Mechanical property and morphology comparison between the two blends poly(propylene)/ethylene‐propylene‐diene monomer elastomer and poly(propylene)/maleic anhydride‐g‐ethylene‐propylene‐diene monomer

The comparison of the mechanical properties between poly(propylene)/ethylene‐propylene‐diene monomer elastomer (PP/EPDM) and poly(propylene)/maleic anhydride‐g‐ethylene‐propylene‐diene monomer [PP/MEPDM (MAH‐g‐EPDM)] showed that the latter blend has noticeably higher Izod impact strength but lower Young's modulus than the former one. Phase morphology of the two blends was examined by dynamic mechanical thermal analysis, indicating that the miscibility of PP/MEPDM was inferior to PP/EPDM. The poor miscibility of PP/MEPDM degrades the nucleation effectiveness of the elastomer on PP. The observations of the impact fracture mode of the two blends and the dispersion state of the elastomers, determined by scanning electron microscopy, showed that PP/EPDM fractured in a brittle mode, whereas PP/MEPDM in a ductile one, and that a finer dispersion of MEPDM was found in the blend PP/MEPDM. These observations indicate that the difference in the dispersion state of elastomer between PP/EPDM and PP/MEPDM results in different fracture modes, and thereby affects the toughness of the two blends. The finer dispersion of MEPDM in the blend of PP/MEPDM was attributed to the part cross‐linking of MEPDM resulting from the grafting reaction of EPDM with maleic anhydride (MAH) in the presence of dicumyl peroxide (DCP). © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2486–2491, 2002     

Effect of ultrasound on extrusion of PP/EPDM blends: Structure and mechanical properties

The effects of ultrasonic irradiation on the mechanical properties, morphology, and crystal structure of polypropylene (PP)/ethylene‐propylene‐diene terpolymer (EPDM) blends were examined. Results show that appropriate irradiation intensity can noticeably increase the toughness of the PP/EPDM blends without reducing rigidity. Scanning electron microscopic (SEM) observation shows that with ultrasonic irradiation, the morphology of a well‐dispersed EPDM phase is formed in the PP/EPDM blend. The glass transition temperatures of PP and EPDM phase approach each other as a result of ultrasonic irradiation. Differential Scanning Calorimetric (DSC) analysis indicates that the crystallinities of the PP and EPDM phases increase with ultrasonic irradiation, and β crystals of PP form in the PP/EPDM blend with ultrasonic irradiation, which is proven by wide angle X‐ray diffraction (WAXD) analysis. Polym. Eng. Sci. 44:1509–1513, 2004. © 2004 Society of Plastics Engineers.     

Rheological and thermal properties of binary blends of polypropylene and poly(ethylene‐CO‐1‐octene)

Dynamic viscoelastic properties of binary blends consisting of an isotactic polypropylene (i‐PP) and ethylene‐1‐octene copolymer (PEE) were investigated to reveal the relation between miscibility in the molten state and the morphology in the solid state. In this study, PEE with 24 wt % of 1‐octene was employed. The PEE/PP blend with high PEE contents showed two separate glass‐relaxation processes associated with those of the pure components. These findings indicate that the blend presents a two‐phase morphology in the solid state as well as in the molten state. The PEE/PP blend with low PEE content showed a single glass‐relaxation process, indicating that PEE molecules were probably incorporated in the amorphous region of i‐PP in the solid state. The DMTA analysis showed that the blends with low PEE contents presented only one dispersion peak, indicating a certain degree of miscibility between the components of these blends. These results are in accordance with the results of the rheological analysis. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1634–1639, 2001     

Radiation‐processed polychloroprene‐co‐ethylene–propene diene terpolymer blends: Evaluation of blend morphology,miscibility, and physical properties

The miscibility of polychloroprene rubber (CR) and ethylene–propylene–diene terpolymer rubber (EPDM) was studied over the entire composition range. Different blend compositions of CR and EPDM were prepared by initially mixing on a two‐roll mill and subsequently irradiating to different gamma radiation doses. The blends were characterized by differential scanning calorimetry, Fourier transform infrared spectroscopy, density measurement, hardness measurement, and solvent permeability analysis. The compatibility of the blends was studied by measuring the glass transition temperature and heat capacity change of the blends. The immiscibility of blends was reflected by the presence of two glass transition temperatures; however, partial miscible domains were observed due to inter diffusion of phases. Permeation data fitted best with the Maxwell's model and indicated that in CR‐EPDM blends, EPDM exists as continuous phase with CR as dispersed phase for lower CR weight fractions and phase inversion occurred in 40–60% CR region. It was observed that CR improved oil resistance of EPDM; however, the effect was prominent for blends of >20% CR content. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Experimental investigation of the morphology development and mechanical properties of waste ethylene propylene diene monomer/polypropylene blend in modular intermeshing corotating twin‐screw extruder

Nowadays, with the increase in the number of automobiles, waste EPDM (ethylene propylene diene monomer) is causing a significant environmental problem. From environmental and economical perspectives, recycling is one of the popular methods to solve environmental problems. This study, which involved waste EPDM/PP (polypropylene) blends with the ratio range of 70/30 and 75/25, set out to ascertain the relevance of the mass percentage of the dispersed phase, the influence of the screw geometry, the screw rpm, and the melting temperature of PP materials on the morphology and mechanical properties of the waste rubber blend. The purpose of this study is to develop a high‐value thermoplastic elastomer from waste EPDM. This investigation concentrated on determining the optimum conditions for producing a blend by extrusion, relative to screw geometry, screw rational speed, and operating temperature. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2276–2282, 2002     

Dynamic mechanical properties and morphological structure of PS/EPDM blends prepared by in situ‐polymerization of styrene

PS/EPDM blends prepared by in situ‐polymerization of styrene in the presence of EPDM are immiscible and show two phases. Furthermore, the dynamic mechanical behavior of injected specimens is quite different from that of noninjected blends. This is attributed to the differences in morphology before and after injection molding. The morphology of the noninjected blends consists of PS spherical domains covered by a thin layer of EPDM, whereas the injected blends show elastomeric dispersed phase morphology in a rigid matrix. SEM analysis was important to elucidate the changes in the dynamic mechanical behavior of PS/EPDM blends, but TEM analysis is more precise for morphological characterization and yielded the real average diameter of EPDM particles. Comparing the average diameters for the PS/EPDM blends obtained from SEM and TEM analyses, the diameters obtained from the SEM analysis are wider than those of TEM which is due to the solvent extraction effect on the blend morphology. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

The control of miscibility of PP/EPDM blends by adding lonomers and applying dynamic vulcanization

The control of miscibility for isotactic polypropylene (PP) and ethylene-propylene-diene terpolymer (EPDM) has been attempted by adding poly(ethylene-comethacrylic acid) (EMA) ionomers and by applying dynamic vulcanization. The rheological properties, crystallization behavior, and morphology of the dynamically vulcanized EPDM/PP/ionomer ternary blends were investigated with a Rheometrics dynamic spectrometer (RDS), a differential scanning calorimeter (DSC), and a scanning electron microscope (SEM). Two kinds of EMA ionomers neutralized with different metal ions (Na⁺ and ZN⁺⁺) were investigated. Blends were prepared on a laboratory internal mixer at 190°C. Blending and curing were performed simultaneously, i.e., EPDM was vulcanized with dicumyl peroxide (DCP) in the presence of PP/ionomer. The composition of PP and EPDM was fixed at 50/50 by wt% and the contents of EMA ionomer were vaired from 5 to 20 parts based on the total amount of PP and EPDM. It was found that the addition of ionomers and the application of the dynamic vulcanization were effective in enhancing the miscibility of PP and EPDM. The structure of the blends was controlled by the following three component phases, i.e., the phase of the dynamially valcanized EPDM, PP, and Zn-neutralized ionomer. The ternary blends showed more miscibility than the PP/EPDM binary blend. This is due to the thermoplastic interpenetrating polymer network (IPN) of the ternary blends. The structure and properties of the ternary blends differed, depending on the types and contents of ionomer, i.e., the ternary blend containing Na-neutralized ionomer did not show a thermoplastic IPN structure clearly, even though the blend was prepared by dynamic vulcanization. The ternary blend containing Zn-neutralized ionomer clearly showed the behavior of a thermoplastic IPN when the contents of ionomer and DCP were 15 parts and 1.0 part, respectively.     

Properties and morphologies of elastomer blends modified with EPDM‐g‐poly[2‐dimethylamino ethylmethacrylate]

The graft copolymerization of 2‐dimethylamino ethylmethacrylate (DMAEMA) onto ethylene propylene diene mononer rubber (EPDM) was carried out in toluene via solution polymerization technique at 70°C, using dibenzoyl peroxide as initiator. The synthesized EPDM rubber grafted with poly[DMAEMA] (EPDM‐g‐PDMAEMA) was characterized with ¹H‐NMR spectroscopy, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA). The EPDM‐g‐PDMAEMA was incorporated into EPDM/butadiene acrylonitrile rubber (EPDM/NBR) blend with different blend ratios, where the homogeneity of such blends was examined with scanning electron microscopy and DSC. The scanning electron micrographs illustrate improvement of the morphology of EPDM/NBR rubber blends as a result of incorporation of EPDM‐g‐PDMAEMA onto that blend. The DSC trace exhibits one glass transition temperature (T_g) for EPDM/NBR blend containing EPDM‐g‐PDMAEMA, indicating improvement of homogeneity. The physico‐mechanical properties after and before accelerated thermal aging of the homogeneous, and inhomogeneous EPDM/NBR vulcanizates with different blend ratios were investigated. The physico‐mechanical properties of all blend vulcanizates were improved after and before accelerated thermal aging, in presence of EPDM‐g‐PDMAEMA. Of all blend ratios under investigation EPDM/NBR (75/25) blend possesses the best physico‐mechanical properties together with the best (least) swelling (%) in brake fluid. Swelling behavior of the rubber blend vulcanizates in motor oil and toluene was also investigated. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Silica‐reinforced dynamically vulcanized ethylene–propylene–diene monomer/polypropylene thermoplastic elastomers: Morphology,rheology, and dynamic mechanical properties

Attempts were made to prepare dynamically crosslinked ethylene–propylene–diene monomer/polypropylene (EPDM/PP, 60/40 w/w) blends loaded with various amounts of silica as a particulate reinforcing agent. The dispersion of silica between the two phases under mixing conditions, and also extent of interaction, as the two main factors that influence the blend morphology were studied by scanning electron microscopy. Increasing the silica concentration led to the formation of large‐size EPDM aggregates shelled by a layer of PP. Dynamic mechanical thermal analysis performed on the dynamically cured silica‐loaded blend samples showed reduction in damping behavior with increasing silica content. Higher rubbery‐like characteristics under tensile load were exhibited by the silica‐filled EPDM/PP‐cured blends. However, increasing the silica level to 50 phr led to the enhancement of interface, evidenced by increases in the tensile modulus and extensibility of the blend compared with those of the unloaded sample. Addition of a silane coupling agent (Si69) into the mix improved the mechanical properties of the blend, attributed to the strengthening of interfacial adhesion between the PP matrix and silica‐filled EPDM phase. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2000–2007, 2004     

The morphology and property of ultra‐fine full‐vulcanized acrylonitrile butadiene rubber particles/EPDM blends

A novel UFNBRP/EPDM blend was prepared by compounding ultra‐fine full‐vulcanized acrylonitrile butadiene rubber particles (UFNBRP) with ethylene–propylene–diene monomer (EPDM) matrix. The morphology, dynamic property, and curing property of the blend were discussed in detail. TEM and SEM observations showed that, no matter how high the blend ratio of UFNBRP to EPDM matrix was, UFNBRP particles always kept being in the dispersion phase because of its extremely high viscosity resulting from self‐crosslinking, but were not dispersed as nanosize units, as expected. Dynamic properties, illustrated by DMTA, further demonstrated that two phases exhibited two separate glass transition temperatures, indicating distinct phase separation and weak phase interaction. Rubber processing analyzer results showed that inorganic filler as well as UFNBRP particles in EPDM matrix formed a network and blocked the flow properties of the compound. At the same time, the introduction of UFNBRP particles evidently affected the vulcanization of EPDM, when sulfur was used as a vulcanizing agent, and improved the mechanical properties of EPDM. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3673–3679, 2006     

Dynamic mechanical analysis of ethylene–propylene–diene monomer rubber and styrene–butadiene rubber blends

The effects of blend ratio, crosslinking systems, and fillers on the viscoelastic response of ethylene–propylene–diene monomer (EPDM)/styrene–butadiene rubber (SBR) blends were studied as functions of frequency, temperature, and cure systems. The storage modulus decreased with increasing SBR content. The loss modulus and loss tangent results showed that the EPDM/SBR blend vulcanizate containing 80 wt % EPDM had the highest compatibility. Among the different cure systems studied, the dicumyl peroxide cured blends exhibited the highest storage modulus. The reinforcing fillers were found to reduce the loss tangent peak height. The blend containing 40 wt % EPDM showed partial miscibility. The dispersed EPDM phase suppressed the glass‐transition temperature of the matrix phase. The dynamic mechanical response of rubbery region was dominated by SBR in the EPDM–SBR blend. The morphology of the blend was studied by means of scanning electron microscopy. The blend containing 80 wt % EPDM had small domains of SBR particles dispersed uniformly throughout the EPDM matrix, which helped to toughen the matrix and prevent crack propagation; this led to enhanced blend compatibility. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Influence of phase modifiers on morphology and properties of thermoplastic elastomers prepared from ethylene propylene diene rubber and isotactic polypropylene

A series of thermoplastic elastomers (TPEs) were prepared from a binary blend of ethylene propylene diene rubber (EPDM) and isotactic polypropylene (iPP) using different types of phase modifiers. The influence of sulphonated EPDM, maleated EPDM, styrene‐ethylene‐co‐butylene‐styrene block copolymer, maleated PP, and acrylated PP as phase modifiers showed improved physico‐mechanical properties (like maximum stress, elongation at break, moduli, and tension set). Scanning electron and atomic force microscopy studies revealed better morphologies obtained with these phase modified EPDM‐iPP blends. The dependence of the phase modifier type and concentration was optimized with respect to the improvement in physical properties and morphology of the blends. Physical properties, dynamic mechanical properties, and morphology of these blends were explained with the help of interaction parameter, melt viscosity, and crystallinity of the blends. Theoretical modeling showed that Kerner, Ishai‐Cohen, and Paul models predicted the right morphology–property correlation for the prepared TPEs. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers.     

Time‐resolved light scattering and FTIR spectroscopic studies on blends of polypropylene grafted with maleic anhydride and zinc salt of sulfonated EPDM lonomer

Time‐resolved light scattering and Fourier‐transform infrared (FTIR) spectroscopic studies were performed on blends of polypropylene‐g‐maleic anhydride (PPg‐MAH) and sulfonated EPDM ionomer neutralized with zinc cation (ZnSEPDM). The temperature exhibiting maximum crystalline growth rate (T_G,max) decreased as ZnSEPDM contents were increased. The results of wide‐angle X‐ray diffraction also confirmed that the degree of crystallinity of PP‐g‐MAH decreased when the content of the ionomer was increased. A shift in the glass transition temperatures of both EPDM and PP phases in the blends was observed, confirming the enhanced miscibility between PP and EPDM. It was concluded from the FTIR spectroscopic studies that the enhanced miscibility is caused by a specific interaction between PP‐g‐MAH and ZnSEPDM.     

Morphology prediction and the effect of core‐shell structure on the rheological behavior of PP/EPDM/HDPE ternary blends

In this work, the morphologies of polypropylene (PP)/ethylene‐propylene‐diene (EPDM) rubber/high density polyethylene (HDPE) 70/20/10 blends were studied and compared with the predictions of the spreading coefficient and minimum free energy models. The interfacial tension of PP/HDPE, PP/EPDM, and HDPE/EPDM blends were obtained by fitting the experimental dynamic storage modulus data to Palierne's theory. The prediction results showed core‐shell morphology (core of HDPE and shell of EPDM) in PP matrix. The PP/EPDM/HDPE blends were respectively prepared by direct extrusion and lateral injection method. Core‐shell morphology (core of HDPE and shell of EPDM) could be obtained with direct extrusion corresponding to the predicted morphology. The morphology of PP/EPDM/HDPE blends could be effectively controlled by lateral injection method. For PP/EPDM/HDPE blend prepared by lateral injection method, HDPE and EPDM phase were dispersed independently in PP matrix. It was found that the different morphology of PP/EPDM/HDPE blends prepared by two methods showed different rheological behavior. When the core‐shell morphology (core of HDPE and shell of EPDM) appeared, the EPDM shell could confine the deformation of HDPE core significantly, so the interfacial energy contribution of dispersed phase on the storage modulus of blends would be weaken in the low frequency region. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Synergetic toughness and morphology of poly(propylene)/nylon 11/maleated ethylene‐propylene diene copolymer blends

Polypropylene (PP)/nylon 11/maleated ethylene‐propylene‐diene rubber (EPDM‐g‐MAH) ternary polymer blends were prepared via melt blending in a corotating twin‐screw extruder. The effect of nylon 11 and EPDM‐g‐MAH on the phase morphology and mechanical properties was investigated. Scanning electron microscopy observation revealed that there was apparent phase separation for PP/EPDM‐g‐MAH binary blends at the level of 10 wt % maleated elastomer. For the PP/nylon 11/EPDM‐g‐MAH ternary blends, the dispersed phase morphology of the maleated elastomer was hardly affected by the addition of nylon 11, whereas the reduced dispersed phase domains of nylon 11 were observed with the increasing maleated elastomer loading. Furthermore, a core‐shell structure, in which nylon 11 as a rigid core was surrounded by a soft EPDM‐g‐MAH shell, was formed in the case of 10 wt % nylon 11 and higher EPDM‐g‐MAH concentration. In general, the results of mechanical property measurement showed that the ternary blends exhibited inferior tensile strength in comparison with the PP matrix, but superior toughness. Especially low‐temperature impact strength was obtained. The toughening mechanism was discussed with reference to the phase morphology. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Influence of Copolymer Composition and Curing on Toughness of Isotactic Polypropene Blended Together with Metallocene‐EPDM and Ethene/Propene/Vinylcyclohexane Terpolymers

Ethene/propene terpolymers containing either 1‐vinylcylohexene‐4 (VCHen) or vinylcyclohexane (VCHan) as termonomer component were prepared using MAO‐activated rac‐Me₂Si(2‐MeBenz[e]Ind)₂ZrCl₂ (MBI). Propene content was varied between 26 and 72 wt.‐% with less than 1 mol‐% termonomer incorporation. Blends containing 85 vol.‐% isotactic polypropene (i‐PP) and 15 vol.‐% of the two EP terpolymer families were prepared by melt‐compounding in a twin‐screw kneader at 200°C to examine the role of sulfur‐mediated crosslinking of the unsaturated EPDM terpolymer phase in comparison to the corresponding blends containing non‐crosslinked saturated EP/VCHan terpolymers. The observed glass temperature (T_g) depression of the T_g of EP(D)M phases with respect to the T_g of the corresponding bulk EP(D)M was attributed to the presence of thermally induced stresses in both blend systems. Blends of i‐PP with crosslinked EPDM showed smaller T_g depression with respect to those of iPP/EPM blends containing non‐crosslinked EP and EPM dispersed phases. Morphology differences were detected for i‐PP/EPM and dynamically vulcanized i‐PP/EPDM blends by means of atomic force microscopy (AFM). The crosslinked i‐PP/EPDM blends exhibited significantly improved low temperature toughness as compared to the corresponding non‐crosslinked i‐PP/EPM blends. Curing of the EPDM elastomer phase in i‐PP/EPDM (85 vol.‐%/15 vol.‐%) blends afforded significantly improved toughness/stiffness balance and a wider toughness window with respect to the corresponding i‐PP/EPM and i‐PP/EP blends without sulfur‐cured rubber phases.     

Influence of processing conditions on dual‐phase continuous blend system of thermoplastic polyurethane with ethylene‐propylene‐diene monomer elastomer

In the present work, we extend the investigation on the influence of processing conditions on the morphology, the mechanical properties, and the rheology of the blends of thermoplastic polyurethane (TPU) and ethylene–propylene–diene monomer elastomer (EPDM). Scanning and transmission electron microscopies show that the dual‐phase continuous morphology of the blends was strongly dependant on the EPDM composition, processing temperature, and the shear rates. The network structure of the EPDM domain in TPU matrix became finest and most regular for the blends containing 7 wt % EPDM. It was also found that high shear rate favored the formation of the perfect network structure. Furthermore, the blends prepared at 180°C present finer and more perfect network structure than those at the other processing temperatures. The competition of compatible and incompatible segments of TPU with EPDM during melt blending plays an important role in development of the dual‐phase continuous morphology. This was reflected through the influence of processing conditions on the rheological properties, and was also verified by the Davies equation's prediction. The tensile properties present a significant improvement with addition of EPDM, and obtained the optimum value for the blends containing 7 wt % EPDM. The influence of different processing parameters on the mechanical properties is associated with their influence on the morphology, and better tensile properties are obtained in the processing conditions, in which, the finer and more perfect network structure of EPDM domain is presented. These facts confirm that the dual‐phase continuous morphology is the main advantage for higher tensile strength, elongation at break, and Young's modulus can be well controlled by different processing conditions for the improvement of mechanical properties. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5472–5482, 2006     

Effect of dynamic crosslinking on tensile yield behavior of polypropylene/ethylene‐propylene‐diene rubber blends

Tensile yield behavior of the blends of polypropylene (PP) with ethylene‐propylene‐diene rubber (EPDM) is studied in blend composition range 0–40 wt % EPDM rubber. These blends were prepared in a laboratory internal mixer by simultaneous blending and dynamic vulcanization. Vulcanization was performed with dimethylol phenolic resin. For comparison, unvulcanized PP/EPDM blends were also prepared. In comparison to the unvulcanized blends, dynamically vulcanized blends showed higher yield stress and modulus. The increase of interfacial adhesion caused by production of three‐dimensional network is considered to be the most important factor in the improvement. It permits the interaction of the stress concentrate zone developed at the rubber particles and causes shear yielding of the PP matrix. Systematic changes with varying blend composition were found in stress‐strain behavior in the yield region, viz., in yield stress, yield strain, width of yield peak, and work of yield. Analysis of yield stress data on the basis of the various expressions of first power and two‐thirds power laws of blend compositions dependence and the porosity model led to consistent results from all expression about the variation of stress concentration effect in both unvulcanized and vulcanized blend systems. Shapes and sizes of dispersed rubber phase (EPDM) domains at various blend compositions were studied by scanning electron microscopy. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 2104–2121, 2000     

Influence of the rubbery phase on the crystallinity and thermomechanical properties of poly(3‐hydroxybutyrate)/elastomer blends

Poly(3‐hydroxybutyrate) (PHB) is a very promising biopolymer. In order to improve its processability and decrease its brittleness, PHB/elastomer blends can be prepared. In the work reported, the effect of the addition of a rubbery phase, i.e. ethylene–propylene–diene terpolymer (EPDM) or poly(vinyl butyral) (PVB), on the properties of PHB was studied. The effects of rubber type and of changing the PHB/elastomer blend processing method on the crystallinity and physical properties of the blends were also investigated. For blends based on PHB, the main role of EPDM is its nucleating effect evidenced by a decrease of crystallization temperature and an increase of crystallinity with increasing EPDM content regardless of the processing route. While EPDM has a weak effect on PHB glass transition temperature, PVB induces a marked decrease of this temperature thank to its plasticizer that swells the PHB amorphous phase. A promising solution to improve the mechanical properties of PHB seems to be the melt‐processing of PHB with both plasticizer and EPDM. In fact, the plasticizer is more efficient than the elastomer in decreasing the PHB glass transition temperature and, because of the nucleating effect of EPDM, the decrease of the PHB modulus due to the plasticizer can be counterbalanced. Copyright © 2010 Society of Chemical Industry     

Influences of trans‐polyoctylene rubber on the physical properties and phase morphology of natural rubber/acrylonitrile–butadiene rubber blends

The influence of trans‐polyoctylene rubber (TOR) on the mechanical properties, glass‐transition behavior, and phase morphology of natural rubber (NR)/acrylonitrile–butadiene rubber (NBR) blends was investigated. With an increased TOR level, hardness, tensile modulus, and resilience increased, whereas tensile strength and elongation at break tremendously decreased. According to differential scanning calorimetry and dynamic mechanical analysis, there were two distinct glass‐transition temperatures for a 50/50 NR/NBR blend, indicating the strongly incompatible nature of the blend. When the TOR level was increased, the glass transition of NBR was strongly suppressed. NBR droplets of a few micrometers were uniformly dispersed in the continuous NR phases in the NR/NBR blends. When TOR was added to a 50/50 NR/NBR blend, TOR tended to be located in the NR phase and in some cases was positioned at the interfaces between the NBR and NR phases. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 125–134, 2002