Core/shell morphologies in recycled poly(ethylene terephthalate)/linear low-density polyethylene/poly(styrene-<Emphasis Type="Italic">b</Emphasis>-(ethylene-<Emphasis Type="Italic">co</Emphasis>-butylene)-<Emphasis Type="Italic">b</Emphasis>-styrene) ternary blends

Compatibilizer plays very important roles in preparing high performance polymer composites, not only for the ternary immiscible polymer blends, but also for the recycled and reused of waste plastics mixture. Generally, the compatibilizers can be used as the toughening agent in blending polymer materials. In the present work, the poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) or maleic anhydride-grafted poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS-g-MA) acts as the compatibilizer and toughening agent for the preparation of R-PET/LDPE/SEBS (70/20/10) ternary blends. It must be pointed that the ternary blends are costlessly and conveniently prepared from the recycled poly(ethylene terephthalate) (R-PET) and linear low density polyethylene (LLDPE) through a melt blending in a co-rotating twin-screw extruder and injection moulded. The morphologies of the ternary blends are characterized by scanning electron microscopy (SEM). It was found that the blends contains reactive or non-reactive compatibilizer, the morphology originates from the LLDPE particles encapsulated by both SEBS and SEBS-g-MA. So, it results to the reduced interfacial tension between of the R-PET and SEBS-g-MA, in which the grafted chains of PET-g-SEBS-g-MA formed through in situ reaction between R-PET and SEBS-g-MA phases. Therefore, core–shell particles with smaller diameter disperse uniformly in the blends. Moreover, the good compatibilization and corresponding morphologies induce in balanced mechanical and thermal properties. DSC analysis show the dispersed phase particles could act as nucleating agent in the R-PET matrix, which results the improvement of the crystallization temperature. And it was also observed the decreased nucleation activity in graft copolymers in the R-PET/LLDPE/SEBS-g-MA blends. Notched Charpy impact strength and elongation at break are improved by the addition of compatibilizer.     

Optimum toughening via a bicontinuous blending: toughening of PPO with SEBS and SEBS-g-maleic anhydride

The poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) was toughened by melt extrusion through its blending with a styrene-b-ethylene/butadiene-b-styrene triblock copolymer (SEBS), or with maleic anhydride (MA) grafted SEBS (SEBS-g-MA). Their morphology, mechanical properties, and rheology have been investigated. Transmission electron microscopy revealed that both kinds of blends had an island-sea structure at low concentrations of SEBS or SEBS-g-MA and a bicontinuous one at sufficiently high concentrations. However, the percolation threshold was higher for SEBS than for the SEBS-g-MA. The Izod impact strength of PPO could be significantly improved through its blending with SEBS-g-MA, particularly in a blend with 20 wt% of SEBS-g-MA at which it had a maximum value. The rheological experiments indicated that the incorporation of SEBS increased and that of SEBS-g-MA decreased the melt viscosity of the system.     

Influence of morphology on rheological and mechanical properties of SEBS-toughened,glass-bead-filled isotactic polypropene

The influence of morphology of glass-bead-filled isotactic polypropene containing 0–20 vol% thermoplastic elastomers (TPE) on mechanical and rheological properties was investigated. Polystyrene-block-poly(ethene-co-but-1-ene)-block-polystyrene(SEBS) and the corresponding block copolymer grafted with maleic anhydrid (SEBS-g-MA) were used as thermoplastic elastomers, realizing, in the first case, a three-phase morphology with separately dispersed glass beads and SEBS particles. In the second case, SEBS-g-MA forms an elastomeric interlayer between glass beads and polypropene matrix, comprising core–shell particles. Young's modulus and tensile yield stress of the hybrid composites decrease with an increase in TPE volume fraction due to low stiffness and strength of TPE. In comparison with the three-phase morphology of hybrid composites with SEBS, SEBS-g-MA interlayers effect a reduced stiffness of the hybrid composites but improve interfacial adhesion and, thus, tensile yield stress. Rheological storage and loss moduli increase with an increase in glass bead and TPE volume fraction. Due to improved interfacial adhesion, melt elasticity and viscosity are enhanced by the SEBS-g-MA interlayer when compared with separately dispersed SEBS. Consequently, the reduced stiffening effect of the glass beads due to SEBS-g-MA interlayer decreases mechanical elasticity, whereas improved interfacial adhesion, also promoted by the SEBS-g-MA interlayer, enhances tensile yield stress and melt elasticity. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 2499–2506, 1998     

Effect of rubber particle size and rubber type on the mechanical properties of glass fiber reinforced, rubber-toughened nylon 6

The effects of rubber type and particle size on the mechanical properties of glass fiber reinforced blends of nylon 6 and EPR/EPR-gMA or SEBS/SEBS-g-MA were investigated; rubber particle size in the two systems could be controlled by varying the ratio of EPR to EPR-g-MA or SEBS to SEBS-g-MA. Unreinforced materials with the highest levels of toughness did not necessarily lead to the highest fracture energy when reinforced with 15 wt% glass fibers. Materials toughened with SEBS/SEBS-gMA, which are tougher in the absence of glass fibers had lower fracture energies when 15 wt% glass fibers are present. In general, smaller rubber particles led to higher fracture energies. Fracture analysis according to a modified essential work of fracture analysis reveals that SEBS/SEBS-g-MA have high values of the dissipative energy density, u_d, in the absence of glass fibers. When 15 wt% glass fibers are added, u_d is essentially zero for all the materials tested. The limiting specific fracture energy, u₀, on the other hand, was higher for both unreinforced and glass fiber reinforced EPR/EPR-g-MA toughened blends than for SEBS/SEBS-g-MA based materials. Transmission electron microscopy observations of fractured specimens indicate that glass fibers decrease the size of the damage zone of rubber toughened nylon 6. Shear yielding was seen in fractured specimens of reinforced nylon 6 blends containing either SEBS/SEBS-g-MA or EPR-g-MA, but the size of this shear yielded zone was larger for EPR/EPR-g-MA. In addition, EPR/EPR-g-MA based materials displayed craze-like deformations, while SEBS-g-MA materials did not exhibit this deformation process.     

Thermal and crystallisation behaviours of blends of polyamide 12 with styrene-ethylene/butylene-styrene rubbers

Polyamide 12 (PA12)/styrene-ethylene/butylene-styrene (SEBS) and PA12/maleic anhydride grafted SEBS (SEBS-g-MA) blends were prepared in a twin-screw extruder followed by injection moulding. Thermal and crystallisation behaviours of these blends were evaluated. Thermal properties and morphology of the blends were estimated using thermo gravimetric analysis (TGA) and scanning electron microscopy (SEM), respectively. The phase structure of the blends was interpreted by dynamic mechanical thermal analyser (DMTA). In terms of temperature at maximum rate of degradation (T_max) and integral procedural decomposition temperature (IPDT), it was found that PA12/SEBS-g-MA (PM) blends possessed greater thermal stability than PA12/SEBS (PS) blends. The kinetics of degradation process of PA12 and its blends were studied using Coats-Redfern (CR) method. It was found that there is no appreciable change in the thermal stability of PA12 in the presence of small amount of rubber phase. A good correlation was observed between the thermal properties and phase morphology of the blends. Melting and crystallisation behaviours of the blends were analysed by differential scanning calorimetry (DSC). These results showed that the melting and crystallisation behaviours of PA12 were not significantly affected by blending with rubbers. It was also observed that the functional group present in the rubber phase has little effect on the melting and crystallisation behaviours of PA12.     

Influence of microstructure and flexibility of maleated styrene-b-(ethylene-co-butylene)-b-styrene rubber on the mechanical properties of polyamide 12

The present investigation deals with the mechanical and morphological properties of binary polyamide 12/maleic anhydride-grafted styrene-b-(ethylene-co-butylene)-b-styrene rubber (PA12/SEBS-g-MA) blends at varying dispersed phase (SEBS-g-MA) concentrations. Tensile behavior, impact strength and crystallinity of these blend systems were evaluated. Influence of microstructure, dispersed phase particle size, and ligament thickness on the impact toughness of the blend was studied. DSC data indicated an increase in crystallinity of PA12 in the blends. Tensile modulus and strength decreased while impact strength and elongation-at-break increased with the elastomer concentration. The enhanced properties were supported by interphase adhesion between the grafted maleic groups of rubber with polar moiety of polyamide 12. Analysis of the tensile data employing simple theoretical models showed the variation of stress concentration effect with blend composition.     

Toughness improvement of novel biobased aromatic polyamide/SEBS/organoclay ternary hybrids

Biobased aromatic polyamide/organoclay (Cloisite30B, C30B) nanocomposites were melt-compounded with reactive and nonreactive styrene–ethylene–butylene–styrene (SEBS) rubbers at different weight contents to form ternary and quaternary blends. The mechanical properties were investigated as a function of the blend composition. The elongation at break and the impact strength increase with increasing SEBS rubber content, whereas the Young's modulus logically decreases proportionally to SEBS amount. Extra addition of SEBS grafted maleic anhydride (SEBS-g-MA) induces a synergistic effect. The SEBS-g-MA makes it possible to limit the aforementioned rigidity loss and to greatly increase the impact strength. The critical strain energy release rate increases significantly when both reactive and nonreactive rubbers are combined. Three types of microstructures appear depending on the blend composition: (1) small and numerous well-dispersed particles when reactive rubber is used, (2) about 10 times bigger and less numerous well-dispersed particles in the case of nonreactive rubber, and (3) a flocculated dispersion of small particles when both reactive and nonreactive rubber are added. Finally, the polyamide performances were significantly increased when the flocculated morphology was noticed due to a better PAXD/SEBS interfacial adhesion given by the SEBS-g-MA compatibilization and to a thinner rubber distribution in the matrix. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48888.     

Wide-angle X-ray diffraction investigation on crystallization behavior of PA6/PS/SEBS-g-MA blends

Blends of polystyrene/polyamide 6 (PS/PA6) compatibilized by styrene-ethylene/butylene-styrene (SEBS) elastomer grafted with maleic anhydride were prepared by melt blending. Wide-angle X-ray diffraction (WAXD) scans indicated a skin–core structure formed in the specimens during the injection-molding process. The results showed that the specimens tended to form the α-crystalline form in the core region, but the γ-crystalline form in the skin region. The influences of PS and SEBS-g-MA on the crystallization of PA6 were different in the core region and skin region. In the core region, PS made the PA6 tend to be in the γ-crystalline form, but the influence of PS was contrary in the skin region. SEBS-g-MA had both enhancement and toughening effects on the blends. The mechanical properties of the blends were determined by the combined action of the two aforementioned factors.     

Compatibilization of polyethylene terephthalate/polypropylene blends with styrene–ethylene/butylene–styrene (SEBS) block copolymers

Blends of polyethylene terephthalate (PET) and polypropylene (PP) at compositions 20/80 and 80/20 were modified with three different styrene–ethylene/butyl–ene-styrene (SEBS) triblock copolymers with the aim of improving the compatibility and in particular the toughness of the blends. The compatibilizers involved an unfunctionalized SEBS and two functionalized grades containing either maleic anhydride (SEBS-g-MAH) or glycidyl methacrylate (SEBS-g-GMA) grafted to the midblock. The effects of the compatibilizers were evaluated by studies on morphology and mechanical, thermal and rheological properties of the blends. The additon of 5 wt % of a SEBS copolymer was found to stabilize the blend morphology and to improve the impact strength. The effect was, however, far more pronounced with the functionalized copolymers. Particularly high toughness combined with rather high stiffness was achieved with SEBS-g-GMA for the PET-rich composition. Addition of the functionalized SEBS copolymers resulted in a finer dispersion of the minor phase and clearly improved interfacial adhesion. Shifts in the glass transition temperature of the PET phase and increase in the melt viscosity of the compatibilized blends indicated enhanced interactions between the discrete PET and PP phases induced by the functionalized compatibilizer, in particular SEBS-g-GMA. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:241–249, 1997     

Influence of thermoplastic elastomers on mechanical properties and morphologies of isotactic polypropene/glass bead hybrid composites

Glass bead-reinforced isotactic polypropene hybrid composites containing 0–20 vol % thermoplastic elastomers were prepared to study both structure/property relationship and morphology development. Polystyrene-block-poly(ethene-co-but-1-ene)-block-polystyrene (SEBS) and the corresponding block copolymer grafted with maleic anhydride (SEBS-g-MA) were used as thermoplastic elastomers. Hybrid composites containing SEBS gave higher Young's moduli than did those containing SEBS-g-MA. The experimental Young's moduli were in good agreement with the theoretical predictions according to Lewis and Nielsen. The lower moduli of hybrid composites containing SEBS-g-MA were attributed to interlayer formation and in situ encapsulation of glass beads, resulting in core–shell particles. This elastomeric interlayer impaired the filler reinforcement. Analysis of tensile yield stress and results of lap-shear tests confirmed strong filler–polymer interactions in composites containing SEBS-g-MA. Only in excess of a critical volume fraction did SEBS-g-MA afford a significant improvement of the notched Izod impact strength. In contrast to stiffness, Izod impact strength was not influenced by the type of elastomer and morphology. Investigation of crystallization and scanning electron microscopic studies proved the in situ encapsulation of the glass beads with SEBS-g-MA, whereas SEBS addition results in separately dispersed glass beads and SEBS microphases. © 1996 John Wiley & Sons, Inc.     

Structure–property relationships in ternary polymer blends with core–shell inclusions: revisiting the critical role of the viscosity ratio

Structure–property relationship in typical polypropylene/polycarbonate/poly[styrene-b-(ethylene-co-butylene)-b-styrene] (PP/PC/SEBS) ternary blends containing maleated SEBS (SEBS-g-MAH) was investigated. Three grades of PC with different melt viscosities were used, and changes in blend morphology from PC/SEBS core–shell particles partially surrounded by SEBS-g-MAH to inverse SEBS/PC core–shell particles in PP matrix were observed upon varying the viscosity ratio of PC to SEBS. It was found that the viscosity ratio completely controls the size of the core–shell droplets and governs the type, population, and shape of the dispersed domains, as evidenced by rheological, mechanical, and thermomechanical behavioral assessments. Dynamic mechanical analysis of samples with common (PC–SEBS) and inverse (SEBS–PC) core–shell particles revealed that they show completely different behaviors: blends containing PC–SEBS presented a higher storage and loss modulus, while blends containing SEBS–PC exhibited a lower β-transition temperature. Moreover, ternary blends with PC cores showed the highest Young’s modulus values and the lowest impact strength, due to the different fracture modes of the blends containing PC–SEBS and SEPS–PC core–shell droplets, which present debonding and shell-fracture mechanisms, respectively. Morphological observations of blends with high-molecular-weight PC demonstrated the presence of detached droplets and rods of PC in the PP matrix, along with composite core–shell and rod-like particles. Micrographs of the fracture surfaces confirmed the proposed mechanisms, given the presence of stretched (debonded) PC (SEBS) cores encapsulated by SEBS (PC), which require more (less) energy to achieve fracture. The correlation between the mechanical and morphological properties proves that decreasing core diameter and shell thickness has positive effects on the impact strength but decreases the Young’s modulus.     

Comparison of the toughening behavior of nylon 6 versus an amorphous polyamide using various maleated elastomers

The toughening effect of two types of elastomers based on ethylene/α-olefin copolymers, viz, an ethylene/propylene copolymer (EPR) with its maleated version, EPR-g-MA, and an ethylene/1-octene copolymer (EOR) with its maleated versions, EOR-g-MA-X% (X=0.35, 1.6, 2.5), for two classes of polyamides: semi-crystalline nylon 6 versus an amorphous polyamide (Zytel 330 from DuPont), designated as a-PA, was explored. The results are compared with those reported earlier based on a styrenic triblock copolymer having a hydrogenated midblock, SEBS, and its maleated version, SEBS-g-MA, elastomer system. Izod impact strength was examined as a function of rubber content, rubber particle size and temperature. All three factors influence the impact behavior considerably for the two polyamide matrices. The a-PA is found to require a somewhat lower content of rubber for toughening than nylon 6. Very similar optimum ranges of rubber particle sizes were observed for ternary blends of EOR-g-MA/EOR with each of the two polyamides while blends based on mixtures of EPR-g-MA/EPR and SEBS-g-MA/SEBS (where the total rubber content is 20% by weight) show only an upper limit for a-PA but an optimum range of particle sizes for nylon 6 for effective toughening. Higher EPR-g-MA contents lead to lower ductile-brittle transition temperatures (T_db) as expected; however, a-PA binary blends with EPR-g-MA have a much lower T_db than do nylon 6 blends when the content of the maleated elastomer is not high. A minimum in plots of ductile-brittle transition temperature versus particle size appears for ternary blends of each of the matrices with EOR-g-MA/EOR; blends based on SEBS-g-MA/SEBS, in most cases, show higher ductile-brittle transition temperatures, regardless of the matrix. However, blends with EPR-g-MA/EPR show comparable T_db with those based on EOR-g-MA/EOR for the amorphous polyamide but show the lowest ductile-brittle transition temperatures for nylon 6 within the range of particle sizes examined. For the blends with a bimodal size distribution, the global weight average rubber particle size is inappropriate for correlating the Izod impact strength and ductile-brittle transition temperature. In general, trends for this amorphous polyamide are rather similar to those of semi-crystalline nylon 6.     

Reactively compatibilised polyamide6/ethylene-co-vinyl acetate blends: mechanical properties and morphology

Mechanical properties and morphological studies of compatibilised blends of PA6/EVA-g-MA and PA6/EVA/EVA-g-MA were studied as functions of maleic anhydride content (MA) and dispersed phase (EVA-g-MA) concentrations, respectively at blending composition of 20 wt% dispersed phase (EVA-g-MA or combination of EVA and EVA-g-MA). The maleic anhydride (MA) was varied from 1 to 6 wt% in the PA6/EVA-g-MA blend, whereas MA concentration was fixed at 2 wt% in the ternary compositions with varying level of EVA-g-MA. ATR-IR spectroscopy revealed the formation of in situ copolymer during reactive compatibilisation of PA6 and EVA-g-MA. It was found that notched Izod impact strength of PA6/EVA-g-MA blends increased significantly with MA content in EVA-g-MA. The brittle to tough transition temperature of reactively compatibilised blends was found to be at 23 °C. The impact fractured surface topology reveals extensive deformation in presence of EVA-g-MA whereas; uncompatibilised PA6/EVA blend shows dislodging of EVA domains from the matrix. Tensile strength of the PA6/EVA-g-MA blends increased significantly as compared to PA6/EVA blends. Analysis of the tensile data using predictive theories showed an enhanced interaction of the dispersed phase and the matrix. It is observed from the phase morphological analysis that the average domain size of the PA6/EVA-g-MA blends is found to decrease gradually with increase in MA content of EVA-g-MA. A similar decrease is also found to observe in PA6/EVA/EVA-g-MA blends with increase in EVA-g-MA content, which suggest the coalescence process is slower in presence of EVA-g-MA. An attempt has been made to correlate between impact strength and morphological parameters with regard to the compatibilised system over the uncompatibilised system.     

Compatibilisation of blends of poly(vinyl chloride) and poly(styrene-block-(ethylene-co-butadiene)-block–styrene) with maleic anhydride grafting

Abstract

The mechanical properties of blends of poly (vinyl chloride) (PVC) and poly (styrene-block-(ethylene-co-butadiene)-block–styrene) (SEBS) were investigated using maleic anhydride grafted SEBS (SEBS-g-MAH) as a compatibiliser. The results indicated that addition of a small amount of SEBS-g-MAH during melt blending significantly improved the mechanical properties of PVC/SEBS blends. The impact strength of the compatibilised PVC/SEBS blends was found to reach a maximum of 53·5±2·78 KJ m^?2 at room temperature and a maximum of 32·8±1·66 KJ m^?2 at ?20°C at an SEBS-g-MAH loading level of 6 phr. The two glass transition temperatures of the components in the blends converged to some degree upon addition of SEBS-g-MAH for compatibilisation. At room temperature the dynamic storage modulus of the compatibilised blends was higher than that of the blends without compatibilisation. The size of the dispersed phase domains in the blends was appreciably reduced on addition of SEBS-g-MAH during melt blending according to scanning electron microscopy. All the above observations revealed that SEBS-g-MAH enhanced the compatibility between PVC and SEBS in the PVC/SEBS blends.     

Effects of electron beam irradiation on the structure–property behavior of blends based on low density polyethylene and styrene-ethylene-butylene-styrene-block copolymers

Low density polyethylene (LDPE) blends with different additives were exposed to various doses of electron beam irradiation. The additives used were styrene-ethylene-butylene-styrene-block copolymers (SEBS), styrene-ethylene-butylene-styrene-block copolymer grafted with maleic anhydride (SEBS-g-MA) and mineral compounds. The structure–property behavior of electron beam irradiated blends was characterized in terms of mechanical, thermal, and electrical resistivity properties. The results indicated that the unirradiated LDPE blends with the different compositions showed improved mechanical properties, thermal and volume resistivity properties than pure LDPE. However, the improvement in properties of unirradiated blends by using SEBS-g-MA was higher than using SEBS copolymer. Further improvement in the mechanical, thermal and electrical properties of the LDPE blends was achieved after electron beam irradiation. The limited oxygen index (LOI) data revealed that the LDPE/SEBS-g-MA/ATH blend was changed from combustible to self-extinguishing material after electron beam irradiation to a dose of 100 kGy. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

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     

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     

A study on the effects of SEBS‐g‐MAH on the phase morphology and mechanical properties of polypropylene/polycarbonate/SEBS ternary polymer blends

In this work, five ternary blends based on 70% by weight (wt %) of polypropylene (PP) with 30% wt of polycarbonate (PC)/poly(styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene)(SEBS) dispersed phase consists of 15 wt % PC and 15 wt % reactive (maleic anhydride grafted) and nonreactive SEBS mixtures at various ratios were prepared in a co‐rotating twin screw extruder. scanning electron microscopy (SEM) micrographs showed that the blends containing only nonreactive SEBS exhibited a fine dispersion of core‐shell particles. With decreasing the SEBS/SEBS‐g‐Maleic Anhydride (MAH) weight ratio, the morphology changed from the core‐shell particles to a mixed of core‐shell, rod‐like and individual particles. This variation in phase morphology affected the thermal and mechanical properties of the blends. DSC results showed that the blends containing only nonreactive SEBS exhibited a minimum in degree of crystallinity due to the homogeneous nucleation of core‐shell particles. Mechanical testing showed that in the SEBS/SEBS‐g‐MAH weight ratio of 50/50, the modulus and impact strength increased compared with the PP matrix while the yield stress had minimum difference with that of PP matrix. These effects could be attributed to the formation of those especial microstructures revealed by the SEM studies. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effect of Thermoplastic Elastomer on Melt Rheological and Fracture Behavior of Poly(Lactic Acid)

Poly(lactic acid) (PLA) was melt blended with thermoplastic elastomer, maleic anhydride grafted poly[styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS-g-MA) copolymer with varied concentration (10–40?wt%) using twin screw extruder. Dynamic rheological behavior of PLA/SEBS-g-MA blends investigated a transition from liquid-like behavior to solid-like behavior in the composition range of 10–20?wt% of SEBS-g-MA. The capillary rheometer analysis showed enhanced shear viscosity with increase in SEBS-g-MA content. At 10?wt% of SEBS-g-MA, a maximum in the non-essential work of fracture was observed which reflects resistance to crack propagation. Scanning electron microscopy revealed a transition in deformation mechanisms from voids, to fibrillation and cavitation.     

Morphology and Mechanical Properties of iPP/Silica Composites Modified with (Styrene-b-ethylene-co-butylene-b-styrene) Grafted with Maleic Anhydride

The effects of different silica grades and elastomer content on interfacial properties, morphology and mechanical properties of polypropylene/silica 96/4 composites modified with added 5, 10, 15, and 20% of poly(styrene-b-ethylene-co-butylene-b-styrene) grafted with maleic anhydride (SEBS-g-MA) were investigated. The iPP/silica/SEBS-g-MA composites were designed by adding four silica fillers differing in size (nano- vs. micro-) and in surface properties (hydrophilic vs. hydrophobic) and SEBS-g-MA that was used as a proven effective impact modifier and compatibilizer simultaneously. The morphology of every composite was a spectrum of several morphologies rather than one exclusive morphology. Good concordance between observed and predicted morphology indicated that the morphology of a particular composite was controlled primarily by interfacial properties. Tensile and impact properties were influenced primarily by competitive effects of a stiff filler and tough SEBS-g-MA elastomer. Increased impact strength and strain at break caused by adding SEBS-g-MA indicated a significant overcoming of the elastomeric toughening effect in relation to the filler’s stiffening effect.