Rheological and mechanical properties of compatibilized polystyrene/ethylene vinyl acetate blends

In this study, a blend of polystyrene (PS)/ethylene vinyl acetate (EVA) (PS/EVA, 90 : 10 wt %) was compatibilized with three different block copolymers, in which their end blocks were compatible with either styrene or EVA. The compatibilized blends with different compositions were prepared using a twin‐screw extruder and injection molded into the required test specimens. Mechanical properties of the blends, such as tensile properties and Charpy impact strength, morphology of tensile fractured surfaces, rheological properties, and thermal properties, were investigated. The results show that the interaction between the dispersed and continuous phase can be improved by the addition of a compatibilizer. Appreciable improvement in the impact strength of the blend with 15 wt % of compatibilizer C (polystyrene‐block‐polybutadiene) was observed. Its mechanical properties are comparable to those of the commercial high‐impact polystyrene, STYRON 470. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2071–2082, 2004     

Mechanical,thermal, and morphological characteristics of compatibilized and dynamically vulcanized polyoxymethylene/ethylene propylene diene terpolymer blends

Dynamically vulcanized blends of polyoxymethylene (POM) and ethylene propylene diene terpolymer (EPDM) with and without compatibilizer were prepared by melt mixing in a twin screw extruder. Maleic anhydride (MAH) grafted EPDM (EPDM‐g‐MAH) has been used as a compatibilizer. Dicumyl peroxide was used for vulcanizing the elastomer phase in the blends. Mechanical, dynamical mechanical, thermal, and morphological properties of the blend systems have been investigated as a function of blend composition and compatibilizer content. The impact strength of both dynamically vulcanized blends and compatibilized/dynamically vulcanized blends increases with increase in elastomer content with decrease in tensile strength. Dynamic mechanical analysis shows decrease in tanδ values as the elastomer and compatibilizer content increased. Thermograms obtained from differential scanning calorimetric studies reveal that compatibilized blends have lower T_m values compared to dynamically vulcanized blends, which confirms strong interaction between the plastic and elastomer phase. Scanning electron microscopic observations on impact fractured surface indicate reduction in particle size of elastomer phase and its high level of dispersion in the POM matrix. In the case of compatibilized blends high degree of interaction between the component polymers has been observed. POLYM. ENG. SCI., 47:934–942, 2007. © 2007 Society of Plastics Engineers     

Study of the properties of compatibilized ABS/PA6 blends using response surface methodology

Styrene‐(maleic anhydride) copolymer (SMA) compatibilized blends of acrylonitrile‐butadiene rubber (ABS) and polyamide 6 (PA6) with a variety of compositions and compatibilizer levels were prepared at various screw speeds in a corotating twin screw extruder. A Box–Behnken model for three variables, with three levels, was chosen as an experimental design, and the mechanical properties of the blends were considered as the responses. Each response was analyzed and formulated versus the considered factors by the use of response surface methodology. Impact resistance increased with increased SMA concentration and reduced screw speed. In compatibilized samples, with an increase in PA6 content, higher impact resistance was observed. Increasing PA6 content and SMA concentration, as well as decreasing screw speed, gave improvements in both tensile and flexural strengths. In each case, all of the correlations among factors were studied. Grafting of SMA was proved by detecting the graft copolymer (SMA‐PA6) formed through extraction in formic acid and FTIR spectroscopy. Compared with uncompatibilized blends, compatibilized samples displayed more uniform and finer particle sizes, thereby proving the compatibilizing effect of the graft copolymer. The asymmetry trend in dispersed particle size before and after the phase inversion became more differentiated in the presence of the compatibilizer. Adding SMA lowered the phase inversion composition (based on PA6), whereas higher screw speed increased it. J. VINYL ADDIT. TECHNOL., 2009. © 2009 Society of Plastics Engineers     

Effect of processing parameters on the mechanical properties of in situ compatibilized polybutylene terephthalate/acrylonitrile–butadiene–styrene blends

To evaluate mechanical properties of blends prepared by intermeshing corotating twin‐screw extrusion (ICTSE), it is usually necessary to injection mold specimens after the extrusion mixing process. At this study an alternative method is used to obtain testing specimens from ribbons extruded polybutylene terephthalate/acrylonitrile–butadiene–styrene blends, (PBT/ABS), compatibilized with methyl methacrylate–glycidyl methacrylate‐ethyl acrylate (MGE) by ICTSE, and then to correlate their mechanical properties with the processing parameters. Regarding to the extrusion process parameters, it has been noted that higher feed rates, lower screw speeds and narrower kneading blocks have reduced the ductile‐brittle transition temperature (DBTT) of the compatibilized PBT/ABS blends, thereby suggesting that the molecule integrity of blend polymeric components has been preserved and that a good dispersion of the ABS domains in the PBT matrix has been achieved. Injection molded PBT/ABS blends were obtained to compare to the extruded ribbons. The mechanical tests for both specimens have shown the same trends. The injection molded samples have presented poorer impact strength, tensile strain at break and tensile strength, when compared to the respective extruded samples. That behavior has been attributed to the high level of molecular orientation resulting from the injection molding process and mainly to PBT degradation during process. The PBT degradation could have increased its degree of crystallinity, which has been confirmed by DSC measurements. As result, the blend became more brittle, decreasing its Izod impact strength. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Morphology and mechanical properties of reactive compatibilized polystyrene/ethylene‐vinyl acetate‐vinyl alcohol blends

A reactive compatibilizer, styrene‐maleic anhydride (SMA) was used to compatibilize the blends of polystyrene (PS) and ethylene‐vinyl acetate‐vinyl alcohol (EVAOH), which was synthesized from ethylene‐vinyl acetate (EVA) using transesterification reaction. The compatibilized blends with different compositions were prepared using a twin‐screw extruder and injection molded into the required test specimens. Morphology of Charpy impact‐fractured surfaces, tensile, and impact properties of the blends were investigated. Fourier‐transform infrared spectroscopy (FTIR) was also applied for specific samples to elucidate the presence of the functional groups reaction necessary for reactive compatibilization. The results of the ternary PS/EVAOH/SMA blends illustrate that the addition of SMA as a compatibilizer slightly reduce the elongation at break. From the impact‐fractured surfaces of the blends, it is evident that the morphology developed sizable pores when SMA was added into the blends. This might be attributed to the residual octanol‐1, produced from the synthesis of EVAOH, as there is a possibility of a reaction between hydroxyl groups in the octanol‐1 and the anhydride groups in the SMA. This disrupted the stability of the morphology and resulted in the decrease in the elongation, and hence, the tensile toughness. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 209–217, 2002     

Melt-neutralization of maleic anhydride grafted on high-density polyethylene compatibilizer for polyamide-6/high-density polyethylene blend: effect of neutralization level on compatibility of the blend

Blends of polyamide-6 (PA-6) and high-density polyethylene (HDPE) with blend ratios of 80/20 (wt/wt) and 20/80 (wt/wt) were studied using zinc-neutralized maleic anhydride (MAH) grafted HDPE as compatibilizers. MAH groups were hydrolyzed and neutralized with different amounts of zinc acetate dihydrate in a twin-screw extruder to produce different levels of zinc-neutralization (0, 14, 41, 69, and 95 %) at one and ten parts per hundred of resin of compatibilizer. Melt neutralization of MAH was confirmed by X-ray fluorescence, FT–IR, and rheological properties. SEM micrographs showed a large reduction in the dispersed phase size in the compatibilized blends. Tensile measurements showed improvement of tensile strength for all compatibilized blends; moreover, the elongation at break of compatibilized blends at 10 phr of compatibilizer was improved. Blending increased the crystallization temperature for the PA-6, and the addition of compatibilizer reduced the crystallization temperature slightly. A significant increase in melt viscosity of the compatibilizer was found with zinc addition and adding compatibilizer increased the viscosity of the blends. However, the addition of zinc to the compatibilizer did not change the viscosity in the PA-6-rich blends and actually led to a decrease in viscosity in the HDPE-rich blends.     

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     

Compatibilization of PE/PS and PE/PP blends. I. Effect of processing conditions and formulation

The objective of this work was to study the effectiveness of low‐cost commercial compatibilizers and several processes (internal mixer, single‐ and twin‐screw extruders) for two types of plastic blends: high‐density polyethylene/polypropylene and high‐density polyethylene/polystyrene blends, to gain insight into the recycling of wastes from those frequently encountered mixed plastics. Blends going from a pure A to a pure B component, with and without a compatibilizer, were prepared using an internal mixer, a corotating twin‐screw extruder, as well as a single‐screw extruder to follow an industrial‐convenient process. In both cases, the analyses of blend morphologies highlighted the poor adherence between the two phases in the uncompatibilized blends. Compatibilized blends display better adherence between phases and the ability to process blends made from both single‐ and twin‐screw extruders. When adding a compatibilizer, the viscosity of each blend (PE/PP or PE/PS) increased due to a better adhesion of the phases. Charpy impact tests showed that the presence of the compatibilizer in PE/PS blends increased their impact properties. Indeed, the improvement of the adhesion between the two phases enabled stress transfer at the interface. A single‐screw extruder seems to be efficient as a processing method on an industrial scale when a compatibilizer is used. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2475–2484, 2003     

Properties and preparation of compatibilized nylon 6 nanocomposites/ABS blends using functionalized metallocene polyolefin elastomer. I. Impact properties

The impact behaviors of nanoclay‐filled nylon 6 (nano‐nylon 6) blended with poly(acrylonitrile–butadiene–styrene) terpolymers (ABS) prepared through a twin screw mixing process were investigated here using metallocene polyethylene grafted maleic anhydride (POE‐g‐MA) as a compatibilizer to enhance the interface interaction. No clear effect of compatibilizer on the dispersion of clay and crystalline structure of nano‐nylon 6 has been observed. In view of morphology and rheological behaviors, the effect of compatibilizer on the mechanical properties could be elucidated. It is found that impact strength increases with the addition of compatibilizer at various ABS compositions. Similar effects are also observed with decreasing test temperature at the nano‐nylon 6/ABS blend composition of 80/20. As for thermal properties, the heat distortion temperature shows a marginal decrease in the nano‐nylon 6/ABS blends. Rheological behavior indicates that increased viscosity is found for the investigated compatibilized systems. Through morphology observations, the etched ABS particle sizes tend to decrease with the addition of compatibilizer for the blends, but are larger with higher contents of ABS concentrations. Those observations account for impact behaviors of the investigated blends. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1364–1371, 2006     

Engineering properties of compatibilized polypropylene/liquid crystalline polymer blends

Polypropylene (PP) and Vectra A950, a thermotropic liquid crystalline polymer (LCP), blends were prepared in a single‐screw extruder with the variation in Vectra A950 content in presence of fixed amount (2%, with respect to PP and LCP mixture as a whole) of ethylene‐acrylic acid (EAA) copolymer as a compatibilizer. Mechanical analysis of the compatibilized blends within the range of LCP incorporations under study (2–10%) indicated pronounced improvement in the moduli, ultimate tensile strength (UTS), and hardness. Fourier transform infrared (FTIR) spectroscopy studies revealed the presence of strong interaction through H‐bonding between the segments of Vectra A950 and the compatibilizer EAA. Morphological studies performed by scanning electron microscopy (SEM) manifested the development of fine fibrillar morphology in the compatibilized PP/Vectra A950 blends, which had large influence on the mechanical properties. Differential scanning calorimetry studies showed an initial drop of the melting point of PP in the presence of EAA followed by enhancement of the same in presence of Vectra A950. TGA showed an increase in the thermal stability for all blends with respect to matrix polymer PP. Rheological studies showed that a very small quantity of Vectra A 950 was capable of reducing the melt viscosity of PP particularly in the lower shear rate region and hence facilitated processibility of the blends. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Compatibilizers for thermotropic liquid crystalline polymer/polyethylene blends prepared by reactive mixing

This paper describes the effects of composition and processing conditions on the efficiency of the compatibilizer prepared from a thermotropic liquid crystalline polymer (TLCP) and the sodium salt of a poly(ethylene‐co‐r‐acrylic acid) ionomer (EAA‐Na) in TLCP/low‐density polyethylene (LDPE) blends and TLCP/high‐density polyethylene (HDPE) blends. The TLCP‐ionomer graft copolymer formed by a melt acidolysis reaction effectively reduced the interfacial tension between TLCP and polyethylene, which improved impact strength and toughness of the compatibilized blends. Higher processing temperatures for the reactive extrusion produced a more efficient compatibilizer, presumably due to increased graft‐copolymer formation, but the reaction temperature had little effect on the impact strength of compatibilized blends for temperatures above 300°C. The addition of the compatibilizer to TLCP/LDPE blends significantly increased the melt viscosity due to increased interfacial adhesion. The TLCP/EAA‐Na ratio used to prepare the compatibilizer had little effect on the performance of the compatibilizer. Although the compatibilizer can be prepared in situ by blending and extruding a ternary blend of TLCP/EAA‐Na/polyethylene, pre‐reacting the compatibilizer resulted in blends with improved toughness and elongation.     

Compatibilizers based on polypropylene grafted with itaconic acid derivatives. Effect on polypropylene/polyethylene terephthalate blends

New types of compatibilizers based on functionalized polypropylene (PP) were synthesized by radical melt grafting either with monomethyl itaconate or dimethyl itaconate. The effect of these new modified PP compounds were tested as compatibilizers in PP/polyethylene terephthalate (PET) blends. Blends with compositions 15/85 and 30/70 by weight of PP and PET were prepared in a single‐screw extruder. Morphology of the compatibilized blends revealed a very fine and uniform dispersion of the PP phase as compared with that of noncompatibilized blends of the same composition, leading to improved adhesion between the two phases. Whereas dimethyl itaconate derived agent showed less activity, the monomethyl itaconate parent compound showed an increase of the impact resistance of PET in PP/PET blend. This was attributed to the hydrophilic nature of the monomethyl itaconate part of this compatibilizer. The tensile strength of PET in noncompatibilized blends gradually decreases as the PP content increases, while blends containing functionalized PP exhibited higher values.     

Studies on morphology,mechanical, thermal,and dynamic mechanical behavior of extrusion blended polypropylene and thermotropic liquid crystalline polymer in presence of compatibilizer

Polypropylene was melt blended in a single screw extruder with thermo tropic Vectra B‐950 liquid crystalline polymer (copolyester amide) in different proportions in presence of 2% of EAA, ethylene‐acrylic acid copolymer (based on PP) as a compatibilizer. The mechanical properties of such compatibilized blends were evaluated and compared in respect of their Young's Modulii, Ultimate tensile strength, percent elongation at break, and toughness to those of Pure PP. The Morphology was studied by using a polarizing light microscope (PLM) and Scanning electron microscope (SEM). The Thermal characterization of these blends were carried out by differential scanning calorimeter (DSC).The mechanical properties under dynamic conditions of such compatibilized blends and pure PP were studied by dynamic mechanical analyzer (DMA). Mechanical analysis (Tensile properties) of the compatibilized blends displayed improvements in Modulii and ultimate tensile strength (UTS) of PP matrix with the incorporation of 2–10% of LCP incorporation. The development of fine fibrillar morphology in the compatibilized PP/LCP blends had large influence on the mechanical properties. Differential scanning calorimeter (DSC) studies indicated no remarkable changes in the crystalline melting temperature of the blends with respect to that of pure PP. However, an increase in the softening range of the blends over that of PP was observed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Amphiphilic block copolymers of PtBA‐b‐PMMA as compatibilizers for blends of PET and PMMA

PET and PMMA were blended at various weight fractions. These blends were compatibilized by employing amphiphilic block copolymers of PtBA‐b‐PMMA, having three compositions (1:3, 1:1, 3:1) and three weight fractions (3, 5, and 7 wt%) using a co‐rotating twin screw extruder. The blends were evaluated for their mechanical, rheological, and morphological properties. Overall, the compatiblized blends showed improvement in properties compared with the properties of noncompatiblized blends. Mechanical properties of the compatibilized blends improved with an increase in the PMMA and compatibilizer weight fractions. It was observed that the compatibilizer with lower molecular weight and lower glass transition temperature, typically at 5 wt%, provided the overall best properties. POLYM. ENG. SCI. 46:1147–1152, 2006. © 2006 Society of Plastics Engineers.     

Preparation and characterization of thermoplastic starch/PLA blends by one‐step reactive extrusion

In the presence of dicumyl peroxide, the compatibility of thermoplastic dry starch (DTPS)/poly(lactic acid) (PLA) blends, using maleic anhydride (MA) as compatibilizer, was investigated. The plasticization of starch and its compatibilizing modification with PLA was accomplished in a single‐screw extruder by one‐step reactive extrusion. In the presence of MA, the plasticization of starch in DTPS/PLA blends could be improved and homogeneous DTPS/PLA blends could be achieved as observed using scanning electron microscopy. Tensile tests showed that the tensile strength of compatibilized DTPS/PLA blends was about 40.5 MPa higher than that of the original composites. Differential thermal analysis indicated that the glass transition temperature of DTPS and PLA became closer in the presence of MA than the blend without any additions, which suggested the compatibility between DTPS and PLA was improved. In addition, Fourier transform infrared spectroscopy proved that MA improved the interaction between DTPS and PLA. At the same time, the blend became more thermally stable as shown by thermogravimetric analysis results. A novel decomposition peak at about 450 °C was detected in the compatibilized blend, which was higher than those observed for DTPS and PLA. Finally, a rheological study suggested that MA could improve the fluidity of DTPS/PLA blends. Copyright © 2007 Society of Chemical Industry     

Mechanical properties and morphology of PP/ABS blends compatibilized with PP‐g‐2‐HEMA

Polypropylene (PP) and acrylonitrile–butadiene–styrene blends of different composition were prepared using a single‐screw extruder. The binary blend of PP/ABS was observed to be incompatible and shows poor mechanical properties. PP‐g‐2‐hydroxyethyl methacrylate (2‐HEMA) was used as a compatibilizer for the PP/ABS blends. The ternary compatibilized blends of PP/ABS/PP‐g‐2‐HEMA showed improvement in the mechanical properties. Electron micrographs of these blends showed a homogeneous and finer distribution of the dispersed phase. The mechanical performance increased particularly in the PP‐rich blend. The 2.5‐phr (part per hundred of resin) compatibilizer was observed to bring improvement to the properties. The suitability of various existing theoretical models for the predication of the tensile moduli of these blends was examined. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 72–78, 2003     

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     

Effect of the compatibilizer on the morphology and properties of dynamically cured PP/POE/epoxy blends

Dynamic vulcanization was successfully applied to epoxy resin reinforced polypropylene (PP)/ethylene‐octene copolymer (POE) blends, and the effects of different compatibilizers on the morphology and properties of dynamically cured PP/POE/epoxy blends were studied. The results show that dynamically cured PP/POE/epoxy blends compatibilized with maleic anhydride‐grafted polypropylene (MAH‐g‐PP) have a three‐phase structure consisting of POE and epoxy particles dispersed in the PP continuous phase, and these blends had improved tensile strength and flexural modulus. While using maleic anhydride‐grafted POE (MAH‐g‐POE) as a compatibilizer, the structure of the core‐shell complex phase and the PP continuous phase showed that epoxy particles could be embedded in MAH‐g‐POE in the blends, and gave rise to an increase in impact strength, while retaining a certain strength and modulus. DSC analysis showed that the epoxy particles in the blends compatibilized with MAH‐g‐PP were more efficient nucleating agents for PP than they were in the blends compatibilized with MAH‐g‐POE. WAXD analysis shows that compatibilization do not disturb the crystalline structure of PP in the blends. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

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     

Phase morphology development during processing of compatibilized and uncompatibilized PBT/ABS blends

The development of the multiphase morphology of uncompatibilized blends of poly(butylene terephthalate) (PBT) and acrylonitrile–butadiene–styrene terpolymer (ABS) and PBT/ABS blends compatibilized with methyl‐methacrylate glycidyl‐methacrylate (MMA‐GMA) reactive copolymers during compounding in a twin‐screw extruder and subsequent injection molding was investigated. Uncompatibilized PBT/ABS 60/40 (wt %) and compatibilized PBT/ABS/MMA‐GMA with 2 and 5 wt % of MMA‐GMA showed refined cocontinuous morphologies at the front end of the extruder, which coarsened towards the extruder outlet. Coarsening in uncompatibilized PBT/ABS blends is much more pronounced than in the compatibilized PBT/ABS/MMA‐GMA equivalents and decreases with increasing amounts of the MMA‐GMA. For both systems, significant refinement on the phase morphology was found to occur after the blends pass through the extruder die. This phenomenon was correlated to the capacity of the die in promoting particles break‐up due to the extra elongational stresses developed at the matrix entrance. Injection molding induces coarsening of the ABS domains in the case of uncompatibilized PBT/ABS blends, while the reactive blend kept its refined phase morphology. Therefore, the compatibilization process of PBT/ABS/MMA‐GMA blends take place progressively leading to a further refinement of the phase morphology in the latter steps, owing to the slow reaction rate relative to epoxide functions and the carboxyl/hydroxyl groups. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 102–110, 2007