-softening, whereas those of PP–EPR showed strain-hardening after the yield point. PP–Nanocor showed more strain-softening compared with neat PP at room temperature due to the more important localized shearing deformation at the nanofiller/matrix interfaces. Friction between the sample and the bars affected the dynamic response of the materials at room temperature as well as high temperatures seen as differences in behavior between the dynamic behaviors of the non-lubricated thin samples and the non-lubricated thick samples under the same testing conditions. At room temperature and without lubrication, the thicker specimens of neat PP and PP–Nanocor failed during dynamic testing due to the barreling-induced crack that propagated in the specimen and led to the formation of a peripheral fragment. Although petroleum jelly provided a satisfactory lubrication condition for both neat PP and PP-based composites at room temperature and at high temperatures, by reducing the friction effect on the yield behavior, the lubrication did not have a significant effect on the post-yield behavior of neat PP and PP–Nanocor, particularly for the room temperature testing and with the thick specimens.

Effect of insulator environment on thermal ageing estimations for ethylene propylene rubber insulated nuclear power plant cables

ABSTRACTThermal ageing estimations merely focus on the degradation of cable insulator materials without considering their arrangement within the cable structure, by surrounding jacket or colorant pigments. This study reconsidered thermal ageing estimations based on the insulator elongation at break (EAB) degradation progress for flame retardant ethylene propylene rubber (FR-EPR) insulators within the whole cable structure. FR-EPR insulators were aged using two methods. In the first method, the insulators were heated, including jacket material at 125 °C, 150 °C, and 160 °C for 2208, 336, and 264 h, respectively. In the second method, the insulators were heated without jacket at 125 °C for 3480 h, and at 160 °C for 264 h. It was expected that the EAB degradation progress would be more severe when the FR-EPR insulators were aged without jacket. However, the results contradicted previous expectations, and the special heat-resistant polyvinyl chloride jacket accelerated the EAB degradation. In addition, the black FR-EPR insulators showed values that deviated from the predictions for the activation energy (Ea) and equivalent times compared to the white and red insulators due to the use of carbon black as a pigment. The reduced equivalent times for thermally aged FR-EPR insulators with jacket in this study were evident compared with the current degradation database for FR-EPR insulators degraded without jacket.

Study of Thermal Properties of Mixed (PP/EPR)/ABS with Five Model Compatibilizers

The influences of incorporating compatibilizers E-EA-MAH, E-MA-GMA, E-AM, SEBS KRATON G, or PP-g-MAH on the thermal properties of mixed (polypropylene/ethylene propylene rubber)/acrylonitrile butadiene styrene (PP/EPR)/ABS have been investigated. DSC investigations have revealed that the incorporation of 5% of ABS in the copolymer (PP/EPR) does not fundamentally affect the thermal properties of the basic copolymer; additionally, the addition of 1.5% of each of the compatibilizers in the basic mixture does not significantly alter the crystallization temperature values and the melting of the -P- sequences. There is a variation of melting enthalpy values of the -P- sequences of 18.23% using SEBS KRATON G and of 10.38% using E-AM-GMA. When the rate of each of the compatibilizers increases to 5%, overall crystallization enthalpies of -P- sequences are almost kept unchanged, except for the case of using the compatibilizer E-AM-GMA with a variation of 8.42%. There is a minor variation of the melting enthalpy of -P- sequences with higher levels of compatibilizer. The incorporation of 5% ABS copolymer in the PP/EPR does not significantly alter the thermal properties of the basic structure of (PP/EPR)/ABS.