Polyoxymethylene/ethylene butylacrylate copolymer/ethylene‐methyl acrylate‐glycidyl methacrylate ternary blends

Blends of compatibilized polyoxymethylene (POM)/ethylene butylacrylate copolymer (EBA)/ethylene‐methyl acrylate‐glycidyl methacrylate copolymer (EMA‐GMA) and uncompatibilized POM/EBA were investigated. The notched impact strength of the compatibilized blends was higher than that of their uncompatibilized counterparts. The toughness of the POM blends was improved obviously with relatively low loading of EBA. Fourier transform infrared spectroscopy (FTIR) spectra of EMA‐GMA, pure POM, and POM/EBA/EMA‐GMA blends indicated that epoxy groups of EMA‐GMA reacted with terminal hydroxyl groups of POM molecular chains. The glass‐transition temperature (T_g) values of the POM matrix and the EBA phase were observed shifted to each other in the presence of EMA‐GMA compatibilizer indicating that the compatibilized blends had better compatibility than their uncompatibilized counterparts. With the addition of EBA to POM, both the compatibilized and uncompatibilized blends showed higher onset degradation temperature (T_d) than that of pure POM and the T_d values of the compatibilized blends were higher than those of their uncompatibilized counterparts. The scanning electron microscopy showed better EBA particles distribution state in the compatibilized system than in the uncompatibilized one. The compatibilized blend with an obvious rougher impact fracture surface indicated the ductile fracture mode. POLYM. ENG. SCI., 58:1127–1134, 2018. © 2017 Society of Plastics Engineers     

Properties of waste‐poly(ethylene terephthalate)/acrylonitrile butadiene styrene blends compatibilized with maleated acrylonitrile butadiene styrene

Waste poly(ethylene terephthalate) (W‐PET)/acrylonitrile‐butadiene‐styrene (ABS) blends were prepared with a variety of compositions at several rotor speeds in an internal mixer, replacing ABS with different maleated ABS (ABS‐g‐MA) samples in compatibilized blends. A Box–Behnken model for three variables, with three levels, was chosen for the experimental design. ABS‐g‐MA‐based samples exhibited finer particles with a more uniform particle size distribution than ABS‐based ones, as a consequence of the compatibilizing process. Rheological results implied a greater elastic nature for compatibilized blends which increased in the presence of more ABS content; the same trend was observed for complex viscosity. With increasing ABS‐g‐MA or MA concentration, more shear thinning behavior was observed similar to that of ABS; whereas the uncompatibilized blends showed Newtonian behavior like that of W‐PET. The observed shifting in T_gW‐PET and T_gABS obtained from dynamic mechanical thermal analysis confirmed the good compatibility in W‐PET/ABS‐g‐MA blends in contrast with that in ordinary W‐PET/ABS blends. The mechanical properties were measured and modeled versus the various factors considered in a response surface methodology. The experimental data found a good fit with the obtained equation models. The mechanical properties of the compatibilized blends showed a large positive deviation from the mixing rule, while the uncompatibilized samples had lower properties, even compared to those predicted by the mixing rule. J. VINYL ADDIT. TECHNOL., 2010. © 2010 Society of Plastics Engineers     

Artificial weathering effect on the structure and properties of polypropylene/polyamide‐6 blends compatibilized with PP‐g‐MA

The degradation of uncompatibilized and compatibilized PP/PA‐6 (70/30 wt %) with PP‐g‐MA under accelerated UV light was investigated using Fourier Transform Infrared Spectroscopy (FTIR) spectroscopy, melt flow index (MFI) tester, tensile test, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). FTIR analysis of the structure of the compatibilized and uncompatibilized blends after exposure to UV light showed the formation of photoproducts corresponding to both components. The MFI and mechanical results obtained revealed that photooxidation started primarily in PA‐6 rather than PP. In addition, the uncompatibilized blends exhibited a higher degradation rate compared to neat polymers for long exposure time, and the addition of PP‐g‐MA increased slightly their ageing rate in accordance with TGA data. Further, DSC analysis showed an increase in the crystallinity index and a decrease in the melting temperature of PP and PA‐6 after UV exposure either as neat polymers or as blend components. SEM micrographs of the cryo‐fractured surfaces of the samples illustrated the formation of cracks and fractures after UV irradiation. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41722.     

Effects of extensional flow on properties of polyamide‐66/poly(2,6‐dimethyl‐1,4‐phenylene oxide) blends: A study of morphology,mechanical properties,and rheology

In this study, polyamide‐66/poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PA66/PPO) blends with high viscosity ratio were processed by a self‐designed triangle‐arrayed triple‐screw extruder (TTSE, which simulates extensional flow) and a commercial twin‐screw extruder (TSE), respectively. Furthermore, in order to improve the mechanical properties of the immiscible PA66/PPO blends, PPO‐grafted maleic anhydride (PPO‐g‐MA) and styrene–ethylene–butylene–styrene (SEBS) block copolymer were used. The mechanical properties, phase morphology, and rheological properties of both binary PA66/PPO blends and toughened PA66/PPO/PPO‐g‐MA blends were comprehensively investigated to compare the above mentioned two processing method. Samples processed with TTSE exhibited better mechanical properties than the TSE‐processed blends. The morphologies of the blends were examined by scanning electron microscopy, exhibiting smaller particles sizes and narrower particle size distributions, which were attributed to the significant effects of extensional flow in TTSE. The toughening mechanism of compatibilized blends was investigated through morphology analysis, dynamic mechanical, and rhelogical analysis. Thus, TTSE with an extensional effect was proved to be efficient in the blending of high viscosity ratio polymers. POLYM. ENG. SCI., 57:1090–1098, 2017. © 2016 Society of Plastics Engineers     

Effect of poly [styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene] (SEBS) and maleic anhydride‐grafted SEBS triblock copolymers in immiscible blends of (polyamide‐6)/polycarbonate: Morphology‐mechanical properties relationships

The effects of using maleated poly[styrene‐b‐(ethylene‐co‐butylene)‐b‐styrene] triblock copolymer (SEBS‐g‐MAH) and unmodified SEBS (unSEBS) on the phase morphology and mechanical properties of immiscible polymer blends of polyamide‐6 (PA‐6) and polycarbonate (PC) are investigated. Different binary, ternary, and quaternary blends were prepared by using a Brabender® co‐rotating twin‐screw extruder. The weight ratio of unSEBS to SEBS‐g‐MAH was changed to probe the phase morphology and mechanical properties. The results revealed that the mechanical properties of (PA‐6)/PC/(unSEBS/SEBS‐g‐MAH) blends were considerably governed by the unSEBS to SEBS‐g‐MAH weight ratio. Morphological investigation based on the spreading coefficient concept confirmed the results of scanning electron microscopy, indicating encapsulation of unSEBS domains around the PC core‐forming component in the presence of reactive SEBS‐g‐MAH precursor. Moreover, larger unSEBS‐PC composite droplets appeared throughout PA‐6 matrix upon increasing the ratio of unSEBS to SEBS‐g‐MAH, until reaching a maximum value. In the case of the (PA‐6)/PC blend compatibilized with a 50/50 combination of unSEBS and SEBS‐g‐MAH, the highest mechanical properties, i.e., tensile strength, impact resistance, and strain at break, were achieved owing to compatibilizing effect of virgin and maleated SEBS constituents. J. VINYL ADDIT. TECHNOL., 21:245–252, 2015. © 2014 Society of Plastics Engineers     

Melt rheological properties of polypropylene–polyamide6 blends compatibilized with maleic anhydride‐grafted polypropylene

The melt rheological properties of binary uncompatibilized polypropylene–polyamide6 (PP–PA6) blends and ternary blends compatibilized with maleic anhydride‐grafted PP (PP–PP‐g‐MAH–PA6) were studied using a capillary rheometer. The experimental shear viscosities of blends were compared with those calculated from Utracki's relation. The deviation value δ between these two series of data was obtained. In binary PP–PA6 blends, when the compatibility between PP and PA6 was poor, the deformation recovery of dispersed PA6 particles played the dominant role during the capillary flow, the experimental values were smaller than those calculated, and δ was negative. The higher the dispersed phase content, the more deformed the droplets were and the lower the apparent shear viscosity. Also, the absolute value of δ increased with the dispersed phase composition. In ternary PP–PP‐g‐MAH–PA6 systems, when the compatibility between PP and PA6 was enhanced by PP‐g‐MAH, the elongation and break‐up of the dispersed particles played the dominant role, and the experimental values were higher than calculated. It was observed that the higher the dispersion of the PA6 phase, the higher the δ values of the ternary blends and the larger the positive deviation. Unlike uncompatibilized blends, under high shear stress with higher dispersed phase content, the PP‐g‐PA6 copolymer in compatibilized blends was pulled out from the interface and formed independent micelles in the matrix, which resulted in reduced total apparent shear viscosity. The δ value decreased with increasing shear stress. Copyright © 2006 Society of Chemical Industry     

Rheology and sheet extrusion of Novatein thermoplastic protein/polybutylene adipate-co-terephthalate blends

Novatein is a thermoplastic polymer made from blood meal proteins, but it has rheological properties very different from commodity thermoplastics. Capillary rheometry revealed an apparent time dependent shear viscosity for Novatein, evident from a decreasing pressure drop over time, measured at constant shear rate. However, blending with polybutylene adipate-co-terephthalate (PBAT) reduced the time dependence for uncompatibilized blends and virtually eliminated time dependence for compatibilized blends containing 30 wt % PBAT. Novatein's extensional viscosity is three orders of magnitude more than its shear viscosity and explained the difficulty in sheet extrusion. In contrast, 30% compatibilized blends had an extensional viscosity similar to neat PBAT and was also the only blend that could be successfully sheet extruded. Although uncompatibilized blends at the same or lower PBAT content also had a lower extensional viscosity, they could not be sheet extruded and the difference was the 30% compatibilized blends had a fine PBAT phase structure (co-continuous in this case), which was sufficiently adhered to the Novatein phase. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47977.     

Compatibilization of polypropylene/nylon 6 blends with a polypropylene solid‐phase graft

The compatibilization of polypropylene (PP)/nylon 6 (PA6) blends with a new PP solid‐phase graft copolymer (gPP) was systematically studied. gPP improved the compatibility of PP/PA6 blends efficiently. Because of the reaction between the reactive groups of gPP and the NH₂ end groups of PA6, a PP‐g‐PA6 copolymer was formed as a compatibilizer in the vicinity of the interfaces during the melting extrusion of gPP and PA6. The tensile strength and impact strength of the compatibilized PP/PA6 blends obviously increased in comparison with those of the PP/PA6 mechanical blends, and the amount of gPP and the content of the third monomer during the preparation of gPP affected the mechanical properties of the compatibilized blends. Scanning electron microscopy and transmission electron microscopy indicated that the particle sizes of the dispersed phases of the compatibilized PP/PA6 blends became smaller and that the interfaces became more indistinct in comparison with the mechanical blends. The microcrystal size of PA6 and the crystallinity of the two components of the PP/PA6 blends decreased after compatibilization with gPP. The compatibilized PP/PA6 blends possessed higher pseudoplasticity, melt viscosity, and flow activation energy. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 420–427, 2004     

Morphology and mechanical properties of polyamide‐6/K resin blends

Mechanical properties and morphological studies of compatibilized blends of polyamide‐6 (PA‐6)/K resin grafted with maleic anhydride (K‐g‐MAH) and PA‐6/K resin/K‐g‐MAH were investigated as functions of K resin/K‐g‐MAH and dispersed phase K resin concentrations, and all the blends were prepared using twin screw extruder followed by injection molding. Scanning electron microscopy (SEM) were used to assess the fracture surface morphology and the dispersion of the K resin in PA‐6 continuous phase, the results showing extensive deformation in presence of K‐g‐MAH, whereas, uncompatibilized PA‐6/K resin blends show dislodging of K resin domains from the PA‐6 matrix. Dynamic mechanical thermal analysis (DMTA) test reveals the partially miscibility of PA‐6 with K‐g‐MAH, and differential scanning calorimetry (DSC) results further identified that the introduction of K‐g‐MAH greatly improved the miscibility between PA‐6 and K resin. The mechanical properties of PA‐6/K resin blends and K‐g‐MAH were studied through bending, tensile, and impact properties. The Izod notch impact strength of PA‐6/K‐g‐MAH blends increase with the addition of K‐g‐MAH, when the K‐g‐MAH content adds up to 20 wt %, the impact strength is as more than 6.2 times as pure PA‐6, and accompanied with small decrease in the tensile and bending strength less than 12.9% and 17.5%, respectively. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Toughening and compatibilization of polypropylene/polyamide‐6 blends with a maleated–grafted ethylene‐co‐vinyl acetate

In this article, maleated–grafted ethylene‐co‐vinyl acetate (EVA‐g‐MA) was used as the interfacial modifier for polypropylene/polyamide‐6 (PP/PA6) blends, and effects of its concentration on the mechanical properties and the morphology of blends were investigated. It was found that the addition of EVA‐g‐MA improved the compatibility between PP and PA6 and resulted in a finer dispersion of dispersed PA6 phase. In comparison with uncompatibilized PP/PA6 blend, a significant reduction in the size of dispersed PA6 domain was observed. Toluene‐etched micrographs confirmed the formation of interfacial copolymers. Mechanical measurement revealed that the addition of EVA‐g‐MA markedly improved the impact toughness of PP/PA6 blend. Fractograph micrographs revealed that matrix shear yielding began to occur when EVA‐g‐MA concentration was increased upto 18 wt %. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 99:3300–3307, 2006     

Poly(ethylene‐graft‐ethylene oxide) (PE‐PEO) and poly(ethylene‐co‐acrylic acid) (PEAA) as compatibilizers in blends of LDPE and polyamide‐6

In a blend of two immiscible polymers a controlled morphology can be obtained by adding a block or graft copolymer as compatibilizer. In the present work blends of low‐density polyethylene (PE) and polyamide‐6 (PA‐6) were prepared by melt mixing the polymers in a co‐rotating, intermeshing twin‐screw extruder. Poly(ethylene‐graft‐polyethylene oxide) (PE‐PEO), synthesized from poly(ethylene‐co‐acrylic acid) (PEAA) (backbone) and poly(ethylene oxide) monomethyl ether (MPEO) (grafts), was added as compatibilizer. As a comparison, the unmodified backbone polymer, PEAA, was used. The morphology of the blends was studied by scanning electron microscopy (SEM). Melting and crystallization behavior of the blends was investigated by differential scanning calorimetry (DSC) and mechanical properties by tensile testing. The compatibilizing mechanisms were different for the two copolymers, and generated two different blend morphologies. Addition of PE‐PEO gave a material with small, well‐dispersed PA‐spheres having good adhesion to the PE matrix, whereas PEAA generated a morphology characterized by small PA‐spheres agglomerated to larger structures. Both compatibilized PE/PA blends had much improved mechanical properties compared with the uncompatibilized blend, with elongation at break (ε_b) increasing up to 200%. Addition of compatibilizer to the PE/PA blends stabilized the morphology towards coalescence and significantly reduced the size of the dispersed phase domains, from an average diameter of 20 μm in the unmodified PE/PA blend to approximately 1 μm in the compatibilized blends. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 2416–2424, 2000     

Thermal behavior and morphology of polyamide 6 based multicomponent blends

The thermal behavior and morphology of multicomponent blends based on PA6, polyamide 6 (PA6)/styrene–acrylonitirle copolymer (SAN), PA6/acrylonitrile–butadiene–styrene terpolymer (ABS), and their compatibilized blends with styrene–acrylonitrile–maleic anhydride copolymer (SANMA) were studied using DSC and SEM. The blends were prepared in a twin‐screw extruder under similar processing conditions, keeping the PA6 content fixed at 50 wt %. It was found that, in all the blends, the second component had a nucleating effect and improved the overall degree and rate of crystallization of PA6, whereas addition of a compatibilizer slightly diminished these effects and resulted in significant changes in the blend morphology. The nucleating effect and consequent changes in the crystallization behavior was attributed to the presence of SAN, which is a common component in all the blends. The T_g of PA6 in the blends with a cocontinuous morphology, due to the connectivity between the phases, is higher than in the blends with a disperse‐type morphology. The compatibilized blends have a lower crystallization rate and nucleation ability with a cocontinuous morphology, whereas the uncompatibilized blends have a higher crystallization rate with a higher nucleation ability and a disperse and/or a coarse cocontinuous morphology. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2753–2759, 2002     

Melt rheology and properties of compatibilized recycled poly(ethylene terephthalate)/(styrene‐ethylene‐ethylene‐propylene‐styrene) block copolymer blends

Blends of recycled poly(ethylene terephthalate) (R‐PET) and (styrene‐ethylene‐ethylene‐propylene‐styrene) block copolymer (SEEPS) compatibilized with (maleic anhydride)‐grafted‐styrene‐ethylene‐butylene‐styrene (SEBS‐g‐MAH) were prepared by melt blending. The compatibilizing effects of SEBS‐g‐MAH were investigated systematically by study of the morphology, linear viscoelastic behavior, and thermal and mechanical properties of the blends. The results show that there is good agreement between the results obtained by rheological measurement and morphological analysis. The rheological test shows that the melt elasticity and melt strength of the blends increase with the addition of SEBS‐g‐MAH. The Cole‐Cole plots and van Gurp‐Palmen plots confirm the compatibilizing effect of SEBS‐g‐MAH. However, the Palierne model fails to predict the linear viscoelastic properties of the blends. The morphology observation shows that all blends exhibit a droplet‐matrix morphology. In addition, the SEEPS particle size in the (R‐PET)/SEEPS blends is significantly decreased and dispersed uniformly by the addition of SEBS‐g‐MAH. Differential scanning calorimeter analysis shows that the crystallization behavior of R‐PET is restricted by the incorporation of SEEPS, whereas the addition of SEBS‐g‐MAH improves the crystallization behavior of R‐PET compared with that of uncompatibilized (R‐PET)/SEEPS blends. The Charpy impact strength of the blends shows the highest value at SEBS‐g‐MAH content of 10%, which is about 210% higher than that of pure R‐PET. J. VINYL ADDIT. TECHNOL., 22:342–349, 2016. © 2014 Society of Plastics Engineers     

Effect of compatibilization on the properties of HIPS/PA1010 blends

Blends consisting of high‐impact polystyrene (HIPS) as the matrix and polyamide 1010 (PA1010) as the dispersed phase were prepared by mixing. The grafting copolymers of HIPS and maleic anhydride (MA), the compatibilizer precursors of the blends, were synthesized. The contents of the MA in the grafting copolymers are 4.7 wt % and 1.6 wt %, and were assigned as HAM and LMA, respectively. Different blend morphologies were observed by scanning electron microscopy (SEM); the domain size of the PA1010 dispersed phase in the HIPS matrix of compatibilized blends decreased comparing with that of uncompatibilized blends. For the blend with 25 wt % HIPS‐g‐MA component, the T_c of PA1010 shifts towards lower temperature, from 178 to 83°C. It is found that HIPS‐g‐MA used as the third component has profound effect on the mechanical properties of the resulting blends. This behavior has been attributed to the chemical reaction taking place in situ during the mixing between the two components of PA1010 and HIPS‐g‐MA. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 799–806, 2000     

Properties of ethylene–propylene copolymer/PA-1010 blends using ethylene–propylene copolymer-graft-acrylic acid as a compatibilizing agent

The modification of ethylene–propylene copolymer (EP) has been accomplished by radical initiators. The resulting EP-graft-acrylic acid (EP-g-AA) has been used to obtain ternary PA/EP/EP-g-AA blends by melt mixing. Different blend morphologies were observed by scanning electron microscopy: the domain size of the EP-dispersed phase in the polyamide 1010 matrix of compatibilized blends decreased compared with that of uncompatibilized blends. It is found that EP-g-AA used as the third component has a profound effect on the mechanical properties of the resulting blends. This behavior has been attributed to serious chemical interactions taking place between the two components. Thermal analysis shows that some thermal properties of PA in compatibilized PA/EP/EP-g-AA changed because of chemical reactions taken place during the blending process. Wide angle x-ray diffraction measurements also confirmed this result. © 1996 John Wiley & Sons, Inc.     

Gasoline permeation behavior and mechanical properties of polyamide 6/nanoclay,polyamide 6/PE‐g‐maleic anhydride blend,and polyamide 6/PE‐g‐maleic anhydride/clay nanocomposite

In this article, polyamide 6 (PA6)/clay nanocomposites, PA6/polyethylene grafted maleic anhydride (PE‐g‐MA) blends, and PA6/PE‐g‐MA/clay nanocomposites were prepared and their gasoline permeation behavior and some mechanical properties were investigated. In PA6/clay nanocomposites, cloisite 30B was used as nanoparticles, with weight percentages of 1, 3, and 5. The blends of PA6/PE‐g‐MA were prepared with PE‐g‐MA weight percents of 10, 20, and 30. All samples were prepared via melt mixing technique using a twin screw extruder. The results showed that the lowest gasoline permeation occurred when using 3 wt % of nanoclay in PA6/clay nanocomposites, and 10 wt % of PE‐g‐MA in PA6/PE‐g‐MA blends. Therefore, a sample of PA6/PE‐g‐MA/clay nanocomposite containing 3 wt % of nanoclay and 10 wt % of PE‐g‐MA was prepared and its gasoline permeation behavior was investigated. The results showed that the permeation amount of PA6/PE‐g‐MA/nanoclay was 0.41 g m^?2 day^?1, while this value was 0.46 g m^?2 day^?1 for both of PA6/3wt % clay nanocomposite and PA6/10 wt % PE‐g‐MA blend. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40150.     

Morphology,thermal behavior,and mechanical properties of PA6/UHMWPE blends with HDPE‐g‐MAH as a compatibilizing agent

A functionalized high‐density polyethylene (HDPE) with maleic anhydride (MAH) was prepared using a reactive extruding method. This copolymer was used as a compatibilizer of blends of polyamide 6 (PA6) and ultrahigh molecular weight polyethylene (UHMWPE). Morphologies were examined by a scanning electron microscope. It was found that the dimension of UHMWPE and HDPE domains in the PA6 matrix decreased dramatically, compared with that of the uncompatibilized blending system. The size of the UHMWPE domains was reduced from 35 μm (PA6/UHMWPE, 80/20) to less than 4 μm (PA6/UHMWPE/HDPE‐g‐MAH, 80/20/20). The tensile strength and Izod impact strength of PA6/UHMWPE/HDPE‐g‐MAH (80/20/20) were 1.5 and 1.6 times as high as those of PA6/UHMWPE (80/20), respectively. This behavior could be attributed to chemical reactions between the anhydride groups of HDPE‐g‐MAH and the terminal amino groups of PA6 in PA6/UHMWPE/HDPE‐g‐MAH blends. Thermal analysis was performed to confirm that the above chemical reactions took place during the blending process. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 232–238, 2000     

Thermal and flow property–morphology relationship of sugarcane bagasse fiber‐filled polyamide 6 blends

The structure–property relationship of sugarcane bagasse fiber‐filled polyamide 6 blends at different blend compositions has been investigated. Blends were prepared in the composition of wt % PA6/wt % bagasse as follows: 98/2, 95/5, and 90/10 for three fiber length ranges (<100, <250, and <500 μm) using a twin‐screw extruder. Thermal properties were evaluated by measuring the glass transition temperature T_g, enthalpy of fusion ΔH_f, crystallinity X_c and thermogravimetry, TG. Results showed that T_g of the composites changed with change in fiber loading and length. The X_c as well as ΔH_f of the blends reduced to almost half its value for the neat PA6. The thermogravimetric curves TG showed that the thermal stability of the composites was lower than that of the neat PA6. Rheological properties were studied as a function of fiber loading, fiber length, shear rate, and temperature. The viscosity of composites increased with increasing fiber loading and length at low shear rates but decreased below that of neat PA6 at high shear rates. It was also found to be temperature sensitive, and influenced by fiber lengths particularly at higher temperatures. The morphology of the blends was studied using a Leica laser scanning confocal microscopy at two different regions: at the wall, and the core. The micrographs of the blends showed that fibers present in the form of bundles were found at the wall of the extrudates and increased in volume with increase in both length and concentration, at the same temperature and shear stress. In the core region, there is laminar flow, presenting striation morphology, with the omnipresent bundles of fibers dispersed in the matrix. At higher shear rates, the bundles were pushed to the wall. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3744–3754, 2004     

Effects of maleated styrene–(ethylene‐co‐butene)–styrene on the morphology and mechanical and thermal properties of polystyrene/polyamide 1212 blends

Polystyrene (PS)/polyamide 1212 (PA 1212) blends were compatibilized with a maleated triblock copolymer of styrene–(ethylene‐co‐butene)–styrene (SEBS‐g‐MA). Scanning electron microscopy revealed that the addition of SEBS‐g‐MA was beneficial to the dispersion of PA 1212 in the PS matrix because of the reaction between them. The variation of the fraction of SEBS‐g‐MA in the blends allowed the manipulation of the phase structure, which first formed a sheetlike structure and then formed a cocontinuous phase containing PA 1212/SEBS‐g‐MA core–shell morphologies. As a result, the mechanical properties, especially the Charpy notched impact resistance, were significantly improved with the addition of SEBS‐g‐MA. Differential scanning calorimetry (DSC) data indicated that the strong interaction between SEBS‐g‐MA and PA 1212 in the blends retarded the crystallization of PA 1212. The heat distortion temperature of the compatibilized blends was improved in comparison with that of the unmodified blend, probably because of the apparent increase in the glass‐transition temperature with an increasing concentration of SEBS‐g‐MA. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1354–1360, 2005     

Polyamide 6/ethylene‐butylene elastomer blends generated via anionic polymerization of ε‐caprolactam: Phase morphology and dynamic mechanical behavior

This paper reports about the polymerization of ε‐caprolactam monomer in the presence of low molecular weight hydroxyl or isocyanate end‐capped ethylene‐butylene elastomer (EB) elastomers as a new concept for the development of a submicron phase morphology in polyamide 6 (PA6)/EB blends. The phase morphology, viscoelastic behavior, and impact strength of the polymerization‐designed blends are compared to those of similar blends prepared via melt‐extrusion of PA6 homopolymer and EB elastomer. Polyamide 6 and EB elastomer were compatibilized using a premade triblock copolymer PA6‐b‐EB‐b‐PA6 or a pure EB‐b‐PA6 diblock reactively generated during melt‐blending (extrusion‐prepared blends) or built‐up via anionic polymerization of ε‐caprolactam on initiating ? NCO groups attached to EB chain ends (polymerization‐prepared blends). Two compatibilization approaches were considered for the polymerization‐prepared blends: (i) the addition of a premade PA6‐b‐EB‐b‐PA6 triblock copolymer to the ε‐caprolactam monomer containing nonreactive EB? OH elastomer and (ii) generation in situ of a PA6‐b‐EB diblock using EB? NCO precursor on which polyamide 6 blocks are built‐up via anionic polymerization of ε‐caprolactam. The noncompatibilized blends exhibit a coarse phase morphology, either in the extruded or the polymerization prepared blends. Addition of premade triblock copolymer (PA6‐b‐EB‐b‐PA6) to a EB? OH /ε‐caprolactam dispersion led to a fine EB phase (0.14 μm) in the PA6 matrix after ε‐caprolactam polymerization. The average particle size of the in situ reactively compatibilized polymerization‐prepared blend is about 1 μm. The notched Izod impact strength of the blend compatibilized with premade triblock copolymer was much higher than that of the neat PA6, the noncompatibilized, and the in situ reactively compatibilized polymerization blends. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2538–2544, 2004