Recycled poly(ethylene terephthalate)/linear low‐density polyethylene blends through physical processing

Poly(styrene‐ethylene/butylene‐styrene) (SEBS) was used as a compatibilizer to improve the thermal and mechanical properties of recycled poly(ethylene terephthalate)/linear low‐density polyethylene (R‐PET/LLDPE) blends. The blends compatibilized with 0–20 wt % SEBS were prepared by low‐temperature solid‐state extrusion. The effect of SEBS content was investigated using scanning electron microscope, differential scanning calorimeter, dynamic mechanical analysis (DMA), and mechanical property testing. Morphology observation showed that the addition of 10 wt % SEBS led to the deformation of dispersed phase from spherical to fibrous structure, and microfibrils were formed at the interface between two phases in the compatibilized blends. Both differential scanning calorimeter and DMA results revealed that the blend with 20 wt % SEBS showed better compatibility between PET and LLDPE than other blends studied. The addition of 20 wt % of SEBS obviously improved the crystallizibility of PET as well as the modulus of the blends. DMA analysis also showed that the interaction between SEBS and two other components enhanced at high temperature above 130°C. The impact strength of the blend with 20 wt % SEBS increased of 93.2% with respect to the blend without SEBS, accompanied by only a 28.7% tensile strength decrease. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

SBS and SEBS block copolymers as impact modifiers for polypropylene compounds

Blends of polypropylene (PP) and thermoplastic elastomers (TPE), namely SBS (styrene‐butadiene‐styrene) and SEBS (styrene‐ethylene/1‐butene‐styrene) block copolymers, were prepared to evaluate the effectiveness of the TPE type as an impact modifier for PP and influence of the concentration of elastomer on the polymer properties. Polypropylene homopolymer (PP‐H) and ethylene–propylene random copolymer (PP‐R) were evaluated as the PP matrix. Results showed that TPEs had a nucleating effect that caused the PP crystallization temperature to increase, with SBS being more effective than SEBS. Microstructure characterization tests showed that in most cases PP/SEBS blends showed the smallest rubber droplets regardless of the matrix used. It was seen that SEBS is a more effective toughening agent for PP than SBS. At 0°C the Izod impact strength of the PP‐H/SEBS 30% b/w blend was twofold higher than the SBS strength, with the PP‐R/SEBS 30% b/w blend showing no break. A similar behavior on tensile properties and flexural modulus were observed in both PP/TPE blends. Yield stress and tensile strength decreased and elongation at break increased by expanding the dispersed elastomeric phase in the PP matrix. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 254–263, 2005     

Analytical interpretations of static and dynamic mechanical properties of thermoplastic elastomer toughened PLA blends

Poly(lactic acid) (PLA) was melt blended with thermoplastic elastomer (TPE) styrene–ethylene–butylene–styrene‐g‐maleic anhydride (SEBS‐g‐MA) copolymer using a micro compounder which used melt recirculation approach for efficient dispersion of SEBS‐g‐MA in PLA. The SEBS‐g‐MA volume fraction (Φ_d) was varied between 0.07 and 0.48. Dynamic mechanical analysis showed 10.4 °C decrease in glass transition temperature at Φ_d = 0.48. Differential scanning calorimetry results exhibited shift in cold crystallization temperature to a higher temperature in the presence of SEBS‐g‐MA. Thermogravimetric analysis presented enhanced thermal stability of PLA/SEBS‐g‐MA blends. Tensile strength and modulus decreased while elongation‐at‐break and Izod impact strength increased in the blends. Theoretical models were employed to analyze the tensile properties of the blends in order to evaluate the blend structure. The microstructural attributes were characterized by wide‐angle X‐ray diffraction, Fourier‐transform infrared spectroscopy, and scanning electron microscopy of cryofractured, impact fractured, and tensile fractured surfaces. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45644.     

Interface modification of compatibilized polyethylene terephthalate/polypropylene blends: Effect of compatibilization on thermomechanical properties and thermal stability

Polyethylene terephthalate (PET) and polypropylene (PP) are incompatible thermoplastics because of differences in chemical structure and polarity, hence their blends possess inferior mechanical and thermal properties. Compatibilization with a suitable block/graft copolymer is one way to improve the mechanical and thermal properties of the PET/PP blend. In this study, the toughness, dynamic mechanical analysis (DMA), and thermogravimetric analysis (TGA) of PET/PP blends were investigated as a function of different content of styrene‐ethylene‐butylene‐styrene‐g‐maleic anhydride (SEBS‐g‐MAH) compatibilizer. PET, PP, and SEBS‐g‐MAH were melt‐blended in a single step using the counter rotating twin screw extruder with compatibilizer concentrations of 0, 5, 10, and 15 phr, respectively. The impact strength of compatibilized blend with 10 phr SEBS‐g‐MAH increased by 300% compared to the uncompatibilized blend. Scanning electron microscope (SEM) micrographs show that the addition of 10 phr SEBS‐g‐MAH compatibilizer into the PET/PP blends decreased the particle size of the dispersed PP phase to the minimum level. The improvement of the storage modulus and the decrease in the glass transition temperature of the PET phase indicated an interaction among the blend components. Thermal stability of the PET/PP blends was significantly improved because of the addition of SEBS‐g‐MAH. J. VINYL ADDIT. TECHNOL., 23:45–54, 2017. © 2015 Society of Plastics Engineers     

Blends of SBS triblock copolymer with poly(2,6‐dimethyl‐1,4‐phenylene oxide)/polystyrene mixture

Blends of styrene–butadiene–styrene (SBS) or styrene–ethylene/1‐butene–styrene (SEBS) triblock copolymers with a commercial mixture of polystyrene (PS) and poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PPO) were prepared in the melt at different temperatures according to the chemical kind of the copolymer. Although solution‐cast SBS/PPO and SBS/PS blends were already known in the literature, a general and systematic study of the miscibility of the PS/PPO blend with a styrene‐based triblock copolymer in the melt was still missing. The thermal and mechanical behavior of SBS/(PPO/PS) blends was investigated by means of DSC and dynamic thermomechanical analysis (DMTA). The results were then compared to analogous SEBS/(PPO/PS) blends, for which the presence of a saturated olefinic block allowed processing at higher temperatures (220°C instead of 180°C). All the blends were further characterized by SEM and TGA to tentatively relate the observed properties with the blends' morphology and degradation temperature. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2698–2705, 2003     

Morphology and mechanical properties of styrene–ethylene/butylene–styrene triblock copolymer/high‐density polyethylene composites

The morphology and mechanical properties of a styrene–ethylene/butylene–styrene triblock copolymer (SEBS) incorporated with high‐density polyethylene (HDPE) particles were investigated. The impact strength and tensile strength of the SEBS matrix obviously increased after the incorporation of the HDPE particles. The microstructure of the SEBS/HDPE blends was observed with scanning electron microscopy and polar optical microscopy, which illustrated that the SEBS/HDPE blends were phase‐separation systems. Dynamic mechanical thermal analysis was also employed to characterize the interaction between SEBS and HDPE. The relationship between the morphology and mechanical properties of the SEBS/HDPE blends was discussed, and the toughening mechanism of rigid organic particles was employed to explain the improvement in the mechanical properties of the SEBS/HDPE blends. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

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     

Reactive mixing of PET and PET/PP blends with glycidyl methacrylate–modified styrene‐b‐(ethylene‐co‐olefin) block copolymers

Styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene (SEBS) and styrene‐b‐(ethylene‐co‐propylene) (SEP, SEPSEP) block copolymers with different styrene contents and different numbers of blocks in the copolymer chain were functionalized by melt radical grafting with glycidyl methacrylate (GMA) and employed as compatibilizers for PET‐based blends. Binary blends of PET with both functionalized (SEBS‐g‐GMA, SEP‐g‐GMA, SEPSEP‐g‐GMA) and neat (SEBS, SEP, SEPSEP) copolymers (75 : 25 w/w) and ternary blends of PET and PP (75 : 25 w/w) with various amounts (2.5–10 phr) of both modified and unmodified copolymers were prepared in an internal mixer, and their properties were evaluated by SEM, DSC, melt viscosimetry, and tensile and impact tests. The roles of the chemical structure, grafting degree, and concentration of the various copolymers on blend compatibilization was investigated. The blends with the grafted copolymers showed a neat improvement of phase dispersion and interfacial adhesion compared to the blends with nonfunctionalized copolymers. The addition of grafted copolymers resulted in a marked increase in melt viscosity, which was accounted for by the occurrence of chemical reactions between the epoxide groups of GMA and the carboxyl/hydroxyl end groups of PET during melt mixing. Blends with SEPSEP‐g‐GMA and SEBS‐g‐GMA, at concentrations of 5–10 phr, showed a higher compatibilizing effect with enhanced elongation at break and impact resistance. The effectiveness of GMA‐functionalized SEBS was then compared to that of maleic anhydride–grafted SEBS. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2201–2211, 2005     

Evaluation of mechanical properties of polypropylene/polycarbonate/SEBS ternary polymer blends using Taguchi experimental analysis

In this work, ternary polymer blends based on polypropylene (PP)/polycarbonate (PC)/poly(styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene) (SEBS) triblock copolymer and a reactive maleic anhydride grafted SEBS (SEBS‐g‐MAH) at fixed compositions are prepared using twin‐screw extruder at different levels of die temperature (235‐245‐255°C), screw speed (70‐100‐130 rpm), and blending sequence (M1‐M2‐M3). In M₁ procedure, all of the components are dry blended and extruded simultaneously using Brabender twin‐screw extruder, whereas in M₂ procedure, PC, SEBS, and SEBS‐g‐MAH minor phases are first preblended in twin‐screw extruder and after granulating are added to PP continuous phase in twin‐screw extruder. Consequently, in M₃ procedure, PP and SEBS‐g‐MAH are first preblended and then are extruded with other components. The influence of these parameters as processing conditions on mechanical properties of PP/PC/SEBS ternary blends is investigated using L9 Taguchi experimental design. The responding variables are impact strength and tensile properties (Young's modulus and yield stress), which are influenced by the morphology of ternary blend, and the results are used to perform the analysis of mean effect as well. It is shown that the resulted morphology, tensile properties, and impact strength are influenced by extrusion variables. Additionally, the optimum processing conditions of ternary PP/PC/SEBS blends were achieved via Taguchi analysis. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Toughening of polypropylene with styrene/ethylene‐butylene/styrene tri‐block copolymer: Effects of mixing condition and elastomer content

The effect of processing conditions and elastomer content on the toughening of Polypropylene (PP) by melt blending with styrene/ethylene‐butylene/styrene tri‐block copolymer (SEBS) in a twin‐screw extruder has been investigated. The parameters analyzed were: temperature profile, screw speed, and feed rate of the blend components. Their effect was evaluated through the mechanical properties (tensile strength and Izod impact resistance at room temperature) as well as the morphology of the dispersed phase by means of scanning electron microscopy (SEM). The results showed that the impact resistance increases with increasing rotor speed and feed rate and decreases when the temperature profile is increased. The parameter with the greatest effect on the mechanical properties was the variation in rotor speed. Despite the fact that impact resistance as high as 25 times that of neat PP has been achieved with blends containing 20 wt % SEBS, no significant modification in phase morphology has been observed. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2185–2193, 2001     

Compatibilization effects of styrenic/rubber block copolymers in polypropylene/polystyrene blends

Compatibilizing effects of styrene/rubber block copolymers poly(styrene‐b‐butadiene‐b‐styrene) (SBS), poly(styrene‐b‐ethylene‐co‐propylene) (SEP), and two types of poly(styrene‐b‐ethylene‐co‐butylene‐b‐styrene) (SEBS), which differ in their molecular weights on morphology and selected mechanical properties of immiscible polypropylene/polystyrene (PP/PS) 70/30 blend were investigated. Three different concentrations of styrene/rubber block copolymers were used (2.5, 5, and 10 wt %). Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to examine the phase morphology of blends. The SEM analysis revealed that the size of the dispersed particles decreases as the content of the compatibilizer increases. Reduction of the dispersed particles sizes of blends compatibilized with SEP, SBS, and low‐molecular weight SEBS agrees well with the theoretical predictions based on interaction energy densities determined by the binary interaction model of Paul and Barlow. The SEM analysis confirmed improved interfacial adhesion between matrix and dispersed phase. The TEM micrographs showed that SBS, SEP, and low‐molecular weight SEBS enveloped and joined pure PS particles into complex dispersed aggregates. Bimodal particle size distribution was observed in the case of SEP and low‐molecular weight SEBS addition. Notched impact strength (a_k), elongation at yield (ε_y), and Young's modulus (E) were measured as a function of weight percent of different types of styrene/rubber block copolymers. The a_k and ε_y were improved whereas E gradually decreased with increasing amount of the compatibilizer. The a_k was improved significantly by the addition of SEP. It was found that the compatibilizing efficiency of block copolymer used is strongly dependent on the chemical structure of rubber block, molecular weight of block copolymer molecule, and its concentration. The SEP diblock copolymer proved to be a superior compatibilizer over SBS and SEBS triblock copolymers. Low‐molecular weight SEBS appeared to be a more efficient compatibilizer in PP/PS blend than high‐molecular weight SEBS. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 291–307, 1999     

Modification of tensile and impact properties of poly(butylene terephthlate) by incorporation of styrene‐ethylene‐butylene‐styrene and maleic anhydride‐grafted‐SEBS (SEBS‐g‐MA) terpolymer

Tensile behavior and impact strength of poly(butylene terephthlate) (PBT)/styrene‐ethylene‐butylene‐styrene (SEBS) copolymer blends were studied at SEBS volume fraction 0–0.38. Tensile modulus and strength decreased, whereas breaking elongation increased with SEBS content. Predictive models are used to evaluate the tensile properties. Strength properties were dependent on the crystallinity of PBT and phase adhesion. The normalized notched Izod impact strength increased with the SEBS content; at Φ_d = 0.38, the impact strength enhanced to five times that of PBT. Scanning electron microscopy was used to examine phase morphology. Concentration and interparticle distance of the dispersed phase influenced impact toughening. In the presence of maleic anhydride‐grafted SEBS (SEBS‐g‐MAH), the tensile modulus and strength decreased significantly, while normalized relative notched Izod impact strength enhanced to 7.5 times because of enhanced interphase adhesion. POLYM. ENG. SCI., 53:2242–2253, 2013. © 2013 Society of Plastics Engineers     

Morphology and mechanical properties of polyamide 12 blends with styrene/ethylene–butylene/styrene rubbers with and without maleation

Blends of polyamide 12 (PA12) with styrene/ethylene–butylene/styrene (SEBS) and maleic anhydride grafted SEBS (SEBS‐g‐MA) were prepared by twin‐screw extrusion and injection molding. The morphology, mechanical properties, and dynamic mechanical properties of the blends were studied. The morphology of the blends was evaluated from the etched surfaces of cryogenically fractured specimens with scanning electron microscopy. The morphological parameters showed that the PA12/SEBS‐g‐MA blends (PM series) exhibited a finer and more uniform rubber dispersion than the PA12/SEBS blends (PS series) because of the interfacial chemical reactions. SEBS functionalization via maleic anhydride grafting strongly affected the morphological parameters, such as the domain size, interfacial area per unit of volume, and critical interparticle distance, but the distribution of the rubber domains in the blends was less affected. Tensile and impact studies showed that the PS blends had worse mechanical properties than the PM blends. The tensile strength and elongation at break of the PM blends were considerably greater than those of the PS blends. The fracture toughness and energy values determined for notched Charpy specimens in high‐speed impact tests were markedly higher for the PM blends than for the PS blends. A similar observation was obtained from instrumented falling weight impact studies. Dynamic mechanical analysis confirmed the incompatibility of the blend components because the glass‐transition temperatures of PA12 and the rubber phase (SEBS and SEBS‐g‐MA) were not affected. © 2005 Wiley Periodicals, Inc. J Appl polym Sci 95: 1376–1387, 2005     

Toughening and compatibilization of polyphenylene sulfide/nylon 66 blends with SEBS and maleic anhydride grafted SEBS triblock copolymers

In this study, styrene‐b‐ethylene/butylene‐b‐styrene triblock copolymer (SEBS) and maleic anhydride grafted SEBS (SEBS‐g‐MA) were used as compatibilizers for the blends of polyphenylene sulfide/nylon 66 (PPS/PA66). The mechanical properties, including impact and tensile properties and morphology of the blends, were investigated by mechanical properties measurements and scanning electron microscopy. Impact measurements indicated that the impact strength of the blends increases slowly with elastomer (SEBS and SEBS‐g‐MA) content upto 20 wt %; thereafter, it increases sharply with increasing elastomer content. The impact energy of the elastomer‐compatibilized PPS/PA66 blends exceeded that of pure nylon 66, implying that the nylon 66 can be further toughened by the incorporation of brittle PPS minor phase in the presence of SEBS or SEBS‐g‐MA. The compatibilization efficiency of SEBS‐g‐MA for nylon‐rich PPS/PA66 was found to be higher than SEBS due to the in situ forming SEBS interphase between PPS and nylon 66. The correlation between the impact property and morphology of the SEBS‐g‐MA compatibilized PPS/PA66 blends is discussed. The excellent impact strength of the nylon‐rich blends resulted from shield yielding of the matrix. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Tough polyamide 6/core–shell blends prepared via in situ anionic polymerization of ε‐caprolactam by reactive extrusion

In this study, the molten ε‐caprolactam (CL) solution of maleated styrene‐ethylene/butylene‐styrene block copolymer (SEBS‐g‐MA) and polystyrene (PS) containing catalyst and activator were introduced into a twin screw extruder, and polyamide 6 (PA6)/SEBS/PS blends were successfully prepared via anionic polymerization of CL by reactive extrusion. The mechanical properties measurements indicated that both the elongation at break and notched Izod impact strength of PA6/SEBS/PS (85/10/5) blends were improved distinctly with slight loss of tensile and flexural strength as compared to that of pure PA6. The images of transmission electron microscopy showed that a core–shell structure with PS core and poly (ethene‐co‐1‐butene) (PEB) shell was formed within the PA6 matrix. Fourier transform infrared was used to investigate the formation mechanisms of the core–shell structure. POLYM. ENG. SCI., 53:2705–2710, 2013. © 2013 Society of Plastics Engineers     

Mechanical,thermal, and microstructural properties of polypropylene/polyamide‐6/styrene‐ethylene‐butadiene‐styrene polymer alloys

Interfacial agents as compatibilizers have recently been introduced into polymer blends to improve the microstructure and mechanical properties of thermoplastics. In this way, it is possible to prepare a mixture of polymeric materials that can have superior mechanical properties over a wide temperature range. In this study, an incompatible blend of polypropylene (PP) and polyamide‐6 (PA₆) were made compatible by the addition of 10% styrene–ethylene–butadiene–styrene copolymer (SEBS). The mixing operation was conducted by using a twin‐screw extruder. The morphology and the compatibility of the mixtures were examined by SEM and DSC techniques. Furthermore, the elastic modulus, tensile and yield strengths, percentage elongation, hardness, melt flow index, Izod impact resistance, heat deflection temperature (HDT), and Vicat softening point values of polymer alloys of various ratios were determined. It was found that the addition of SEBS to the structures decreased the tensile strength, yield strength, elastic modulus, and hardness, whereas it increased the Izod impact strength and percentage elongation values. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3485–3491, 2003     

Preparation and properties of PC/SAN alloy modified with styrene‐ethylene‐butylene‐styrene block copolymer

A polycarbonate (PC)/ poly (styrene‐co‐acrylonitrile) (SAN) alloy modified with styrene‐ethylene‐butylene‐styrene (SEBS) block copolymer was prepared and the influence of SEBS content, PC content, and types of modifier on Izod notched impact strength, tensile strength, flexural strength, and Vicat softening temperature was studied. The results showed that the addition of SEBS could obviously increase the Izod notched impact strength and the elongation at break and decrease the tensile and flexural strength and Vicat softening temperature. PC/SAN alloy modified with SEBS had better mechanical properties than the PC/SAN alloy modified with ABS. DSC analysis and SEM photographs revealed that the SEBS was not only distributed in the SAN phase but also distributed in PC phase in a PC/SAN/SEBS alloy while the ABS was mainly distributed in SAN phase in a PC/SAN/ABS alloy. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Effect of polypropylene on the rheology of co‐continuous PS/SEBS blends

Polypropylene (PP) was added to a co‐continuous blend of polystyrene (PS) and styrene‐ethylene/butylene‐styrene (SEBS) to investigate the effect of PP on the morphology and rheological behavior of PS/SEBS blends. For this purpose, a reference blend of 50 wt% PS and 50 wt% SEBS was chosen and an isotactic PP was added to it by increments of 10 wt% up to a maximum of 50 wt% of the total weight. Environmental SEM (ESEM) studies on the PS/SEBS/PP blends showed that PP could be added up to 10 wt% without changing the morphology of the co‐continuous PS/SEBS blend, whereas at 20 wt% PP formed a separate discrete phase. The discrete PP phase finally formed a fully developed matrix structure from 40 wt% onwards. Dynamic rheological measurements showed that at low frequencies the storage modulus was largely unaffected by addition of PP in small concentrations (up to 10 wt%), showing a significant effect of the PP/SEBS interface at low deformation rates. Melt strength tests on the PS/SEBS/PP blends showed the existence of a proportional correlation with their corresponding storage moduli, measured at frequencies from 10–100 rad/s. POLYM. ENG. SCI., 45:1432–1444, 2005. © 2005 Society of Plastics Engineers     

Study on morphology and viscoelastic properties of PP/PET/SEBS ternary blend and their fibers

The morphology development of polypropylene (PP)/polyethylene terephthalate (PET)/styrene‐ethylene‐butylene‐styrene (SEBS) ternary blends and their fibers were studied by means of scanning electron microscopy (SEM) in conjunction with the melt linear viscoelastic measurements. The morphology of the blends was also predicted by using Harkin's spreading coefficient approach. The samples varying in composition with PP as the major phase and PET and SEBS as the minor phases were considered. Although SEM of the binary blends showed matrix‐dispersed type morphology, the ternary blend samples exhibited a morphological feature in which the dispersed phase formed aggregates consisting of both PET and SEBS particles distributed in the PP matrix. The SEM of the blend samples containing 30 and 40 wt % of total dispersed phase showed an agglomerated structure formed between the aggregates. The SEM of the PP/PET binary fiber blends showed long well‐oriented microfibrils of PET whereas in the ternary blends, the microfibrils were found to have lower aspect ratio with a fraction of the SEBS stuck on the microfibril fracture surfaces. These results were attributed to a core‐shell type morphology in which the PET and SEBS formed the core‐shells distributed in the matrix. The melt viscoelastic behavior of the ternary blends containing less than 30 wt % of the total dispersed phase was found to be similar to the matrix and binary blend samples whereas the samples containing 30 and 40 wt % of dispersed phases exhibited a pronounced viscosity upturn and nonterminal storage modulus in low frequency range. These results were found to be in good agreement with the morphological results. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Effects of addition of functionalized SEBS on rheological,mechanical, and tribological properties of polyamide 6 nanocomposites

The effects of the addition of styrene‐ethylene/butylene‐styrene copolymer (SEBS) with various functionalized groups on the rheological, mechanical, and tribological properties on polyamide 6 nanocomposite filled with layered silicate (PA6/Clay) were investigated. Four types of SEBS: unmodified SEBS (SEBS), maleic anhydride grafted SEBS (SEBS‐g‐MA), amine group grafted SEBS (SEBS‐g‐NH₂), and carboxyl group grafted SEBS (SEBS‐g‐COOH) were added with PA6/Clay nanocomposite to prepare various polymer blends. These polymer blends were extruded by a twin screw extruder and injection molded. Dynamic viscoelastic properties of these blends in the molten state and their tensile, impact, and tribological properties were evaluated. The viscoelastic properties were found to increase with the addition of SEBS and were highly influenced by the types of functionalized groups contained. Influence of the addition of SEBS on the mechanical properties of these systems differed for each mechanical property. Although the tensile properties decreased with SEBS, Izod impact properties improved with the addition of various functionalized SEBS. These mechanical properties and viscoelastic properties correlated closely with the size of dispersed SEBS particles and interparticle distance. The tribological properties also improved with the addition of SEBS, and the influence of the amount added was higher than the type of SEBS used. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers