Reactive extrusion of in-situ composite based on PET and LCP blends

The “in-situ” compatibilization for a PET/LCP blend via transesterification reactions in a twin-screw extruder having a very short residence time is investigated through thermal, rheological, and mechanical studies. Inclusion of a small amount of liquid crystalline polymer (LCP) enhanced the crystallization rate of the poly(ethylene terephthalate) (PET) matrix. It acted as a nucleating agent. LCP lowered the blend viscosity above T_cn (crystalline-nematic transition temperature), working as a processing aid. However, the addition of dibutyltindilaurate (DBTDL) as a reaction catalyst was found to increase the viscosity of the blends, diminish the size of the dispersed phase, enhance its adhesion with the matrix, and lead to an increase of mechanical properties of two immiscible phases. Hence DBTDL is helpful in producing a reactive compatibilizer by reactive extrusion at the interface of this polyester blend system. The optimum catalyst amount turned out to be about 500 ppm when the reaction proceeds in 90/10 PET/LCP polyester blend systems. Its effect on the mechanical properties is discussed in detail. The structural change of reactive blend was identified by H¹ NMR and wide angle X-ray diffraction patterns.     

Morphology and mechanical properties of liquid crystalline copolyester and poly(ethylene 2,6-naphthalate) blends

Blends of poly(ethylene 2,6-naphthalate) (PEN) and a liquid crystalline copolyester (LCP), poly(benzoate-naphthoate), were prepared in a twin-screw extruder. Specimens for mechanical testing were prepared by injection molding. The morphology and mechanical properties were investigated by scanning electron microscopy (SEM) and an Instron tensile tester. SEM studies revealed that finely dispersed spherical domains of the liquid crystalline polymer (LCP) were formed in the PEN matrix, and the inclusions were deformed into fibrils from the spherical droplets with increasing LCP content. The morphology of the blends was found to be affected by their composition and a distinct skin-core morphology was found to develop in the injection molded samples of these blends. Mechanical properties were improved with increasing LCP content, and synergistic effects have been observed at 70 wt% LCP content whereas the elongation at break was found to be reduced drastically above 10 wt% of LCP content. This is a characteristic typical of chopped-fiber-filled composites. The improvement in mechanical properties is likely due to the reinforcement of the PEN matrix by the fibrous LCP phase as observed by scanning electron microscopy. The tensile and modulus mechanical behavior of the LCP/PEN blends was very similar to those of the polymeric composite, and the tensile strength and flexural modulus of the LCP/PEN 70/30 blend were two times the value of PEN homopolymer and exceeded those of pure LCP, suggesting LCP acts as a reinforcing agent in the blends.     

Rheology and thermal properties of liquid crystalline copolyester and poly(ethylene 2,6-naphthalate) blends

Blends of a poly(ethylene 2,6-naphthalate) (PEN) and a liquid crystalline copolyester (LCP), poly(benzoate-naphthoate) were prepared in a twin-screw extruder. Specimens for thermal properties were investigated by means of an instron capillary rheometer (ICR) and scanning electron microscopy (SEM). The blend viscosity showed a minimum at 10 wt% of LCP and increased with increasing LCP content above 10 wt% of LCP. Above 50% of LCP and at higher shear rate, phase inversion occured and the blend morphology was fibrous and similar to pure LCP. The ultimate fibrillar structure of LCP phase appeared to be closely related to the extrusion temperature. By employing a suitable deformation history, the LCP phase may be elongated and oriented such that a microfibrillar morphology can be retained in the solid state. Thermal properties of the LCP/PEN blends were studied using DSC and a Rheovibron viscoelastomer. These blends were shown to be incompatible in the entire range of the LCP content. For the blends, the T_g and Tm were unchanged. The half time of crystallization for the LCP/PEN blends decreased with increasing LCP content. Therefore, the LCP acted as a nucleating agent for the crystallization of PEN. The dimensional and thermal stability of the blends were increased with increasing LCP content. In studies of dynamic mechanical properties, the storage modulus (E′) was improved with increasing LCP content and synergistic effects were observed at 70 wt% of LCP content. The storage modulus for the LCP/PEN 70/30 blend is twice that of PEN matrix and exceeded pure LCP.     

In situ reactive compatibilized noryl/LCP blends

This article reveals that the already known improved properties of the thermoplastic–liquid crystalline polymer (LCP) blends can be further improved substantially over the corresponding noncompatibilized counterparts by using a reactive in situ type compatibilizer, the styrene–glycidyl methacrylate (SG) copolymer. This SG copolymer has been demonstrated in this article to be an effective reactive compatibilizer to improve the processability, heat deflection temperature, and mechanical properties of Noryl/LCP blends. The epoxy functional groups of the SG copolymer can react with the end groups of PPO (in Noryl) and LCP. The in situ-formed SG–g–LCP copolymer tends to reside along the interface of Noryl–LCP and reduces the interfacial tension during melt processing. The resultant LCP fibers in the Noryl matrix of the compatibilized blends have a higher aspect ratio because the fibers become finer, longer, and tend to form lamellate domains with a greater interphase contact area than those from the noncompatibilized blends. The compatibilized blends also improve the interphase adhesion between Noryl and LCP. The presence of ethyl triphenylphosphonium bromide catalyst promotes the grafting reaction to improve blend compatibilization. © 1995 John Wiley & Sons, Inc.     

Spinnability and physical properties of in situ composite fibers based on thermotropic liquid crystalline polymer

In situ composite fibers based on poly(ethylene 2,6‐naphthalate) (PEN) and a thermotropic liquid crystalline polymer (Vectra A950) were prepared using a single‐screw extruder. The fibers were taken up at selected speeds. The spinnability, thermal behavior, mechanical properties, and morphologies of the PEN/Vectra A950 blend were investigated. The results showed that the PEN/Vectra A950 blends were partly miscible, and the miscibility increased with the increased concentration of Vectra in the blend. The DSC measurements indicated that Vectra enhanced the crystallization process of PEN by performing as a nucleating agent. The Instron tensile property study, coupled with scanning electron microscopy, revealed that the mechanical properties of the PEN matrix were significantly improved when Vectra existed as long and continuous fibrils. The laser Raman results showed that the Vectra orientation began to develop at take‐up speeds above 500 m/min. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 795–811, 2002     

Reactive blends of epoxy resin (DGEBA) crosslinked by anionically polymerized polycaprolactam. II. Mechanical and electrical properties

Various reactive blends of diglycidyl ether of bisphenol A (DGEBA)/polycaprolactam were synthesized by anionic polymerization at 140°C, conducted by sodium hydride catalyst, a strong base, along with N‐acetyl caprolactam as a cocatalyst. The experiments were performed to study the effect of composition on the mechanical and electrical properties of the reactive blends, such as tensile properties, flexural properties, Izod impact strength, Rockwell hardness, and volume resistivity. It was observed that the DGEBA was crosslinked by the polycaprolactam through the rapid reaction of the oxirane group with amide nitrogen. The heat of reaction and heat‐deflection temperature of the reactive blends increased with increasing DGEBA content from 50 to 80 wt %, and increased dramatically above 70 wt % DGEBA content. The mechanical and electrical properties of the reactive blends increased with increasing DGEBA content from 50 to 80 wt %. Substantial increases in these properties were observed above 70 wt % DGEBA content in the reactive blends. SEM studies revealed that the reactive blends show a multiphase system with an increase in the DGEBA content from 50 to 80 wt % as the mixing of the two phases increased. The reactive blend Ep₈₀Ca₂₀, with 80 wt % DGEBA content, resembles a single‐phase system because of better mixing of the two phases; as a result, this reactive blend showed the highest mechanical and electrical properties. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 537–549, 2005     

In‐situ reinforcement of PBT/ABS blends with liquid crystalline polymer

Ternary in‐situ poly(butylene terephthalate) (PBT)/poly(acrylonitrile‐butadienestyrene) (ABS)/liquid crystalline polymer(LCP) blends were prepared by injection molding. The LCP used was a versatile Vectra A950, and the matrix material was PBT/ABS 60/40 by weight. Maleic anhydride (MA) copolymer and solid epoxy resin (bisphenol type‐A) were used as compatibilizers for these blends. The tensile, dynamic mechanical, impact, morphology and thermal properties of the blends were studied. Tensile tests showed that the tensile stregth of PBT/ABS/LCP blend in the longitudinal direction increased markedly with increasing LCP content. However, it decreased sharply with increasing LCP content up to 5 wt%; thereafter it decreased slowly with increasing LCP content in the transverse direction. The modulus of this blend in the longitudinal direction appeared to increase considerably with increasing LCP content, whereas the incorporation of LCP into PBT/ABS blends had little effect on the modulus in the transverse direction. The impact tests revealed that the Izod impact strength of the blends in longitudinal direction decreased with increasing LCP content up to 10 wt%; thereafter it increased slowly with increasing LCP. Dynamic mechanical analyses (DMA) and thermogravimetric measurements showed that the heat resistance and heat stability of the blends tended to increase with increasing LCP content. SEM observation, DMA, and tensile measurement indicated that the additions of epoxy and MA copolymer to PBT/ABS matrix appeared to enhance the compatibility between PBT/ABS and LCP.     

Mechanical properties and morphology of liquid crystalline copolyester-amide and amorphous polyamide blends

Blends of an amorphous polyamide (PA) and a liquid crystalline copolyesteramide (LCP), poly(naphthoate-aminophenoterephthalate) were prepared in a twin-screw extruder. Specimens for mechanical testing were prepared by injection molding. Morphological, thermal, mechanical, and rheological properties were investigated by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-ray diffractometry, capillary rheometry, and a tensile tester, respectively. The tensile mechanical behavior of the LCP/PA blends was found to be affected by their compositions and specimen thickness. Tensile testing revealed that the tensile mechanical behavior of the LCP/PA blends was very similar to that of polymeric composite and the tensile strength of the LCP/PA (50/50) blend was approximately two times of the value of PA homopolymer and exceeded that of pure LCP. The morphology of the LCP/PA blends was also found to be affected by their compositions. SEM studies revealed that the liquid crystalline polymer (LCP) formed finely dispersed spherical domains in the PA matrix and the inclusions were deformed into fibrils from the spherical droplets with increasing LCP content. It has been found that droplet and fiber formations lead to low and high strength material, respectively. In particular, at specific LCP content (50 wt%), the tensile strength of the LCP/PA blend exceeded that of pure LCP. The improvement in tensile properties is likely due to the reinforcement of the PA matrix by the fibrous LCP phase as observed by SEM. A distinct shell-core morphology was found to develop in the injection molded samples of these blends. This is believed to have a synergistic effect on the tensile properties of the LCP/PA blends. The rheological behavior of the LCP/PA blends was found to be very different from that of the parent polymers and significant viscosity reductions were observed for the LCP/PA (50/50) blend. Based upon DSC, these blends have shown to be incompatible in the entire range of concentrations.     

In situ compatibilization of PEN/LCP blends by ultrasonic extrusion

In situ compatibilization of immiscible blends of PEN and thermotropic LCP was achieved by the ultrasonically‐aided extrusion process. Ultrasonically‐treated PEN underwent degradation, leading to a decrease of its viscosity. Viscosity of LCP was unaffected by ultrasonic treatment. Because of reduced viscosity ratio of PEN to LCP at high amplitude of ultrasonic treatment, larger LCP domains were observed in molding of the blends. LCP acted as a nucleating agent, promoting higher crystallinity in PEN/LCP blends. Ultrasonically‐induced copolymer formation was detected by MALDI‐TOF mass spectrometry in the blends. Ultrasonic treatment of 90/10 PEN/LCP blends improved interfacial adhesion in fibers spun at intermediate draw down ratios (DDR), improving their ductility. The lack of improvement in the mechanical properties of fibers spun at high DDR after ultrasonic treatment was attributed to the disturbance of interfacial copolymer by high elongation stresses. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

Improved mechanical properties of NR/EPDM blends by controlling the migration of curative and filler via reactive processing technique

Simple blending of natural rubber/ethylene–propylene–diene rubber (NR/EPDM) generally results in inferior mechanical properties because of curative migration and their differences for filler affinity. In this work, the 70/30 and 50/50 NR/EPDM blends prepared by reactive processing techniques were investigated and compared with the simple, nonreactive blends. The reactive blend compounds were prepared by preheating EPDM, containing all curatives to a predetermined time related to their scorch time prior to blending with NR. For the 70/30 gum blends, four types of accelerators were studied: 2,2‐mercaptobenzothiazole (MBT), 2,2‐dithiobis‐ (benzothiazole) (MBTS), N‐cyclohexyl‐2‐benzothiazolesulfenamide (CBS), and N‐tert‐butyl‐2‐benzothiazolesulfenamide (TBBS). When compared with the simple blends, the reactive blends cured with CBS and MBTS showed a clearly improved tensile strength whereas the increase of tensile strength in the blends cured with TBBS and MBT was marginal. However, a dramatic improvement of ultimate tensile properties in the reactive 50/50 NR/EPDM blends cured with TBBS was observed when compared with the simple blend. For the N‐550‐filled blends at the blend ratios of 70/30 and 50/50, the reactive‐filled blends prepared under the optimized preheating times demonstrated superior tensile strength and elongation at break over the simple blends. The improved crosslink and/or filler distribution between the two rubber phases in the reactive blends accounts for such improvement in their mechanical properties. This is shown in the scanning electron micrographs of the tensile fractured surfaces of the reactive blends, which indicate a more homogeneous blend. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Structural,rheological, and mechanical properties of ternary blends of PEN,PET, and liquid crystalline polymer

Structural, rheological, and mechanical properties of ternary blends of a liquid crystalline copolyester (LCP) composed of p-hydroxybenzoic acid and 2,6-hydroxynaphthoic acid, poly(ehtylene naphthalate)(PEN), and poly(ethylene terephtalate) (PET) were investigated using capillary rheometry, tensile testing, scanning electron microscopy, and X-ray diffraction. Viscosity-shear rate behavior of the ternary blends is very similar to that of pure polymers and their binary blends. The activation energy of flows of the ternary blends was smaller than those of PEN and PET. Tensile modulus and strength of extruded strands of the blends increased with increasing LCP content. The extruded strands of the blends consist of a crystalline and oriented LCP phase and an amorphous and unoriented PEN/PET blended phase. Tensile mechanical properties and structures of the ternary blends were discussed.     

Mechanical,morphological, and thermal properties of poly(ethylene 2,6-naphthalate) and copolyester LCP blends

Binary blends of a liquid crystalline polymer (LCP) and poly(ethylene 2,6-naphthalate) (PEN) were melt blended and injection molded. The mechanical properties were studied as a function of LCP content. Both the ultimate tensile strength and Young's modulus are higher than the theoretical values predicted by the rule of mixtures and they display a synergistic behavior at 70 wt % LCP content. However, the tensile strength decreases with LCP content and Young's modulus remained unchanged at lower LCP contents (10 to 30 wt %). The poor mechanical property is attributed to the immiscibility between PEN and LCP and the fibrillation behavior of LCP as revealed by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) results. However, LCP and PEN are found to be partially miscible at higher LCP content, ascertained by DSC and dynamic mechanical analysis (DMA). This is attributed to the transesterification reaction between PEN and PET moiety in the LCP molecules. SEM micrographs reveal a skin/core morphology in the tensile bars, that is, the LCP is better oriented in the skin than in the core region. At lower LCP content, the dispersed LCP phase is spherical in the core and ellipsoidal in the skin, with long axes oriented in the flow direction. DSC studies show that the crystallization rate is significantly enhanced by the presence of LCP up to 50 wt %, where the LCP acts as a nucleating agent for PEN crystallization. The melting temperature decreases with LCP content, probably as a result of imperfect crystals formed in the presence of LCP heterogeneous nucleating centers and the increasing miscibility between LCP and PEN. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 477–488, 2001     

Injection molding of PC/PBT/LCP ternary in situ composite

A liquid crystalline polymer (LCP), Vectra B950, reinforced polycarbonate (PC) 60 wt%/polybutylene terephthalate (PBT) 40 wt% blend was studied using the injection molding process. Morphology and mechanical properties of ternary in situ LCP composites were investigated and compared with binary polycarbonate/Vectra B950 LCP composites. Good in situ fibrillation of LCP was observed in the direct injection-molded LCP composites. Preliminary results of this work indicate that addition of PBT improves skin-core distribution of LCP microfibrils in the matrix and also enhances adhesion between the matrix and Vectra B950, which contains terephthalic acid. The PC/PBT/LCP ternary system also exhibits lower viscosity than the PC/PBT blend and pure LCP. In a ternary system with 30 wt% of Vectra B950, tensile modulus and strength increase approximately threefold and twofold, respectively. The rule of mixtures (ROM) for continuous reinforcement can accurately represent the strengthening effects for the ternary LCP in situ composites. Generally, LCP reduces the ductility and impact strength of the thermoplastic blends; however, the relative loss is less in the ternary system than in the binary system.     

Rheological and mechanical properties of polycarbonate–liquid-crystalline polymer blends with controlled chemical reactions

Chemical reactions can occur during the melt blending of polymers containing an ester group because ester groups are usually unstable at high temperatures; this instability generally deteriorates the mechanical properties of blends. Here, effects of chemical reactions on the rheological and mechanical properties of polycarbonate (PC)/liquid-crystalline polymer (LCP) blends are carefully investigated to determine a method for minimizing such undesirable impacts. For comparison, a physical blend, in which chemical reactions were minimized, was prepared at 300 °C in a twin-screw extruder. Both shear viscosity and complex viscosities of reactive blends were lower than those of physical blends, being almost proportional to [M_w ]^3.4 as a result of depolymerization and transesterification. Because of the enhanced miscibility, the tensile modulus of reactive blends increased compared with that of physical blend, according to the increase in the degree of incorporation (DI). It was also possible to increase tensile modulus if triester was added to the reactive blends. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2799–2807, 2001     

Influences of dicumyl peroxide on morphology and mechanical properties of polypropylene/poly(styrene‐b‐butadiene‐b‐styrene) blends via vane‐extruder

Polypropylene (PP) and poly(styrene‐b‐butadiene‐b‐styrene) block copolymer (SBS) were melt‐blended in the presence of initiator system. Dicumyl peroxide (DCP)/Triallyl isocyanurate (TAIC) via self‐deigned VE, aiming at in situ reactive compatibilization of toughed PP/SBS blend. The reactivity, morphology and mechanical properties of PP/SBS/DCP/TAIC blends were studied. Online torque detection was conducted to monitor changes in viscosities of reactive compatibilized blends, which could give proof of the interfacial grafted reaction induced by DCP/TAIC system. The effect of reactive compatibilization on the dispersed particles sizes and interfacial adhesion was studied by scanning electron microscopy. Analysis on mechanical performance revealed the impact strength improved after treated by initiator system, moreover, the impact‐fractured surface observation showed, the failure mode changed from debonding mechanism of neat 50PP/50SBS blend to plastic deformation mechanism of blend containing 3.0 phr initiator system. With improved interfacial adhesion, compatibilized blends not only were toughened but also exhibited enhanced tensile strength and thermal stability. Dynamic mechanical analysis showed a reduction of between PP phase and the PB segments in SBS phase, indicating reactive compatibilization of the blend was achieved. In the final part, a brief discussion was given about the dominant effects from chain scission of PP matrix to intergrafting reactions of PP and SBS, under different content of DCP/TAIC initiator system. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41543.     

原位增强聚丙烯/液晶复合材料结构与性能研究

利用自制的复合拉伸挤出成型口模对材料进行拉伸挤出,并探讨添加不同含量的液晶材料对聚丙烯（PP）结构与性能的影响。结果表明,少量的液晶聚合物在PP基体中形成了纤维结构,当液晶的添加量为10份时,复合材料的力学性能最大可提高25.2%,热变形温度提高21.1℃;适量的液晶的加入有利于改善PP材料的流动性能,有利于PP基体结晶度的改善。     

Properties of uncompatibilized and compatibilized poly(butylene terephthalate)–LLDPE blends

In this work, blends of poly(butylene terephthalate) (PBT) and linear low‐density polyethylene (LLDPE) were prepared. LLDPE was used as an impact modifier. Since the system was found to be incompatible, compatibilization was sought for by the addition of the following two types of functionalized polyethylene: ethylene vinylacetate copolymer (EVA) and maleic anhydride‐grafted EVA copolymer (EVA‐g‐MAH). The effects of the compatibilizers on the rheological and mechanical properties of the blends have been also quantitatively investigated. The impact strength of the PBT–LLDPE binary blends slightly increased at a lower concentration of LLDPE but increased remarkably above a concentration of 60 wt % of LLDPE. The morphology of the blends showed that the LLDPE particles had dispersed in the PBT matrix below 40 wt % of LLDPE, while, at 60 wt % of LLDPE, a co‐continuous morphology was obtained, which could explain the increase of the impact strength of the blend. Generally, the mechanical strength was decreased by adding LLDPE to PBT. Addition of EVA or EVA‐g‐MAH as a compatibilizer to PBT–LLDPE (70/30) blend considerably improved the impact strength of the blend without significantly sacrificing the tensile and the flexural strength. More improvement in those mechanical properties was observed in the case of the EVA‐g‐MAH system than for the EVA system. A larger viscosity increase was also observed in the case of the EVA‐g‐MAH than EVA. This may be due to interaction of the EVA‐g‐MAH with PBT. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 989–997, 1999     

Polymer blends of poly(ethylene‐2,6‐naphthalate) with polystyrene compatibilized by styrene‐glycidyl methacrylate copolymers. I. Rheology,morphology, and mechanical properties

The compatibilization of blends of poly(ethylene‐2,6‐naphthalate) (PEN) with polystyrene (PS), through the styrene‐glycidyl methacrylate copolymers (SG) containing various glycidyl methacrylate (GMA) contents, was investigated in this study. SG copolymers are able to react with PEN terminal groups during melt blending, resulting in the formation of desirable SG‐g‐PEN copolymers in the blend. These in situ formed copolymers tend to reside along the interface preferentially as the result of interfacial reaction and thus function as effective compatibilizers in PEN/PS blends. The compatibilized blends exhibit higher viscosity, finer phase domain, and improved mechanical properties. It is found that the degree of grafting of the in situ formed SG‐g‐PEN copolymer has to be considered as well. In blends compatibilized with the SG copolymer containing higher GMA content, heavily grafted copolymers would be produced. The length of the styrene segment in these heavily grafted copolymers would be too short to penetrate deep enough into the PS phase to form effective entanglements, resulting in the lower compatibilization efficiency in PEN/PS blends. Consequently, the in situ formation of SG‐g‐PEN copolymers with an optimal degree of grafting is the key to achieving the best performance for the eventually produced PEN/PS blends through SG copolymers. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 967–975, 2003     

In situ compatibilized SAN/LCP blends through reactive copolymers

Styrene–acrylonitrile–glycidyl methacrylate (SAG) copolymers with various contents of glycidyl methacrylate (GMA) were used to compatibilize the incompatible blends of styrene–acrylonitrile (SAN) and a liquid crystalline polymer (LCP). These SAG copolymers contain reactive glycidyl groups that are able to react with the carboxylic acid and/or hydroxyl end groups of the LCP to form the SAG‐g‐LCP copolymers during melt processing. The in situ–formed graft copolymers tend to reside along the interface to reduce the interfacial tension and to increase the interface adhesion. The morphologies of the SAN/LCP blends were examined by using scanning electron microscopy (SEM), where the compatibilized SAN/LCP blends were observed with greater numbers and finer fibrils than those of the corresponding uncompatibilized blends. The mechanical properties of the blends increased after compatibilization. The presence of a small amount (200 ppm) of ethyl triphenylphosphonium bromide (ETPB) catalyst further promotes the graft reaction and improves the compatibilization. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 3321–3332, 2001     

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