Thermal aging of bisphenol-A polycarbonate/acrylonitrile–butadiene–styrene blends

Thermal aging of immiscible bisphenol-A polycarbonate/acrylonitrile–butadiene–styrene (PC/ABS) blends containing 25, 60, and 75% PC and the PC and ABS blend components have been studied. Changes in Izod impact properties and dynamic mechanical spectra are reported following aging at 90, 110, and 130°C for times up to 1500 h. PC/ABS blends containing 60 and 75% PC were found to retain high impact performance following aging at elevated temperatures, compared to the PC blend component. Dynamic mechanical spectroscopy is an effective probe for investigating the structure–property changes occurring and the mechanisms of aging. For PC and ABS, the changes were mainly due to physical aging of the amorphous polymers when aged below the glass-transition temperature. For the PC/ABS blends, oxidative degradation additionally contributes to loss of toughness. Although structure–property changes are related to the behavior of the blend components, additional factors of potential importance for multiphase polymer–polymer systems have been identified, including a redistribution of stabilizers during the blend manufacture. © 1995 John Wiley & Sons, Inc.     

Recycling of blends of acrylonitrile–butadiene–styrene (ABS) and polyamide

The aim of this work is to evaluate routes to upgrade recycled engineering plastics, especially mixed plastics with acrylonitrile–butadiene–styrene copolymers (ABS) as the major component. A core‐shell impact modifier was successfully used to improve the impact strength of blends of ABS and ABS/polycarbonate (PC) blends recycled from the automotive industry. However, the presence of other immiscible components like polyamide (PA), even in small amounts, can lead to a deterioration in the overall properties of the blends. A styrene–maleic anhydride (SMA) copolymer and other commercial polymer blends were used to promote the compatibilization of ABS and PA. The core‐shell impact modifier was again found to be an efficient additive with regard to the impact strength of the compatibilized ABS/PA blends. The results obtained with fresh material blends were quite promising. However, in blends of recycled ABS and glass‐fiber‐reinforced PA, the impact strength did not exhibit the desired behavior. The presence of poorly bonded glass fibers in the blend matrix was the probable reason for the poor impact strength compared with that of a blend of recycled ABS and mineral‐filled PA. Although functionalized triblock rubbers (SEBS–MA) can substantially enhance the impact strength of PA, they did not improve the impact strength of ABS/PA blends because the miscibility with ABS is poor. The possibilities of using commercial polymer blends to compatibilize otherwise incompatible polymer mixtures were also explored giving promising results. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2535–2543, 2002     

Effect of styrene–isoprene–styrene,styrene–butadiene–styrene,and styrene–butadiene–rubber on the mechanical,thermal, rheological,and morphological properties of polypropylene/polystyrene blends

The mechanical, thermal, rheological, and morphological properties of polypropylene (PP)/polystyrene (PS) blends compatibilized with styrene–isoprene–styrene (SIS), styrene–butadiene–styrene (SBS), and styrene–butadiene–rubber (SBR) were studied. The incompatible PP and PS phases were effectively dispersed by the addition of SIS, SBS, and SBR as compatibilizers. The PP/PS blends were mechanically evaluated in terms of the impact strength, ductility, and tensile yield stress to determine the influence of the compatibilizers on the performance properties of these materials. SIS‐ and SBS‐compatibilized blends showed significantly improved impact strength and ductility in comparison with SBR‐compatibilized blends over the entire range of compatibilizer concentrations. Differential scanning calorimetry indicated compatibility between the components upon the addition of SIS, SBS, and SBR by the appearance of shifts in the melt peak of PP toward the melting range of PS. The melt viscosity and storage modulus of the blends depended on the composition, type, and amount of compatibilizer. Scanning electron microscopy images confirmed the compatibility between the PP and PS components in the presence of SIS, SBS, and SBR by showing finer phase domains. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 266–277, 2003     

Compatibility effect of radiation‐grafting‐functionalized styrene–butadiene–styrene on polyamide 6/styrene–butadiene–styrene blends

Styrene–butadiene–styrene (SBS) was grafted with dibutyl maleate (DBM), methacrylic acid (MAA), or maleic anhydride (MAH) by ⁶⁰Co γ‐rays. The grafted SBS was blended with polyamide 6 (PA6). The compatibility of the PA6/SBS blends was studied with scanning electron microscopy and rheological measurements. The results showed significant improvement in the compatibility of PA6 blended with MAH‐ or MAA‐grafted SBS, with the former being more effective, whereas grafting DBM was ineffective in this respect. Mechanisms of the compatibility enhancement and ineffectiveness are discussed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Boiling water aging of polycarbonate and polycarbonate/acrylonitrile–butadiene–styrene resin and polycarbonate/low‐density polyester blends

The effects of boiling water on the mechanical and thermal properties and morphologies of polycarbonate (PC), PC/acrylonitrile–butadiene–styrene resin (PC/ABS), and PC/low‐density polyester (PC/LDPE) blends (compositions of PC/ABS and PC/LDPE blends were 80/20) were studied. PC and the PC/ABS blend had a transition from ductile to brittle materials after boiling water aging. The PC/LDPE blend was more resistant to boiling water aging than PC and the PC/ABS blend. The thermal properties of glass‐transition temperature (T_g) and melting temperature (T_m) in PC and the blends were measured by DSC. The T_g of PC and PC in the PC/ABS and PC/LDPE blends decreased after aging. The T_g of the ABS component in the PC/ABS blend did not change after aging. The supersaturated water in PC clustered around impurities or air bubbles leading to the formation of microcracks, which was the primary reason for the ductile–brittle transition in PC, and the microcracks could not recover after PC was treated at 160°C for 6 h. The PC/ABS blend showed slightly higher resistance to boiling water than did PC. The highest resistance to boiling water of the PC/LDPE blend may be attributed to its special structural morphology. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 589–595, 2003     

Weld‐line characteristics of polycarbonate/acrylonitrile–butadiene–styrene blends. I. Effect of the processing temperature

The effects of the processing temperature on the morphology and mechanical properties at the weld line of 60/40 (w/w) polycarbonate (PC)/acrylonitrile–butadiene–styrene (ABS) copolymer blends were investigated. The influences of the incorporation of poly(methyl methacrylate) (PMMA) as a compatibilizer and an increase in the viscosity of the dispersed ABS domain phase were also studied. The ABS domain was well dispersed in the region below the V notch, and a coarse morphology in the core region was observed. When tensile stress was applied perpendicularly to the weld line, the fracture propagated along the weak region behind the weld part; there, the domain phase coalescence was significant because of the poor compatibility between PC and styrene–acrylonitrile (SAN). Phase coalescence became severe, and so the mechanical strength of the welded specimen decreased with an increasing injection‐molding temperature. The domain morphology became stable and the mechanical strength increased as the viscosity of the domain phase increased or some SAN was replaced with PMMA. That the morphology was well distributed behind the weld line and the mechanical properties of PC/ABS/PMMA blends were improved was attributed to the compatibilizing effect of PMMA. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 95: 689–699, 2005     

Mechanical,thermal, and morphological behavior of the polyamide 6/acrylonitrile–butadiene–styrene blends irradiated with gamma rays

Polymeric materials with improved properties can be obtained through polymer blends. As a polymer mixture is generally immiscible and incompatible, it is necessary to use compatibilizers to improve the interfacial adhesion. Polyamide 6 (PA‐6) is an attractive polymer to engineering applications; however, it reveals processing instability and relatively low‐notched impact strength. This behavior can be modified by blending with acrylonitrile–butadiene–styrene (ABS) copolymer. In this study, blends of PA‐6 with ABS were prepared using gamma irradiation, and the effects of ABS and ionizing radiation on the properties of PA‐6/ABS blends were investigated by differential scanning calorimetry (DSC), Fourier transform infrared (FTIR), X‐ray diffraction (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM) techniques. The data showed that the presence of ABS (30 wt%) in the blend decreased the tensile strength and elongation at break with respect to pure PA‐6. The decrease in the mechanical property was observed at doses 30 and 50 kGy. ABS showed strong effect on the crystallization of PA‐6 in the PA‐6/ABS binary blends. All irradiated blends are thermally more stable than those non‐irradiated. Chemical changes can be clearly seen in FTIR spectra through two bands assigned for N? H and OH? groups. POLYM. ENG. SCI., 2008. © 2007 Society of Plastics Engineers     

Effect of a nanoclay/triphenyl phosphate hybrid system on the fire retardancy of polycarbonate/acrylonitrile–butadiene–styrene blend

The effect of a hybrid system of nanoclay and triphenyl phosphate (TPP) on the fire retardancy of a polycarbonate (PC)/acrylonitrile–butadiene–styrene (ABS) blend was examined in this study. The nanoclay in the polymers decreased the peak heat release rates (PHRRs) with no significant effect on the ease of ignition and times to extinguishment. Improvements in the flame retardancy were observed only when nanoparticles were used with conventional flame‐retardant (FR) additives. Thermogravimetric analysis (TGA), cone calorimetry, and limited oxygen index (LOI)/UL 94 (Underwriters Laboratory) testing were used to investigate the thermal degradation, fire behavior, and flammability of the materials. The results show that when we used a combination of TPP and nanoclay as an FR system, degradation of the polymer blends was reduced as the TGA curves shifted to higher temperatures. PHRR in cone calorimetry testing decreased from 1032 kW/m² for the PC/ABS blend to 300 kW/m² for the PC/ABS/(12% TPP–2% nanoclay) sample, and the LOI increased from 23 to 35%, respectively. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Effect of the compatibilizers on flame-retardant polycarbonate (PC)/acrylonitrile–butadiene–styrene (ABS) alloy

Polycarbonate (PC) blended with acrylonitrile–butadiene–styrene (ABS) has the maximum notched Izod impact strength, which is 58 kg cm cm^-1 for PC/ABS1 and 66 kg cm cm^-1 for PC/ABS2, at a ratio of 80/20 in this study. We selected the ratio of 80/20 to prepare flame-retardant PC/ABS alloys. The compatibility of flame-retardant PC/ABS alloy was examined by differential scanning calorimetry (DSC). The flame-retardant PC/ABS alloy had two values of the glass transition temperature (T_g), indicating that the alloy was not compatible. Three kinds of compatibilizers, methacrylate–butadiene–styrene (MBS), ethylene–vinyl acetate (EVA), and styrene–maleic anhydride (SMA) were used to improve the phenomenon. DSC measurement revealed that after compatibilization the alloy had only one value of T_g, meaning that the alloy became more compatible. Samples were frozen in liquid nitrogen to look at their morphology. We found that the domain sizes were reduced and the surface boundaries were closed and blurred, a feature that could promote the mechanical properties of the alloy. In this study, we also compared the effects of mechanical properties on differential compatibilizers for the flame-retardant PC/ABS alloy. Cycoloy 2800 is a commercial-grade flame-retardant product and was chosen to compare it with our prepared alloys in this study. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 795-805, 1997     

Study of the influence of adding styrene–ethylene/butadiene–styrene in acrylonitrile–butadiene–styrene and polyethylene blends

This work studies the recovery of two grades of acrylonitrile–butadiene–styrene (ABS) contaminated with low‐density polyethylene (LDPE), by adding styrene–ethylene/butadiene–styrene (SEBS). To simulate contaminated ABS, virgin ABS was mixed with 1, 2, 4, and 8% of LDPE and then extruded at 220°C. After this, the ABS with the highest percentage of LDPE (8%) was mixed with 1, 2, 4, and 8% of SEBS and then extruded. Different blends were mechanically, rheologically, optically, and dimensionally characterized to study how different percentages of LDPE and SEBS modify their properties. The results obtained show how the tensile strength, Young modulus, elongation, and impact strength linearly decrease as the LDPE amount increases, for both natural and black ABS. Through the addition of SEBS to contaminated ABS, it is possible to improve its impact strength and elongation values nearly to those of virgin ABS. However, its tensile strength and Young modulus show no improvement, and even show a slight reduction. Regarding the rheological properties, the LDPE contamination in ABS causes a remarkable decrease in viscosity, and adding SEBS to the blend lowers its viscosity even further for both natural and black grades. This reduction is not a negative aspect, but rather quite the reverse, as the more fluid the material, the easier the mold injection process becomes. POLYM. ENG. SCI., 54:1313–1324, 2014. © 2013 Society of Plastics Engineers     

Amphiphilic styrene–butadiene–styrene triblock copolymer grafted with polyoxyethylene

A styrene–butadiene–styrene triblock copolymer (SBS) was grafted with polyoxyethylene via a ring‐opening reaction of an epoxidized styrene–butadiene– styrene triblock copolymer (ESBS) with monocarboxylic‐group‐terminated methoxypoly(ethylene glycol) (CMPEG). The latter was prepared through the esterification of methoxypoly(ethylene glycol) with maleic anhydride. The optimum conditions for the preparation of the graft copolymer were studied. The graft copolymer was characterized with Fourier transform infrared spectrophotometry. Its water absorbency, oil absorbency, emulsifying property, phase‐transfer catalysis property in the Williamson solid–liquid reaction, and use as a compatibilizer in the blending of SBS with oil‐resistant chlorohydrin rubber (CHR) were also studied. The optimum conditions were a CMPEG/epoxy group molar ratio of 1.5, an N,N‐dimethyl aniline/ESBS concentration of 5 wt %, and an ESBS concentration of 12–14 g/100 mL at 75–80°C for 10 h. The polyoxyethylene content could reach 0.27 mmol/g. The graft copolymer absorbed a certain amount of water, fairly resisted kerosene, and possessed good emulsifying and phase‐transfer catalysis properties, both of which were enhanced with increasing polyoxyethylene graft content. The graft copolymer could be used as a compatibilizer for a blend of SBS and CHR. A 3 wt % concentration of the graft copolymer based on a 50/50 blend could increase both the tensile strength and ultimate elongation of the blend about 1.7 times. The blend behaved like an oil‐resistant thermoplastic elastomer. Scanning electron microscopy demonstrated the improved compatibility of the two components by the graft copolymer. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Comparative investigation of the ultraviolet stabilization of polycarbonate/poly(acrylonitrile–butadiene–styrene) with different ultraviolet absorbers

When polycarbonate (PC)/poly(acrylonitrile–butadiene–styrene) (ABS) blends are exposed to outdoor conditions, they are mainly degraded by sunlight; this is known as photodegradation. It is the ultraviolet radiation in the sunlight that is responsible for the degradation of the blend. To stabilize the blend against the harmful ultraviolet radiation, ultraviolet absorbers (UVAs) are used. In this study, three different UVAs—Tinuvin 1577 (a hydroxyphenyl triazine type), Cyasorb 5411 (a benzotriazole type), and Uvinul 3030 (a cyanoacrylate type)—were compounded with a PC/ABS blend at 240°C with a twin‐screw extruder. Accelerated aging of the compounded sample was done by an Atlas Suntest containing xenon lamp. The degradation studies were performed with ultraviolet–visible spectroscopy, attenuated total reflectance/Fourier transform infrared spectroscopy, and yellowing index measurements. The molecular weight of the compounded sample was determined by gel permeation chromatography. It was found that hydroxyphenyl triazine type UVA showed the best results for decreasing the degradation products, oxidation rate, and yellowing of the PC/ABS blend. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Acrylonitrile–butadiene–styrene toughened nylon 6: The influences of compatibilizer on morphology and impact properties

Polymer alloys have been used as an alternative to obtain polymeric materials with unique physical properties. Generally, the polymer mixture is incompatible, which makes it necessary to use a compatibilizer to improve the interfacial adhesion. Nylon 6 (PA6) is an attractive polymer to use in engineering applications, but it has processing instability and relatively low notched impact strength. In this study, the acrylonitrile–butadiene–styrene (ABS) triblock copolymer was used as an impact modifier for PA6. Poly(methyl methacrylate‐co‐maleic anyhydride) (MMA‐MA) and poly(methyl methacrylate‐co‐glycidyl methacrylate) (MMA‐GMA) were used as compatibilizers for this blend. The morphology and impact strength of the blends were evaluated as a function of blend composition and the presence of compatibilizers. The blends compatibilized with maleated copolymer exhibited an impact strength up to 800 J/m and a morphology with ABS domains more efi8ciently dispersed. Moderate amounts of MA functionality in the compatibilizer (～5%) and small amounts of compatibilizer in the blend (～5%) appear sufficient to improve the impact properties and ABS dispersion. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 842–847, 2003     

Dynamic mechanical properties of polycarbonate and acrylonitrile–butadiene–styrene copolymer blends

Blends of polycarbonate (PC) and poly(acrylonitrile‐co‐butadiene‐co‐styrene) (ABS) with different compositions are characterized by means of dynamic mechanical measurements. The samples show phase separation. The shift in the temperatures of the main dynamic mechanical relaxation shown by the blend with respect to those of the pure components is attributed to the migration of oligomers present in the ABS toward the PC in the melt blending process. A comparison with other techniques (dielectric and calorimetric analysis) and the application of the Takayanagi three block model confirm this hypothesis. In all the studied blend compositions (ABS weight up to 28.6%) the PC appears as the matrix where a disperse phase of ABS is present. The scanning and transmission electron microscopy micrographs show that the size of the ABS particles increases when the proportion of ABS in the blend increases. The FTIR results indicate that the interaction between both components are nonpolar in nature and can be enhanced by the preparation procedure. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1507–1516, 2002     

Effect of maleic anhydride grafted polybutadiene on the compatibility of polyamide 66/acrylonitrile‐butadiene‐styrene copolymer blend

The addition of maleic anhydride grafted polybutadiene (PB‐g‐MAH) can greatly improve the compatibility of polyamide 66 (PA66)/acrylonitrile‐butadiene‐styrene copolymer (ABS) blends. Unlike the commonly used compatibilizers in polyamide/ABS blends, PB‐g‐MAH is compatible with the ABS particles' core phase polybutadiene (PB), rather than the shell styrene‐acrylonitrile (SAN). The compatibility and interaction of the components in the blends were characterized by Fourier transform‐infrared spectra (FTIR), Molau tests, melt flow index (MFI), dynamic mechanical analyses (DMA), and scanning electron microscopic (SEM) observations. The results show that PB‐g‐MAH can react with the amino end groups in PA66 while entangle with the PB phase in ABS. In this way, the compatibilizer anchors at the interface of PA66/ABS blend. The morphology study of the fracture sections before and after tensile test reveals that the ABS particles were dispersed uniformly in the PA66 matrix and the interfacial adhesion between PA66 and ABS was increased significantly. The mechanical properties of the blends thus were enhanced with the improving of the compatibility. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers     

Melt processing,mechanical, and fatigue crack propagation properties of reactively compatibilized blends of polyamide 6 and acrylonitrile–butadiene–styrene copolymer

Within a IUPAC study, melt processing, mechanical, and fatigue crack growth properties of blends of polyamide 6 (PA 6) and poly(acrylonitrile–butadiene–styrene) (ABS) were investigated. We focused on the influence of reactive compatibilization on blend properties using a styrene–acrylonitrile–maleic anhydride random terpolymer (SANMA). Two series of PA 6/ABS blends with 30 wt % PA 6 and 70 wt % PA 6, respectively, were prepared with varying amounts of SANMA. Our experiments revealed that the morphology of the matrix (PA 6 or ABS) strongly affects the blend properties. The viscosity of PA 6/ABS blends monotonically increases with SANMA concentration because of the formation of high‐molecular weight graft copolymers. The extrudate swell of the blends was much larger than that of neat PA 6 and ABS and decreased with increasing SANMA concentrations at a constant extrusion pressure. This observation can be explained by the effect of the capillary number. The fracture resistance of these blends, including specific work to break and impact strength, is lower than that of PA 6 or ABS alone, but increases with SANMA concentration. This effect is most strongly pronounced for blends with 70 wt % PA 6. Fatigue crack growth experiments showed that the addition of 1–2 wt % SANMA enhances the resistance against crack propagation for ABS‐based blends. The correlation between blend composition, morphology and processing/end‐use properties of reactively compatibilized PA 6/ABS blends is discussed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Novel method for preparation of quaternary ammonium ionomer from epoxidized styrene–butadiene–styrene triblock copolymer and its use as compatibilizer for blending of styrene–butadiene–styrene and chlorosulfonated polyethylene

A novel method for the preparation of a quaternary ammonium ionomer of styrene–butadiene–styrene triblock copolymer (SBS) was developed by a ring‐opening reaction of epoxidized SBS with triethylamine hydrochloride in the presence of a phase transfer catalyst. The optimum conditions were studied. The ionomer was characterized by quantitative analysis, IR spectroscopy, and ¹H‐NMR spectroscopy. Its water absorbency, oil absorbency, dilute solution viscosity, and use as a compatibilizer for the blending of SBS and chlorosulfonated polyethylene (CSPE) were investigated. The results showed that, under optimum conditions, the epoxy groups can be completely converted to the quaternary ammonium groups. The IR spectrum did not exhibit the absorption peak for quaternary ammonium groups, whereas the ¹H‐NMR spectrum and titration method demonstrated it. With increasing ionic group content, the water absorbency of the ionomer increased whereas its oil absorbency decreased. These indicated the amphiphilic character of the SBS ionomer. The dilute solution viscosity of the ionomer in toluene/methanol (9/1) solvent increased with increasing quaternary ammonium group content. The ionomer was used as a compatibilizer for the blends of SBS and CSPE. The addition of a small amount of the ionomer to the blend enhanced the mechanical properties of the blends: 2 wt % ionomer based on the blend increased the tensile strength and ultimate elongation of the blend nearly 2 times. The blends of equal parts SBS and CSPE behaved as oil‐resistant thermoplastic elastomers. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1975–1980, 2006     

Morphology of pyrolyzed polystyrene–isoprene–styrene and polystyrene–butadiene–styrene block copolymers

The surface morphology of thermooxidative‐degraded polystyrene–isoprene–styrene (SIS) and polystyrene–butadiene–styrene (SBS) thermoplastic block copolymers were studied by scanning electron microscopy. Surface changes caused by heating the samples in a pyrolizer for 15 and 30 min were presented in different micrographs. The morphological changes occurring due to the formation of polar groups and their crossing linking during the thermooxidative degradation are discussed. Morphological study of these thermally degraded polymer samples show very good correlation with the thermodegradation results. The rate of thermodegradation is fast in case of SBS compared with SIS block copolymer. ©2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Modification of poly(lactic) acid by reactive extrusion and its melt blending with acrylonitrile–butadiene–styrene

Poly(lactic) acid (PLA) is a biodegradable polymer that has attracted interest as a potential substitute for some thermoplastic polymers. However, its advanced brittleness at room temperature represents one of the major drawbacks for its general use. In this work, PLA was modified by reactive extrusion (PLA_REx) to enhance the rheological behaviour and to limit its degradation. The modified material was melt blended with acrylonitrile–butadiene–styrene (ABS), and the resultant morphology, rheological, thermo‐mechanical and fracture behaviour were analysed. Since PLA does not have reasonable compatibility with ABS, maleic‐anhydride‐grafted ABS (ABS‐g‐Ma) was used as compatibilizer. The morphology of the PLA_REx/ABS samples resulted in the formation of small ABS rods in the matrix. The presence of maleic anhydride contributed to reducing the interfacial energy of the blends and to obtaining finer micro‐domains of the ABS‐rich phase in the PLA_REx matrix. In the compatibilized blends, the presence of elongated ABS‐rich phases opposed free crack propagation and contributed to the increase in fracture energy in comparison to neat PLA. © 2020 Society of Chemical Industry     

Morphology of pyrolysed polystyrene–isoprene–styrene and polystyrene–butadiene–styrene block copolymers

The surface morphology of thermooxidative degraded polystyrene–isoprene–styrene (SIS) and polystyrene–butadiene–styrene (SBS) thermoplastic block copolymers was studied by scanning electron microscopy. Surface changes caused by heating the samples in a pyrolyzer for 15 and 30 min were presented in different micrographs. The morphological changes occurring due to the formation of polar groups and their crosslinking during the thermooxidative degradation are discussed. Morphological study of these thermally degraded polymer samples shows very good correlation with the thermodegradation results. The rate of thermodegradation is fast in case of SBS when compared with SIS block copolymer. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 2549–2553, 2006