Microstructural characteristics of glass bead‐ and wollastonite‐filled isotactic‐polypropylene composites modified with thermoplastic elastomers

Microstructural characteristics of isotactic‐polypropylene/glass bead (iPP/GB) and iPP/wollastonite (iPP/W) composites modified with thermoplastic elastomers, poly(styrene‐b‐ethylene‐co‐butylene‐b‐styrene) copolymer (SEBS) and corresponding block copolymer grafted with maleic anhydride (SEBS‐g‐MA), were investigated. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and dynamic mechanical analyses (DMA) showed that the iPP/SEBS and iPP/SEBS‐g‐MA blends were partially compatible two‐phase systems. Well‐dispersed spherical GB and acicular W particles without evidence of interfacial adhesion were observed in the iPP/GB and iPP/W binary composites respectively. Contrary to the blends, melt flow rates of the iPP/GB and PP/W composites decreased more with SEBS‐g‐MA than with SEBS because of enhanced interfacial adhesion with SEBS‐g‐MA elastomer. The SEM analyses showed that the ternary composites containing SEBS exhibited separate dispersion of the rigid filler and elastomer particles (i.e., separate microstructure). However, SEBS‐g‐MA elastomer not only encapsulated the spherical GB and acicular W particles completely with strong interfacial adhesion (i.e., core‐shell microstructure) but also dispersed separately throughout iPP matrix. In accordance with the SEM observations, the DSC and DMA revealed quantitatively that the rigid filler and SEBS particles in iPP matrix acted individually, whereas the rigid filler particles in the ternary composites containing SEBS‐g‐MA acted like elastomer particles because of the thick elastomer interlayer around the filler particles. The Fourier transform infrared analyses revealed an esterification reaction inducing the strong interfacial adhesion between the SEBS‐g‐MA phase and the filler particles. POLYM. COMPOS., 31:1265–1284, 2010. © 2009 Society of Plastics Engineers     

Mechanical properties of glass bead‐ and wollastonite‐filled isotactic‐polypropylene composites modified with thermoplastic elastomers

Mechanical properties of the isotactic‐polypropylene/glass bead (iPP/GB) and iPP/wollastonite (iPP/W) composites modified with thermoplastic elastomers, the poly(styrene‐b‐ethylene‐co‐butylene‐b‐styrene) copolymer (SEBS) and corresponding block copolymer grafted with maleic anhydride (SEBS‐g‐MA), were investigated. An increase in toughness of iPP with the elastomers was associated with a decrease in rigidity and strength. Mechanical performance of iPP increased more with acicular W than with spherical GB due to reinforcing effect of W. Comparing the (iPP/GB)/SEBS and (iPP/W)/SEBS composites having the separate microstructure, strength and toughness values of the iPP/GB and iPP/W composites increased more with SEBS‐g‐MA at the expense of rigidity due to the core‐shell microstructure with strong interfacial adhesion. Moreover, the iPP/W composite exhibited superior mechanical performance with 2.5 and 5 vol% of SEBS‐g‐MA because of a positive synergy between the core‐shell microstructure and reinforcing effect of acicular W. The extended models revealed that the elastomer and filler particles in the (iPP/GB)/SEBS and (iPP/W)/SEBS composites acted individually due to the separate microstructure. However, the rigid GB and W particles encapsulated with the thick elastomer interlayer (R₀/R₁ = 0.91) in the (iPP/GB)/SEBS‐g‐MA and (iPP/W)/SEBS‐g‐MA composites acted like neither big elastomer particles nor like individual rigid particles, inferring more complicated failure mechanisms in the core‐shell composites. POLYM. COMPOS., 31:1285–1308, 2010. © 2010 Society of Plastics Engineers     

Phase structure and morphology of wollastonite‐reinforced polypropylene composites modified with SEBS and SEBS‐g‐MA elastomers

Supermolecular structure of isotactic polypropylene/wollastonite/styrenic rubber block copolymers composites were studied as a function of elastomeric poly‐ (styrene‐b‐ethylene‐co‐butylene‐b‐styrene) triblock copolymer (SEBS) and the SEBS grafted with maleic anhydride (SEBS‐g‐MA) content (from 0 to 20 vol%) by optical, scanning, and transmission electron microscopy, wide‐angle X‐ray diffraction and differential scanning calorimetry. Wollastonite particles disturbed the spherulitization of polypropylene matrix. Both elastomers affected the crystallization of polypropylene matrix mainly by solidification effect. Although SEBS‐g‐MA encapsulated wollastonite particles more expressive than SEBS forming thus core‐shell morphology in higher extent, scanning electron micrographs indicated more constrained wollastonite particles in fractured surfaces of composites with SEBS elastomer. Moreover, SEBS‐g‐MA disorientated wollastonite particles and affected reorientation of the polypropylene crystallites stronger than SEBS elastomer. POLYM. ENG. SCI., 47:2145–2154, 2007. © 2007 Society of Plastics Engineers     

Effects of carbon nanofibers on the fracture,mechanical, and thermal properties of PP/SEBS‐g‐MA blends

Polypropylene/maleated (styrene‐ethylene‐butadiene‐styrene) (PP/SEBS‐g‐MA) blends reinforced with 0.2–2.5 wt% carbon nanofibers (CNFs) were prepared by injection molding. The structure, thermal, mechanical, and fracture behaviors of PP/SEBS‐g‐MA blends and their nanocomposites were studied. Wide‐angle X‐ray diffraction (WAXD) results showed that the SEBS‐g‐MA and/or CNF additions do not induce a structural change of PP. Tensile measurements showed that the Young's modulus and tensile yield strength increase with the increasing filler content. Izod impact and essential work of fracture test results demonstrated that CNFs are beneficial to improve the impact strength and specific essential work of fracture of PP/SEBS‐g‐MA blends. Therefore, tough PP‐nanocomposites can be achieved by melt‐blending low fractions of CNFs and appropriate elastomer contents. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Process–structure–property relationship in ternary short‐glass‐fiber/elastomer/polypropylene composites

Short‐glass‐fiber (SGF)‐reinforced polypropylene (PP) composites toughened with a styrene/ethylene butylene/styrene (SEBS) triblock copolymer were injection molded after extrusion. Furthermore, a maleic anhydride (MA)‐grafted SEBS copolymer (SEBS‐g‐MA) was used as an impact modifier and compatibilizer. The effects of the processing conditions and compatibilizer on the microstructure and tensile and impact performance of the hybrid composites were investigated. In the route 1 fabrication process, SGF, PP, and SEBS were blended in an extruder twice, and this was followed by injection molding. In route 2, or the sequential blending process, the elastomer and PP were mixed thoroughly before the addition of SGF. In other words, either PP and SEBS or PP and SEBS‐g‐MA pellets were premixed in an extruder. The produced pellets were then blended with SGF in the extruder, and this was followed by injection molding. The SGF/SEBS‐g‐MA/PP hybrid fabricated by the route 2 process exhibited the highest modulus, yield stress, tensile stress at break, Izod impact energy, and Charpy drop weight impact strength among the composites investigated. This was due to the formation of a homogeneous SEBS elastomeric interlayer at the SGF and matrix interface of the SGF/SEBS‐g‐MA/PP hybrid. This SEBS rubbery layer enhanced the interfacial bonding between SGF and the matrix of the SGF/SEBS‐g‐MA/PP hybrid. The correlations between the processing, microstructure, and properties of the hybrids were investigated. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1384–1392, 2003     

Influences of compatibilizers on rheology and mechanical properties of propylene random copolymer/styrene‐ethylene‐butylene‐styrene block copolymer/organic‐montmorillonite nanocomposites

Propylene random copolymer (PPR)/styrene‐ethylene‐butylene‐styrene block copolymer (SEBS)/compatibilizer/organic‐montmorillonite (OMMT) quaternary nanocomposites and PPR/compatibilizer/OMMT ternary nanocomposites were prepared via two‐stage melt blending and influences of compatibilizers, maleic anhydride (MA) grafted styrene‐ethylene‐butylene‐styrene copolymer (SEBS‐g‐MA), poly(octene‐co‐ethylene) (POE‐g‐MA), or propylene block copolymers (PPB‐g‐MA), on rheology and mechanical properties of the nanocomposites were investigated. The results of X‐ray diffraction measurement and transmission electron microscopy observation showed that OMMT layers were mainly intercalated in the nanocomposites except for the mainly exfoliated structure in the quaternary nanocomposites using POE‐g‐MA as compatibilizer. The nanocomposites exhibited pseudo‐solid like viscoelasticity in low frequencies and shear‐thinning in high shear rates. As far as OMMT dispersion was concerned, POE‐g‐MA was superior to SEBS‐g‐MA and PPB‐g‐MA, which gives rise to the highest viscosities in both the ternary and quaternary nanocomposites. The quaternary nanocomposites containing POE‐g‐MA were endowed with balanced toughness and rigidity. It was suggested that a suitable combination of compatibilizer and SEBS was an essentially important factor for adjusting the OMMT dispersion and distribution, the rheological and mechanical performances of the nanocomposites. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Tensile deformation mechanisms of polypropylene/elastomer blends reinforced with short glass fiber

Polypropylene hybrid composites reinforced with short glass fiber (SGF) and toughened with styrene–ethylene butylenes–styrene (SEBS) elastomer were prepared using extrusion and injection‐molding techniques. Moreover, hybrids compatibilized with SEBS‐grafted maleic anhydride (SEBS‐g‐MA) and hybrid compatibilized with PP grafted with maleic anhydride (PP‐g‐MA) were also fabricated. The matrix of the latter hybrid was designated as mPP and consisted of 95% PP and 5% PP‐g‐MA. Tensile dilatometry was carried out to characterize the fracture mechanisms of hybrid composites. Dilatometric responses showed that the elastic deformation was the dominant deformation mechanism for the SGF/SEBS/PP and SGF/SEBS‐g‐MA/PP hybrids. However, cavitation deformation prevailed over shearing deformation for both hybrids at the higher strain regime. The cavitation strain resulted from the debonding of glass fibers and from the crazing of the matrix in the SGF/SEBS/PP hybrid. In contrast, the cavitation was caused by the debonding of SEBS particles from the matrix of the SGF/SEBS‐g‐MA/PP hybrid. The use of PP‐g‐MA resulting in elastic deformation was the main mode of deformation in the low‐strain region for the SGF/SEBS/mPP and SEBS/SEBS‐g‐MA/mPP hybrids; thereafter, shearing appeared to dominate at the higher strain regime. This was attributed to the MA functional group improving the bonding between the SGF and PP. The correlation between fracture morphology and dilatometric responses also is presented in the article. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 441–451, 2003     

Preparation and performance characteristics of short‐glass‐fiber/maleated styrene–ethylene–butylene–styrene/polypropylene hybrid composites

Eighty/twenty polypropylene (PP)/styrene–ethylene–butylene–styrene (SEBS) and 80/20 PP/maleated styrene–ethylene–butylene–styrene (SEBS‐g‐MA) blends reinforced with 30 wt % short glass fibers (SGFs) were prepared by extrusion and subsequent injection molding. The influence of the maleic anhydride (MA) functional group grafted to SEBS on the properties of SGF/SEBS/PP hybrid composites was studied. Tensile and impact tests showed that the SEBS‐g‐MA copolymer improved the yield strength and impact toughness of the hybrid composites. Extensive plastic deformation occurred at the matrix interface layer next to the fibers of the SGF/SEBS‐g‐MA/PP composites during impact testing. This was attributed to the MA functional group, which enhanced the adhesion between SEBS and SGF. Differential scanning calorimetry measurements indicated that SEBS promoted the crystallization of PP spherulites by acting as active nucleation sites. However, the MA functional group grafted to SEBS retarded the crystallization of PP. Finally, polarized optical microscopy observations confirmed the absence of transcrystallinity at the glass‐fiber surfaces of both SGF/SEBS/PP and SGF/SEBS‐g‐MA/PP hybrid composites. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1303–1311, 2002     

Morphology and flame‐retardancy properties of ternary high‐impact polystyrene/elastomer/polystyrene‐encapsulated magnesium hydroxide composites

The effects of elastomer type on the morphology, flammability, and mechanical properties of high‐impact polystyrene (HIPS)/polystyrene (PS)‐encapsulated magnesium hydroxide (MH) were investigated. The ternary composites were characterized by cone calorimetry, mechanical testing, and scanning electron microscopy. Morphology was controlled with poly[styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene] (SEBS) triblock copolymer or the corresponding maleinated poly[styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene] (SEBS‐g‐MA). The HIPS/SEBS/PS‐encapsulated MH composites exhibited separation of the filler and elastomer, whereas the HIPS/SEBS‐g‐MA/PS‐encapsulated MH composites exhibited encapsulation of the filler by SEBS‐g‐MA. The flame‐retardant and mechanical properties of the ternary composites were strongly dependent on microstructure. The composites with an encapsulation structure showed higher flame‐retardant properties than those with a separation structure at the optimum use level of SEBS‐g‐MA. Furthermore, the composites with a separation structure showed a higher modulus and impact strength than those with an encapsulation structure. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Mechanical properties of wollastonite‐reinforced polypropylene composites modified with SEBS and SEBS‐g‐MA elastomers

Mechanical properties of isotactic polypropylene/wollastonite/styrene rubber block copolymers (iPP/wollastonite/SRBC) composites were studied as a function of elastomeric poly(styrene‐b‐ethylene‐co‐butylene‐b‐styrene) triblock copolymer (SEBS) and SEBS grafted with maleic anhydride (SEBS‐g‐MA) content from 0 to 20 vol%. Microphase morphology was stronger influenced by SRBC elastomers than by different wollastonite types. Higher encapsulation ability of SEBS‐g‐MA than SEBS caused more expressive core‐shell morphology and consequently higher notched impact strength as well as yield parameters, but lower Young's modulus. Higher ductility of the composites with SEBS than with SEBS‐g‐MA has been primarily caused by better miscibility of the polypropylene chains with SEBS molecules. Surface properties of components and adhesion parameters also indicated that adhesion at SEBS‐g‐MA/wollastonite interface, which was stronger than the one at the SEBS/wollastonite interface, influenced higher encapsulation of wollastonite particles by SEBS‐g‐MA. POLYM. ENG. SCI., 47:1873–1880, 2007. © 2007 Society of Plastics Engineers     

Property enhancement in polypropylene ternary blend nanocomposites via a novel poly(ethylene oxide)‐grafted polystyrene‐block‐poly(ethylene/butylene)‐block‐polystyrene toughener–compatibilizer system

Synthesis and characterization of a novel toughener–compatibilizer for polypropylene (PP)–montmorillonite (MMT) nanocomposites were conducted to provide enhanced mechanical and thermal properties. Poly(ethylene oxide) (PEO) blocks were synthetically grafted onto maleic anhydride‐grafted polystyrene‐block‐poly(ethylene/butylene)‐block‐polystyrene (SEBS‐g‐MA). Special attention was paid to emphasize the effect of PEO‐grafted SEBS (SEBS‐g‐PEO) against SEBS‐g‐MA on morphology, static/dynamic mechanical properties and surface hydrophilicity of the resultant blends and nanocomposites. It was found that the silicate layers of neat MMT are well separated by PEO chains chemically bonded to nonpolar SEBS polymer without needing any organophilic modification of the clay as confirmed by X‐ray diffraction and transmission electron microscopy analyses. From scanning electron microscopy analyses, elastomeric domains interacting with MMT layers via PEO sites were found to be distributed in the PP matrix with higher number and smaller sizes than the corresponding blend. As a benefit of PEO grafting, SEBS‐g‐PEO‐containing nanocomposite exhibited not only higher toughness/impact strength but also increased creep recovery, as compared to corresponding SEBS‐g‐MA‐containing nanocomposite and neat PP. The damping parameter of the same nanocomposite was also found to be high in a broad range of temperatures as another advantage of the SEBS‐g‐PEO toughener–compatibilizer. The water contact angles of the blends and nanocomposites were found to be lower than that of neat hydrophobic PP which is desirable for finishing processes such as dyeing and coating. © 2018 Society of Chemical Industry     

Effect of transfer film on tribological behavior of polyamide 66‐based binary and ternary nanocomposites

BACKGROUND: In a polymer–metal sliding system, the formation and performance of the transfer film have important effects on the tribological behavior of the polymer. In order to reveal the wear mechanism of polyamide 66 (PA 66) and its composites consisting of styrene–(ethylene/butylene)–styrene triblock rubber grafted with maleic anhydride (SEBS‐g‐MA) particles and organoclay nano‐layers, the tribological behavior and transfer films of polyamide 66 and its composites were investigated under dry sliding. RESULTS: The incorporation of SEBS‐g‐MA rubber particles reduces the wear mass loss of PA 66, while the addition of organoclay nano‐layers increases the wear mass loss. The transfer films formed by neat PA 66 and PA 66/organoclay binary nanocomposite include a dark portion and bright portion. In the dark portion, the transfer film is thicker; in the bright portion, the steel ring surface is exposed. The transfer film formed by PA 66/SEBS‐g‐MA/organoclay ternary nanocomposite is thinner and more uniform than the transfer films formed by the other materials. CONCLUSION: When SEBS‐g‐MA rubber particles and organoclay nano‐layers are added simultaneously to PA 66, the wear resistance of PA 66 can be improved markedly. The main reason is that PA 66/SEBS‐g‐MA/organoclay ternary nanocomposite can form a thin and uniform transfer film on the steel ring surface. Copyright © 2008 Society of Chemical Industry     

Characteristics of impact modified polystyrene/organoclay nanocomposites

The poor impact resistance of Polystyrene (PS) was enhanced by the addition of elastomeric material, SEBS‐g‐MA. To prevent the reduction in strength and stiffness, organoclay Cloisite® 25A was used as filler and introduced into the matrix by a corotating twin screw extruder. Throughout the study, the clay content was kept at 2 wt%, whereas the content of SEBS‐g‐MA was varied between 5 and 40 wt%. It was found that Cloisite® 25A displays well dispersion in the ternary nanocomposites and the degree of dispersion increases with the elastomer content. The elastomeric phase has a greater viscosity than pure PS. Thus, as expected, at low elastomer contents, it forms the dispersed phase in the matrix as droplets. Transmission electron microscopy results show that the clay layers reside at the interphase between PS and elastomer and also inside the elastomeric phase. Owing to the location of the clay particles, the average elastomer domain size in ternary nanocomposites are found to be greater than that in the relative binary blends of PS‐(SEBS‐g‐MA). Moreover, with the organoclay addition, phase inversion point shifts to lower elastomer contents. The mechanical test results showed that the nanocomposites containing 15 and 20 wt% SEBS‐g‐MA have the optimum average domain size that results in high‐impact strength values without deteriorating the tensile properties. POLYM. COMPOS., 31:1853–1861, 2010. © 2010 Society of Plastics Engineers.     

Melt rheological properties of PBT/SEBS and reactively compatibilized PBT/SEBS/SEBS‐g‐MA polymer blends

Melt rheological properties of PBT/SEBS and PBT/SEBS/SEBS‐g‐MA blends at SEBS volume fraction (Φ_d) = 0.00–0.38 were studied at 240°C, 250°C and 260°C using a capillary rheometer. The compatibilizer SEBS‐g‐MA addition resulted in significant reduction in the dynamic interfacial tension which in turn led to increased phase adhesion. The power law exponent n decreased with increasing Φ_d and increasing temperature for both the compatiblized and uncompatiblized blends. The consistency index of PBT/SEBS increased with increasing Φ_d but were smaller than those of PBT/SEBS/SEBS‐g‐MA blends. Melt elasticity such as die swell and first normal stress difference increased with Φ_d. Variations of first normal stress coefficient function (ψ₁), recoverable shear strain (γ_R), relaxation time (λ), and shear compliance (J_c) values versus shear rate were analyzed. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41402.     

Dynamic reaction inside co‐rotating twin screw extruder. I. Truck tire model material/polypropylene blends

Waste ground rubber tire (WGRT) is a complex composite containing various elastomers, carbon black, zinc oxide, stearic acid, processing oils, and other curatives. Most of the waste ground rubber tire is composed of mainly natural rubber (NR) and styrene butadiene rubber (SBR) in varying proportions. Blending it with other thermoplastic materials is difficult due to the inherent thermodynamic incompatibility. But, the compatibility can be increased by making the reactive sites in WGRT with suitable chemicals under optimum condition of shearing inside a twin screw extruder and it is said to undergo a dynamic reaction inside the extruder. To understand the mechanism of dynamic reaction process of a rubber/polyolefin blend, the blending of a truck tire model material rubber with polyolefin was first tried before it was applied to waste WGRT material. It was observed that the blends of a truck tire model rubber material and PP thermoplastic are physical mixture of two incompatible polymers in which a continuous plastic phase is largely responsible for the tensile properties. The rubber particles are the dispersed phase. The large particle size and the poor adhesion of these rubber particles are believed to be liable for the poor tensile properties. In case of blends of truck tire model material with isotactic polypropylene the tensile properties are found to be lower than that of its PP‐g‐MA counterpart which can be attributed to the reaction of the MA with the carbon black particles. A schematic representation of the possible interactions has been proposed. The effect of addition of compatibilizers such as SEBS and SEBS‐g‐MA has also been studied. The tensile and TGA studies indicate that the polarity of SEBS and SEBS‐g‐MA induces an increase in the performance characteristics for both types of polyolefins but the intensity of this increase is higher in the PP‐g‐MA based blends. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 106: 3193–3208, 2007     

Ultrasound assisted continuous‐mixing for the preparation of PP/SEBS/OMMT ternary nanocomposites

Polypropylene (PP)/polystyrene‐block‐poly(ethylene‐co‐butylenes)‐block‐polystyrene (SEBS)/organo‐montmorillonite (OMMT) nanocomposites of varying concentrations of maleic anhydride‐grafted polypropylene (PP‐g‐MA) were prepared by continuous mixing assisted by ultrasonic oscillation. The structure and morphology of nanocomposites were investigated by X‐ray diffraction (XRD), transmission electron microscopy, and scanning electron microscopy. It was found that both PP‐g‐MA and ultrasonic oscillation could enhance the intercalation and exfoliation of OMMT in PP matrix. Meanwhile, the formation of PP could be induced by ultrasonic irradiation at a power of more than 540 W. Rheological properties including complex viscosity, storage, and loss modulus of nanocomposites were increased after adding PP‐g‐MA or ultrasonic treatment. The results of mechanical properties showed that PP‐g‐MA could improve the tensile strength and tensile modulus of nanocomposites, but with the sacrifice of impact strength. This problem could be improved by ultrasound due to the reduced particle size of SEBS. However, the mechanical properties would be reduced by ultrasonic treatment with higher intensity due to the polymer degradation. Therefore, the synergistic effect of both compatibilizer and ultrasound should account for the balance between toughness and stiffness of PP/SEBS/OMMT ternary nanocomposites. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41202.     

Study on the microstructures and mechanical behaviour of compatibilized polypropylene/polyamide‐6 blends

A series of blends of polypropylene (PP)–polyamide‐6 (PA6) with either reactive polyethylene–octene elastomer (POE) grafted with maleic anhydride (POE‐g‐MA) or with maleated PP (PP‐g‐MA) as compatibilizers were prepared. The microstructures and mechanical properties of the blends were investigated by means of tensile and impact testing and by scanning electron microscopy and transmission electron microscopy. The results indicated that the miscibility of PP–PA6 blends was improved with the addition of POE‐g‐MA and PP‐g‐MA. For the PP/PA6/POE‐g‐MA system, an elastic interfacial POE layer was formed around PA6 particles and the dispersed POE phases were also observed in the PP matrix. Its Izod impact strength was four times that of pure PP matrix, whilst the tensile strength and Young's modulus were almost unchanged. The greatest tensile strength was obtained for PP/PA6/PP‐g‐MA blend, but its Izod impact strength was reduced in comparison with the pure PP matrix. © 2002 Society of Chemical Industry     

Acid‐modified carbon nanotubes distribution and mechanical enhancement in polystyrene/elastomer blends

The incorporation of carbon nanotubes (CNTs) is expected as an effective path for tailoring mechanical properties of polymer blends. In this study, acid‐modified multiwalled CNTs (A‐MWCNTs) were introduced into polystyrene/maleic anhydride‐g‐(styrene‐ethylene‐butadiene‐styrene) (PS/SEBS‐MA) blends. By altering the mass ratio of PS/SEBS‐MA from 80/20 to 60/40, the biphase structure of blend was changed from sea‐island‐like type to quasi co‐continuous structure, of different mechanical behaviors. In 80/20 mass ratio, the impact strength was improved while the tensile strength was unchanged with increasing A‐MWCNTs content, whereas a simultaneously toughening and strengthening effect was achieved for the compound with 60/40 mass ratio. Scanning electron microscopy, polarized light microscopy, dynamic mechanical analysis, and rheological measurements were carried out to detect the distribution of A‐MWCNTs in the blends. The results demonstrated as increasing the nanotube loading from 0 to 3 wt%, A‐MWCNTs might gradually migrate into continuous PS phase in 80/20 mass ratio, due to the low content of SEBS‐MA, while they were totally packed in SEBS‐MA region within the entire loading range used in 60/40 mass ratio due to its high content of SEBS‐MA. This study provides guidance on the design and preparation of high performance ternary polymer/elastomer/inorganic filler composites. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers     

Evaluation of toughening mechanisms of polypropylene/ethylene–octene copolymer/maleic anhydride‐grafted poly(ethylene‐co‐octene)/clay nanocomposite

The toughness of a polypropylene (PP)/ethylene‐octene copolymer (EOC)/maleic anhydride‐grafted poly(ethylene‐co‐octene) (EOC‐g‐MA)/clay nanocomposite and blends of PP/EOC and PP/EOC/EOC‐g‐MA was investigated using Charpy impact and single‐edge‐notch tensile (SENT) tests. In order to understand the toughening mechanisms, impact fracture surfaces and damage zones of single‐edge‐notch samples were studied with scanning electron microscopy and transmission optical microscopy, respectively. It was observed that the addition of EOC‐g‐MA to PP/EOC blend led to improvements in both impact strength and fracture energy of SENT tests because of the enhanced compatibility of the blend, which resulted from reduced EOC particle size and improved interfacial adhesion, and the decreased crystallinity of PP. The incorporation of clay to PP/EOC/EOC‐g‐MA blend caused a further increase of the toughness, owing to the greater decrease in the size of elastomer particles, to the presence of clay tactoids inside the elastomer phase and presumably to debonding of clay layers during the low‐speed SENT tests. The results of microscopic observations showed that the main toughening mechanism in PP/EOC/EOC‐g‐MA blend and PP/EOC/EOC‐g‐MA/clay nanocomposite is crazing. Copyright © 2012 Society of Chemical Industry     

Relationship between structure and properties in high‐performance PA6/SEBS‐g‐MA/(PPO/PS) blends: The role of PPO and PS

This work aimed at studying the role of poly(phenylene oxide) (PPO) and polystyrene (PS) in toughening polyamide‐6 (PA6)/styrene‐ethylene‐butadiene‐styrene block copolymer grafted with maleic anhydride (SEBS‐g‐MA) blends. The effects of weight ratio and content of PPO/PS on the morphology and mechanical behaviors of PA6/SEBS‐g‐MA/(PPO/PS) blends were studied by scanning electron microscope and mechanical tests. Driving by the interfacial tension and the spreading coefficient, the “core–shell” particles formed by PPO/PS (core) and SEBS‐g‐MA (shell) played the key role in toughening the PA6 blends. As PS improved the distribution of the “core–shell” particles due to its low viscosity, and PPO guaranteed the entanglement density of the PPO/PS phase, the 3/1 weight ratio of PPO/PS supplied the blends optimal mechanical properties. Within certain range, the increased content of PPO/PS could supply more efficient toughening particles and bring better mechanical properties. Thus, by adjusting the weight ratio and content of PPO and PS, the PA6/SEBS‐g‐MA/(PPO/PS) blends with excellent impact strength, high tensile strength, and good heat deflection temperature were obtained. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45281.