Effects of the compatibilizer structural parameters on microstructural formation in ethylene–propylene–diene monomer rubber/ethylene–propylene–diene monomer rubber‐g‐maleic anhydride/organoclay nanocomposites

Nanocomposite vulcanizates based on ethylene–propylene–diene monomer rubber (EPDM) and organically modified montmorillonite with improved mechanical and barrier properties were prepared via a melt‐mixing process in the presence of maleic anhydride grafted ethylene–propylene–diene monomer rubber (EPDM‐g‐MAH) as an interfacial compatibilizer. The effects of the EPDM Mooney viscosity as the matrix and also the compatibilizer molecular weight and its maleation degree on the developed microstructure were also studied. The annealing of the vulcanized nanocomposites based on a low‐Mooney‐viscosity EPDM matrix and low‐Mooney‐viscosity EPDM‐g‐MAH enhanced the flocculation of the dispersed clay platelets; this implied that the flocculated structure for the clay nanolayers was more thermodynamically preferred in these nanocomposites. This was verified by the decrease in the oxygen permeability of the nanocomposite vulcanizates with increasing annealing time. The tendency of the clay nanosilicate layers to flocculate within the matrix of EPDM was found to be influenced by the clay volume fraction, the maleation degree, and also, the Mooney viscosity of the compatibilizer. Interfacially compatibilized nanocomposites based on high‐molecular‐weight EPDM exhibited a more disordered dispersion of the clay nanolayers, with a broadened relaxation time spectra; this was attributed to the higher shearing subjected to the mix during the melt‐blending process. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

NR/SBR/organoclay nanocomposites: Effects of molecular interactions upon the clay microstructure and mechano‐dynamic properties

Nanocomposites based on (70/30) blends of natural rubber (NR), styrene‐butadiene rubber (SBR), and organoclay (OC) have been prepared successfully via melt‐mixing process. Effects of the extent of polymers/clay interactions upon the developed microstructure, fatigue life, and dynamic energy loss by the nanocomposites have been investigated. Maleated EPDM (EPDM‐g‐MAH) and epoxidized NR (ENR50) were employed as compatibilizer. Nanocomposites were characterized by means of X‐ray diffractometer (XRD), transmission electron microscope (TEM), scanning electron microscope, atomic force microscopy, root mean square, and dynamic mechanical thermal analysis. EPDM‐g‐MAH showed more potential in enhancing dispersion of the clay nanolayers and their interaction with rubber phases. More potential for separating and dispersing the clay nanoplatelets with better interface enhancement was exhibited by EPDM‐g‐MAH as compatibilizer. This was consistent with higher resistance towards large strain cyclic deformations along with more heat build‐up characteristics showed by EPDM‐g‐MAH based nanocomposites especially at compatibilizer/organoclay ratio of 3. Pronounced non‐terminal behavior within low frequency region was also observed for melt storage modulus of this nanocomposite, indicating higher extent of intercalation/exfoliation microstructure with reinforced interfaces than the nanocomposite generated by ENR50. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Influence of the clay modification and compatibilizer on the structure and mechanical properties of ethylene–propylene–diene rubber/montmorillonite composites

Ethylene–propylene–diene rubber (EPDM)/montmorillonite (MMT) composites were prepared through a melt process, and three kinds of surfactants with different ammonium cations were used to modify MMT and affect the morphology of the composites. The morphology of the composites depended on the alkyl ammonium salt length, that is, the hydrophobicity of the organic surfactants. Organophilic montmorillonite (OMMT), modified by octadecyltrimethyl ammonium salt and distearyldimethyl ammonium salt, was intercalated and partially exfoliated in the EPDM matrix, whereas OMMT modified by hexadecyltrimethyl ammonium chloride exhibited a morphology in which OMMT existed as a common filler. Ethylene–propylene–diene rubber grafted with maleic anhydride (MAH‐g‐EPDM) was used as a compatibilizer and greatly affected the dispersion of OMMT. When OMMTs were modified by octadecyltrimethyl ammonium chloride and distearydimethyl ammonium chloride, the EPDM/OMMT/MAH‐g‐EPDM composites (100/15/5) had an exfoliated structure, and they showed good mechanical properties and high dynamic moduli. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 638–646, 2004     

Exfoliation targeted toughness enhancement in polypropylene‐blend‐ montmorillonite nanocomposites

BACKGROUND: Both exfoliated and toughened polypropylene‐blend‐montmorillonite (PP/MMT) nanocomposites were prepared by melt extrusion in a twin‐screw extruder. Special attention was paid to the enhancement of clay exfoliation and toughness properties of PP by the introduction of a rubber in the form of compatibilizer toughener: ethylene propylene diene‐based rubber grafted with maleic anhydride (EPDM‐g‐MA). RESULTS: The resultant nanocomposites were characterized using X‐ray diffraction, atomic force microscopy, scanning electron microscopy, thermogravimetric analysis, dynamic mechanical analysis and Izod impact testing methods. It was found that the desired exfoliated nanocomposite structure could be achieved for all compatibilizer to organoclay ratios as well as clay loadings. Moreover, a mechanism involving a decreased size of rubber domains surrounded with nanolayers as well as exfoliation of the nanolayers in the PP matrix was found to be responsible for a dramatic increase in impact resistance of the nanocomposites. CONCLUSION: Improved thermal and dynamic mechanical properties of the resultant nanocomposites promise to open the way for highly toughened super PPs via nanocomposite assemblies even with very low degrees of loading. Copyright © 2008 Society of Chemical Industry     

Functionalization of ethylene–propylene–diene monomer rubber with maleic anhydride in the melt state through high‐shear stress‐induced initiation

The functionalization reactions of ethylene–propylene–diene monomer rubber (EPDM) with maleic anhydride (MAH) in melt state through high‐shear‐stress‐induced initiation by an increase in the screw rotation speed of the twin‐screw extruder and through compounded initiation by the addition of some initiator and an increase in the screw rotation speed were investigated. The results show that, with increasing screw rotation speed and reaction temperature, the percentage grafting and melt flow rate of the functionalized products (EPDM‐g‐MAH) were noticeably increased, and the viscosity‐average molecular weight decreased, which implied that the grafting reaction consisted of the chain scission and grafting reaction of the produced macroradicals with MAH. In the presence of a certain peroxide initiator, the crosslinking reaction during melt extrusion was suppressed by an increase in the screw rotation speed. The percentage grafting of EPDM‐g‐MAH amounted to 1.1%, its melt flow rate was between 0.3 and 4.0 g/10 min, and its gel content was less than 1.0%, depending on the screw rotation speed and reaction temperature. Impact testing and scanning electron microscopy showed that the functionalized product prepared through the high shear stress‐induced initiation had a higher blocking activity with the amide terminated of PA66 than that prepared through the peroxide initiation or through the compound initiation, and the impact strength of the PA66/EPDM blends, improved by the high‐shear‐stress‐induced product was noticeably higher than those of the peroxide‐initiated product or the compound‐initiated one. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

In situ dynamic vulcanization process in preparation of electrically conductive PP/EPDM thermoplastic vulcanizate/expanded graphite nanocomposites: Effects of state of cure

In situ melt dynamic vulcanization process has been employed to prepare electrically conductive polypropylene (PP)/ethylene–propylene–diene rubber (EPDM) (40/60 wt %) thermoplastic vulcanizates (TPVs) incorporated by expanded graphite (EG) as a conductive filler. Maleic anhydride grafted PP (PP‐g‐MAH) was used as compatibilizer and a sulfur curing system was designed and incorporated to vulcanize the EPDM phase during mixing process. Developed microstructures were characterized using scanning electron microscopy (SEM), melt rheomechanical spectroscopy (RMS), X‐ray diffraction (XRD), and transmission electron microscopy (TEM) and were correlated with electrical conductivity behavior. For comparison, another class of TPV/EG nanocomposites was fabricated using a commercially available PP/EPDM‐based TPV via both direct and masterbatch melt mixing process. Conductivity of the nanocomposites prepared by in situ showed no significant change during dynamic vulcanization till the mixing torque reached to the stationary level where micro‐morphology of the cured rubber droplets was fully developed, and conductivity abrupt was observed. In situ cured nanocomposites showed higher insulator to conductor transition threshold (3.15 vol % EG) than those based on commercially available TPV. All electrically conductive in situ prepared TPV nanocomposites exhibited reinforced melt elasticity with pseudosolid‐like behavior within low frequency region in dynamic melt rheometry indicating formation of physical networks by both EG nanolayers and crosslinked EPDM droplets. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

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     

Preparation of interfacially compatibilized PP‐EPDM thermoplastic vulcanizate/graphite nanocomposites: Effects of graphite microstructure upon morphology,electrical conductivity,and melt rheology

Electrically conductive PP/EPDM dynamically crosslinked thermoplastic vulcanizate (TPV)/expanded graphite (EG) has been successfully prepared via melt compounding of maleic anhydride grafted polypropylene (PP‐g‐MA)/EG masterbatch and a commercially available TPV material. Correlation between graphite microstructure, and electrical conductivity as well as melt rheological behavior has been studied. Natural graphite flake (NGF), graphite intercalated compound (GIC), and exfoliated graphite (EG) have been employed and compared. Scanning electron microscopy (SEM) showed the presence of 100–200 nm nanolayers in the structure of PP‐g/EG masterbatches, whereas thinner platelets (1.5–2.5 nm) were revealed by transmission electron microscopy (TEM). Better dispersion of the graphite nanolayers in the microstructure of TPV/PP‐g‐MA/EG composite was verified, as the 7.3 Å spacing between the aggregated graphite nanolayers could not be observed in the XRD pattern of this material. TPV/PP‐g/EG nanocomposites exhibited much lower conductivity percolation threshold (φ_c) with increased conductivity to 10^?5 S/cm at EG wt % of 10. Higher nonlinear and nonterminal melt rheological characteristics of dynamic elastic modulus (G′) at low frequency region was presented by the TPV/PP‐g/EG nanocomposites, indicating the formation of nanoscopic conducting multiple networks throughout the continuous TPV matrix. Maleated PP was found to be much more effective in separating EG nanolayers which is attributed to the higher interfacial interaction between PP‐g‐MAH and EG, synergized with its multiporous structure. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Effects of EPDM‐g‐MAH compatibilizer and internal mixer processing parameters on the properties of NR/EPDM blends: An analysis using response surface methodology

This study evaluates the effects of ethylene‐propylene‐diene‐monomer grafted maleic anhydride (EPDM‐g‐MAH) and internal mixer melt compounding processing parameters on the properties of natural rubber/ethylene‐propylene‐diene rubber (NR/EPDM) blends. Using Response Surface Methodology (RSM) of 2⁵ two‐level fractional factorial, we studied the effects of NR/EPDM ratio, mixing temperature, Banbury rotor speed, mixing period, and EPDM‐g‐MAH contents in NR/EPDM blends. The study found that the presence of EPDM‐g‐MAH in NR/EPDM blends had a predominant role as a compatibilizing agent, which affected the processability and properties of the final material. We also determined the model fitting with constant determination, R² of 99.60% for tensile strength (TS) response with a suggested combination of mixing process input parameters. The reproducibility of the proposed mixing strategy was then confirmed through model validation with a minor deviation at +2.303% and higher desirability of 0.960. This study is essential in providing a process design reference for NR/EPDM blends preparation by melt‐blending and the role of a compatibilizer from the systematic Design of Experiment (DOE) approach. The experimental findings were further supported with swelling and cross‐link density measurements, differential scanning calorimetry analysis, and observation of fracture morphology using a scanning electron microscope. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42199.     

Investigation of crystallization behavior in dynamically vulcanized EPDM–nylon copolymer blends

A thermoplastic vulcanizate (TPV) of a ethylene–propylene–diene terpolymer (EPDM) and nylon copolymer (PA) was prepared by dynamic vulcanization. Maleic anhydride (MAH)–grafted EPDM (EPDM–g–MAH), MAH‐grafted EPR (EPR–g–MAH), and chlorinated polyethylene (CPE) were used as compatibilizers. The effect of dynamic vulcanization and compatibilizer on the crystallization behavior of PA was investigated. Differential scanning calorimeter measurement results showed no pronounced shift in the crystallization temperature for PA in EPDM–PA TPV compared to that for PA in the neat state, whereas the crystallization temperature increased after adding compatibilizer. The decrease in the crystallinity of TPVs was a result of the crystallization occurring in confined spaces between rubber particles. The equilibrium melting temperature (Tm⁰) of the PA copolymer was measured and was determined to be 157°C. The isothermal crystallization kinetics of PA in the neat and TPV states also was investigated. The crystallization rate was highest in the compatibilized TPV and lowest in the neat PA, whereas it was intermediate in the uncompatibilized TPV unvulcanized blends. Compared with unvulcanized EPDM–PA blends, the dynamic vulcanization process seemed to cause an obvious increase in the crystallization rate of the PA copolymer, especially when a suitable compatibilizer was used. This occurred because the dynamic vulcanization introduced fine crosslinked rubber particles that could act as heterogeneous nucleating centers. In addition, the use of a suitable compatibilizer permitted the formation of finely dispersed vulcanized rubber particles and therefore increased the density of the nucleating centers. The complex morphology of the blends was investigated by atomic force microscopy to evaluate the effect of compatibilizer on the size of the dispersed rubber particles. Compared with the morphology of TPVs with the same dosage of EPDM–g–MAH compatibilizer, the morphology of TPVs using EPR–g–MAH as compatibilizer showed much smaller dispersed rubber particles, which may have contributed to the higher crystallization rate. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 824–829, 2003     

Polyamide 6/maleated ethylene–propylene–diene rubber/organoclay composites with or without glycidyl methacrylate as a compatibilizer

Polyamide 6 (PA6)/maleated ethylene–propylene–diene rubber (EPDM‐g‐MA)/organoclay (OMMT) composites were melt‐compounded through two blending sequences. Glycidyl methacrylate (GMA) was used as a compatibilizer for the ternary composites. The composite prepared through via the premixing of PA6 with OMMT and then further melt blending with EPDM‐g‐MA exhibited higher impact strength than the composite prepared through the simultaneous blending of all the components. However, satisfactorily balanced mechanical properties could be achieved by the addition of GMA through a one‐step blending sequence. The addition of GMA improved the compatibility between PA6 and EPDM‐g‐MA, and this was due to the reactions between PA6, EPDM‐g‐MA, and GMA, as proved by Fourier transform infrared analysis and solubility (Molau) testing. In addition, OMMT acted as a compatibilizer for PA6/EPDM‐g‐MA blends at low contents, but it weakened the interfacial interactions between PA6 and EPDM‐g‐MA at high contents. Both OMMT and GMA retarded the crystallization of PA6. The complex viscosity, storage modulus, and loss modulus of the composites were obviously affected by the addition of OMMT and GMA. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Interfacially compatibilized poly(lactic acid) and poly(lactic acid)/polycaprolactone/organoclay nanocomposites with improved biodegradability and barrier properties: Effects of the compatibilizer structural parameters and feeding route

Nanocomposites with enhanced biodegradability and reduced oxygen permeability were fabricated via melt hybridization of organomodified clay and poly (lactic acid) (PLA) as well as a PLA/polycaprolactone (PCL) blend. The nanocomposite microstructure was engineered via interfacial compatibilization with maleated polypropylene (PP‐g‐MA). Effects of the compatibilizer structural parameters and feeding route on the dispersion state of the nanolayers and their partitioning between the PLA and PCL phases were evaluated with X‐ray diffraction, transmission electron microscopy, and scanning electron microscopy. Although highly functionalized PP‐g‐MA with a low molecular weight was shown to be much more effective in the intercalation of PLA and the PLA/PCL blend into the clay gallery spaces, composite samples compatibilized by high‐molecular‐weight PP‐g‐MA with a lower degree of maleation exhibited lower oxygen permeability as well as a higher rate of biodegradation, which indicated the accelerating role of the dispersed nanolayers and their interfaces in the enzymatic degradation of PLA and PLA/PCL matrices. This evidenced a correlation between the nanocomposite structure and rate of biodegradation. The size of the PCL droplets in the PLA matrix was reduced by nanoclay incorporation, and this revealed that the nanolayers were preferentially wetted by PCL in the blend. However, PCL appeared as fine and elongated particles in the microstructure of the PLA/PCL/organoclay hybrids compatibilized by higher molecular weight and less functionalized PP‐g‐MA. All the PLA/organoclay and PLA/PCL/organoclay hybrids compatibilized with high‐molecular‐weight PP‐g‐MA displayed a higher dynamic melt viscosity with more pseudo solid‐like melt rheological responses, and this indicated the formation of a strong network structure by the dispersed clay layers. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

The effect of clay dispersion on the properties of LLDPE/LLDPE‐g‐MAH/montmorillonite nanocomposites

In this work, three coupling agents presenting different grafting contents and molecular weights were used to prepare linear low density polyethylene (LLDPE)/linear low density polyethylene grafted with maleic anhydride (LLDPE‐g‐MAH)/montmorillonite nanocomposites with various morphologies. The clay dispersion was analyzed at the micrometric level by scanning electron microscopy and at the nanometric level by X‐ray diffraction (XRD) and transmission electron microscopy (TEM). It was found that coupling agents having intermediate molecular weights led to the highest exfoliation extents, whereas the coupling agent presenting the highest molecular weight led to a poor delamination of the clay platelets. The properties of the nanocomposites produced and of their LLDPE/LLDPE‐g‐MAH reference blends were analyzed. It was shown that the best improvements in mechanical and barrier properties are not necessarily achieved for the nanocomposites, exhibiting the highest exfoliation extents. The length of the tactoids also plays a crucial role on the macroscopic properties. In addition, a high level of delamination could result in a loss of reinforcement effect, due to the inherent flexibility of the individual clay platelets. Finally, the strength of the clay/polymer interface, which was evaluated through surface tension measurements, seems to play a significant role on the properties of the nanocomposites. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers.     

Effects of clay contents on the dynamic mechanical and rheological properties of polypropylene/MAH‐g‐POE/clay composites

A series of polypropylene/maleic anhydride grafted polypropylene octane elastomer (MAH‐g‐POE)/clay (PPMC) nanocomposites were prepared with a novel compatilizer MAH‐g‐POE and different contents of octadecyl amine modified montmorillonite, and the effects of clay contents on the dynamic mechanical and rheological properties of these PPMC composites were investigated. With clay content increasing, the characteristic X‐ray diffraction peak changed from one to two with intensity decreasing, indicating the decreasing concentration of the intercalated clay layers. The gradual decrease of crystallization temperature of PPMC composites with the increase of clay loading should be attributed to the preferred intercalation of MAH‐g‐POE molecules into clay interlayer during blending, which is also reflected by scanning electron microscopy observations. By evaluating the activation energy for the glass transition process of MAH‐g‐POE and polypropylene (PP) in the PPMC composites, it is found that clay intercalation could cause the restriction effect on the glass transition of both MAH‐g‐POE and PP, and this restriction effect appears stronger for PP and attained the highest degree at 5 wt % clay loading. The melt elasticity of PP could be improved apparently by the addition of MAH‐g‐POE, and 5 wt % clay loading is enough for further enhancing the elastic proportion of PP. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Compatibilizing effect of ethylene–propylene–diene grafted maleic anhydride terpolymer on the blend of polyamide 66 and thermal liquid crystalline polymer

Polyamide 66–thermal liquid crystalline polymer (PA66/TLCP) composites containing 10 wt% TLCP was compatibilized by ethylene–propylene–diene‐grafted maleic anhydride terpolymer (MAH‐g‐EPDM). The blending was performed on a twin‐screw extrusion, followed by an injection molding. The rheological, dynamic mechanical analysis (DMA), thermal, mechanical properties, as well as the morphology and FTIR spectra, of the blends were investigated and discussed. Rheological, DMA, and FTIR spectra results showed that MAH‐g‐EPDM is an effective compatibilizer for PA66/TLCP blends. The mechanical test indicated that the tensile strength, tensile elongation, and the bending strength of the blends were improved with the increase of the content of MAH‐g‐EPDM, which implied that the blends probably have a great frictional shear force, resulting from strong adhesion at the interface between the matrix and the dispersion phase; while the bending modulus was weakened with the increase of MAH‐g‐EPDM content, which is attributed to the development of the crystalline phase of PA66 hampered by adding MAH‐g‐EPDM. POLYM. COMPOS., 27:608–613, 2006. © 2006 Society of Plastics Engineers     

A spectroscopic approach for structural characterization of polypropylene/clay nanocomposite

This study focuses on the degree of dispersion and structural development of organomodified MMT clay (OMMT) during processing of polypropylene clay nanocomposites using both conventional and nonconventional characterization techniques. PP‐g‐MA and Cloisite 15A were melt blended with three different grades of PP separately in a micro‐twin screw compounder at selected screw speed and temperature. The clay was modified with fluorescent dyes and the adsorbed dye content in the clay gallery was estimated by using UV‐spectrophotometric method. The effects of residence time and molecular weight of the PP matrix on the clay dispersion were studied. The extent of dispersion and exfoliation of the clay in polymer matrix determined from the torque versus time data obtained from microcompounder. It was further supported by XRD, SEM, TEM, and DSC analysis. Offline dielectric and fluorescence spectrophotometric studies were also carried out. Changes in dielectric constant and dielectric loss with both frequency and temperature yielded quantitative information about the extent of clay exfoliation and intercalation in the polymer matrix. It was observed that with an increase in MFI (decrease in molecular weight) and mixing time, the extent of clay dispersion and exfoliation were also improved due to easy diffusion of polymer chains inside clay gallery. POLYM. COMPOS., 31:2007–2016, 2010. © 2010 Society of Plastics Engineers     

Studies on mechanical and morphological behavior of hybrid nanoclay‐reinforced EPDM‐g‐TMEVS/PS blends

A new copolymer of tris(2‐methoxyethoxy) vinylsilane (TMEVS)‐grafted ethylene–propylene–diene elastomer (EPDM‐g‐TMEVS) has been developed by grafting of TMEVS onto EPDM by using dicumylperoxide (DCP) initiator. The linear polystyrene blends (EPDM‐g‐TMEVS/PS) based on EPDM‐g‐TMEVS have been synthesized with varying weight percentages of polystyrene in a twin‐screw extruder. In a similar manner, the dynamically vulcanized and nanoclay‐reinforced polystyrene blends have also been developed using DCP and organically modified montmorillonite clay separately by means of a twin‐screw extruder. The grafting of TMEVS onto EPDM at allylic position present in the third monomer of EPDM has been confirmed by Fourier Transform infrared spectroscopy. The effect of silane‐grafted EPDM and concentration of nanoclay on mechanical properties of polystyrene blends has been studied as per ASTM standards. The morphological behavior of these blends has been investigated using scanning electron microscope. It was observed that the incorporation of silane‐grafted EPDM enhanced the impact strength and the percentage elongation of linear‐ and dynamically vulcanized blends. However, the values of tensile strength, flexural strength, flexural modulus, and hardness of the blends were found to be decreasing with the increase of silane‐grafted EPDM. In the case of nanoclay‐reinforced polystyrene blends, the values of impact strength, tensile strength, flexural strength, flexural modulus, and hardness were increased with an increase in the concentration of nanoclay. XRD studies have been carried out to confirm the formation of nanoclay‐reinforced EPDM‐g‐TMEVS/PS blends. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Toughening of PP/EPDM blend by compatibilization

To improve the mechanical properties of blends of polypropylene (PP) and terpolymer of ethylene–propylene–diene (EPDM), a triblock copolymer, (PP‐g‐MAH)‐co‐[PA‐6,6]‐co‐(EPDM‐g‐MAH), was synthesized by coupling reaction of maleic anhydride (MAH)‐grafted PP (PP‐g‐MAH), EPDM‐g‐MAH, and PA‐6,6. The newly prepared block copolymer brought about a physical interlocking between the blend components, and imparted a compatibilizing effect to the blends. Introducing the block copolymer to the blends up to 5 wt % lead to formation of a β‐form crystal. The wide‐angle X‐ray diffractograms measured in the region of 2θ between 10° and 50° ascertained that incorporating the block copolymer gave a new peak at 2θ = 15.8°. The new peak was assigned to the (300) plane spacings of the β‐hexagonal crystal structure. In addition, the block copolymer notably improved the low‐temperature impact property of the PP/EPDM blends. The optimum usage level of the compatibilizer proved to be 0.5 wt %. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1267–1274, 2000     

Effect of EPDM‐g‐MAH on the morphology and properties of PA6/EPDM/HDPE ternary blends

The formation of core‐shell morphology within the dispersed phase was studied for composite droplet polymer‐blend systems comprising a polyamide‐6 matrix, ethylene‐propylene‐diene terpolymer (EPDM) shell and high density polyethylene (HDPE) core. In this article, the effect of EPDM with different molecular weights on the morphology and properties of the blends were studied. To improve the compatibility of the ternary blends, EPDM was modified by grafting with maleic anhydride (EPDM‐g‐MAH). It was found that core‐shell morphology with EPDM‐g‐MAH as shell and HDPE as core and separated dispersion morphology of EPDM‐g‐MAH and HDPE phase were obtained separately in PA6 matrix with different molecular weights of EPDM‐g‐MAH in the blends. DSC measurement indicated that there may be some co‐crystals in the blends due to the formation of core‐shell structure. Mechanical tests showed that PA6/EPDM‐g‐MAH/HDPE ternary blends with the core‐shell morphology exhibited a remarkable rise in the elongation at break. With more perfect core‐shell composite droplets and co‐crystals, the impact strength of the ternary blends could be greatly increased to 51.38 kJ m^?2, almost 10 times higher than that of pure PA6 (5.50 kJ m^?2). POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers