Evolution of phase morphology and ‘network‐like’ structure of multiwall carbon nanotubes in binary polymer blends during melt‐mixing

Polyamide6 (PA6)/acrylonitrile butadiene styrene copolymer (ABS) blends with unmodified multiwall carbon nanotubes (MWNTs) were prepared via melt‐blending in a conical twin‐screw micro‐compounder with varying melt‐mixing time. To improve the state of dispersion of MWNTs, non‐covalent organic modifiers for MWNTs have been utilized: sodium salt of 6‐amino hexanoic acid (Na‐AHA) and 1‐pyrene‐carboxaldehyde (PyCHO). PA6/ABS blends with MWNTs have shown a phase morphology transition from ‘matrix‐dispersed droplet’ type to ‘co‐continuous’ type as a function of melt‐mixing time with the exception of 40/60 PA6/ABS blend with PyCHO‐modified MWNTs. Non‐isothermal crystallization studies revealed the heterogeneous nucleating action of MWNTs through the presence of double crystallization exothermic peaks (at ～192^°C and >200^°C) while pure PA6 shows bulk crystallization peak at ～192°C. 40/60 and 60/40 (wt/wt) PA6/ABS blends with 5 wt% unmodified MWNTs exhibited electrical conductivity values of ～3.9 × 10^?11 S/cm and ～4.36 × 10^?6 S/cm, respectively. A significant enhancement in electrical conductivity was observed with Na‐AHA and PyCHO‐modified MWNTs (order of ～10^?6 and ～10^?4 S/cm, respectively). POLYM. ENG. SCI., 55:429–442, 2015. © 2014 Society of Plastics Engineers     

The simultaneous addition of styrene maleic anhydride copolymer and multiwall carbon nanotubes during melt‐mixing on the morphology of binary blends of polyamide6 and acrylonitrile butadiene styrene copolymer

The effect of simultaneous addition of multiwall carbon nanotubes (MWNTs) and a reactive compatibilizer (styrene maleic anhydride copolymer, SMA) during melt‐mixing on the phase morphology of 80/20 (wt/wt) PA6/ABS blend has been investigated. Morphological analysis through scanning and transmission electron microscopic analysis revealed finer morphology of the blends in presence of SMA + MWNTs. Fourier transform infrared spectroscopic analysis indicated the formation of imide bonds during melt‐mixing. Non‐isothermal crystallization studies exhibited the presence of a majority faction of MWNTs in the PA6 phase of 80/20 (wt/wt) PA6/ABS blend in presence of SMA + MWNTs. Rheological analysis, dynamic mechanical thermal analysis, and thermogravimetric analysis have demonstrated the compatibilization action of simultaneous addition of a reactive compatibilizer (SMA copolymer) and MWNTs in PA6/ABS blends. An attempt has been made to investigate the role of simultaneous addition of SMA copolymer and MWNTs on the morphology of 80/20 (wt/wt) PA6/ABS blend through various characterization techniques. POLYM. ENG. SCI., 55:457–465, 2015. © 2014 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     

Ternary polymer blends of polyamide 6, polypropylene,and acrylonitrile‐butadiene‐styrene: Influence of multiwalled carbon nanotubes on phase morphology,electrical conductivity,and crystallization

Ternary polymer blends of 80/10/10 (wt/wt/wt) polyamide6 (PA6)/polypropylene (PP)/acrylonitrile‐butadiene‐styrene (ABS), PP/PA6/ABS, and ABS/PP/PA6 were prepared in the presence of multiwalled carbon nanotubes (MWCNTs) by melt‐mixing technique to investigate the influence of MWCNTs on the phase morphology, electrical conductivity, and the crystallization behavior of the PP and PA6 phases in the respective blends. Morphological analysis showed the “core–shell”‐type morphology in 80/10/10 PA6/PP/ABS and 80/10/10 PP/PA6/ABS blends, which was found to be unaltered in the presence of MWCNTs. However, MWCNTs exhibited “compatibilization‐like” action, which was manifested in a reduction of average droplet size of the dispersed phase/s. In contrast, a separately dispersed morphology has been found in the case of 80/10/10 ABS/PP/PA6 blends in which both the phases (PP and PA6) were dispersed separately in the ABS matrix. The electrical percolation threshold for 80/10/10 PA6/PP/ABS and 80/10/10 PP/PA6/ABS ternary polymer blends was found between 3–4 and 2–3 wt% of MWCNTs, respectively, whereas 80/10/10 ABS/PP/PA6 blends showed electrically insulating behavior even at 5 wt% of MWCNTs. Nonisothermal crystallization studies could detect the presence of MWCNTs in the PA6 and the PP phases. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers     

Application of styrene‐acrylonitrile random copolymer–polyarylate block copolymer as reactive compatibilizer for polyamide and acrylonitrile‐butadiene‐styrene blends

Styrene‐acrylonitrile random copolymer (SAN) and polyarylate (PAr) block copolymer were applied as a reactive compatibilizer for polyamide‐6 (PA‐6)/acrylonitrile‐butadiene‐styrene (ABS) copolymer blends. The SAN–PAr block copolymer was found to be effective for compatibilization of PA‐6/ABS blends. With the addition of 3.0–5.0 wt % SAN–PAr block copolymer, the ABS‐rich phase could be reduced to a smaller size than 1.0 μm in the 70/30 and 50/50 PA‐6/ABS blends, although it was several microns in the uncompatibilized blends. As a result, for the blends compatibilized with 3–5 wt % block copolymer the impact energy absorption reached the super toughness region in the 70/30 and 50/50 PA‐6/ABS compositions. The compatibilization mechanism of PA‐6/ABS by the SAN–PAr block copolymer was investigated by tetrahydrofuran extraction of the SAN–PAr block copolymer/PA‐6 blends and the model reactions between the block copolymer and low molecular weight compounds. The results of these experiments indicated that the SAN–PAr block copolymer reacted with the PA‐6 during the melt mixing process via an in situ transreaction between the ester units in the PAr chain and the terminal amine in the PA‐6. As a result, SAN–PAr/PA‐6 block copolymers were generated during the melt mixing process. The SAN–PAr block copolymer was supposed to compatibilize the PA‐6 and ABS blend by anchoring the PAr/PA‐6 and SAN chains to the PA‐6 and ABS phases, respectively. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2300–2313, 2002     

Melt‐mixed polypropylene/acrylonitrile‐butadiene‐styrene blends with multiwall carbon nanotubes: Effect of compatibilizer and modifier on morphology and electrical conductivity

Cocontinuous blends of 45/55 polypropylene (PP)/acrylonitrile‐butadiene‐styrene (ABS) with multiwall carbon nanotubes (MWNT) were prepared by melt‐mixing in a conical twin‐screw microcompounder. PP‐grafted‐maleic anhydride (PP‐g‐MA) and styrene MA were used as compatibilizers for PP/ABS blends. Scanning electron microscopic observations showed phase segregation of PP‐g‐MA in the blends. State of dispersion of MWNT in the presence or absence of the compatibilizers was assessed through AC electrical conductivity measurements and crystallization studies of the blends. An improvement in AC electrical conductivity was observed in blends in presence of either styrene MA or dual compatibilizers. The lowest electrical percolation threshold was achieved at 0.1 wt % of MWNT using sodium salt of 6‐amino hexanoic acid‐modified MWNT. Significant increase in crystallization temperature of PP phase of blends with MWNT was observed in the presence of compatibilizers as compared to blends without compatibilizers. An attempt has been made to address the complex issues of phase segregation, compatibilization, and dispersion of MWNT in cocontinuous blends of PP/ABS. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Electrical and mechanical properties of acrylonitrile‐butadiene‐styrene/multiwall carbon nanotube nanocomposites prepared by melt‐blending

The electrical properties in polymer/carbon nanotube (CNT) nanocomposites are governed not only by the degree of dispersion but also to a greater extent on the aspect ratio of the CNTs in the final composites. Melt‐mixing of polymer and CNTs at high shear rate usually breaks the CNTS that lowers the aspect ratio of the nanotubes. Thus, homogeneous dispersion of CNTs while retaining the aspect ratio is a major challenge in melt‐mixing. Here, we demonstrate a novel method that involves melt‐blending of acrylonitrile‐butadiene‐styrene (ABS) and in situ polymerized polystyrene (PS)/multiwalled CNT (MWCNT) nanocomposites, to prepare electrically conducting ABS/MWCNT nanocomposites with very low CNT loading than reported. The rationale behind choosing PS/MWCNT as blending component was that ABS is reported to form miscible blend with the PS. Thus, (80/20 w/w) ABS/(PS/MWCNT) nanocomposites obtained by melt‐blending showed electrical conductivity value ≈1.27 × 10^?6 S cm^?1 at MWCNT loading close to 0.64 wt %, which is quite lower than previously reported value for ABS/MWCNT system prepared via solution blending. Scanning electron microscopy and differential scanning calorimetry analysis indicated the formation of homogenous and miscible blend of ABS and PS. The high temperature (100°C) storage modulus of ABS (1298 MPa) in the nanocomposites was increased to 1696 MPa in presence of 0.64 wt % of the MWCNT. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

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.     

MWNT‐filled PC/ABS blends: Correlation of morphology with rheological and electrical response

A systematic study was done on morphological, electrical and rheological behavior of co‐continuous or dispersed‐type polycarbonate (PC)/acrylonitrile‐styrene‐butadiene (ABS) blends, containing different amounts of multiwalled carbon nanotubes (MWNT). The MWNTs gave substantial electrical conductivities to these nanocomposites at very low concentrations, owing to the effective melt processing method. Because of selective localization of MWNTs in the PC phase, along with double percolation phenomenon, the blend with co‐continuous morphology showed a lower electrical and rheological percolation threshold, higher melt viscosity and elasticity, as compared to the system with dispersed morphology. The morphology of both the blend systems was refined as a result of MWNTs incorporation but the morphology type remained unchanged. A typical role of compatibilizer in refining blend morphology was observed in both the systems. The electrical conductivity of the system filled with MWNTs in presence of compatibilizer, was lower than the systems filled with MWNTs only, which was attributed to role of compatibilizer in directing a part of MWNTs from PC matrix toward ABS phase. With increasing compatibilizer/MWNTs ratio, the influence of compatibilizer on morphology refinement and conductivity reduction was intensified. By comparing TEM micrograph of PC/SAN/MWNTs with that of PC/ABS/MWNTs, it was revealed that small portion of MWNTs was also located on polybutadiene rubber fraction of ABS. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 739‐748, 2013     

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     

Effect of compatibilizer in acrylonitrile‐butadiene‐styrene toughened nylon 6 blends: Ductile–brittle transition temperature

The ductile–brittle transition temperatures were determined for compatibilized nylon 6/acrylonitrile‐butadiene‐styrene (PA6/ABS) copolymer blends. The compatibilizers used for those blends were methyl methacrylate‐co‐maleic anhydride (MMA‐MAH) and MMA‐co‐glycidyl methacrylate (MMA‐GMA). The ductile–brittle transition temperatures were found to be lower for blends compatibilized through maleate modified acrylic polymers. At room temperature, the PA6/ABS binary blend was essentially brittle whereas the ternary blends with MMA‐MAH compatibilizer were supertough and showed a ductile–brittle transition temperature at ?10°C. The blends compatibilized with maleated copolymer exhibited impact strengths of up to 800 J/m. However, the blends compatibilized with MMA‐GMA showed poor toughness at room temperature and failed in a brittle manner at subambient temperatures. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2643–2647, 2003     

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     

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     

Rheology,morphology, and crystallization behavior of melt‐mixed blends of polyamide6 and acrylonitrile‐butadiene‐styrene: Influence of reactive compatibilizer premixed with multiwall carbon nanotubes

Blends of polyamide6 (PA6) and acrylonitrile butadiene styrene (ABS) were prepared in presence or absence of up to 5 wt % of a reactive compatibilizer [styrene maleic anhydride copolymer (SMA) modified with 5 wt % multiwall carbon nanotubes (MWNT)] by melt‐mixing using conical twin screw microcompounder where the ABS content was varied from 20 to 50 wt %. The melt viscosity of the blends was significantly enhanced in presence of SMA modified by multiwall carbon nanotubes due to the reactive compatibilization, which leads to stabilized interphase in the blends. Furthermore, the presence of MWNT in the compatibilizer phase led to additional increase in viscosity and storage modulus. Morphological studies revealed the presence of either droplet‐dispersed or cocontinuous type depending on the blend compositions. Further, reactive compatibilization led to a significant change in the morphology, namely a structure refining, which was enhanced by MWNT presence as observed from SEM micrographs. DSC crystallization studies indicated a delayed crystallization response of PA6 in presence of ABS presumably due to high melt viscosity of ABS. The crystallization temperature and the degree of crystallinity were strongly dependent on the type of morphology and content of reactive compatibilizer, whereas the presence of MWNT had an additional influence. SAXS studies revealed the formation of thinner and less perfect crystallites of PA6 phase in the blends, which showed cocontinuous morphology. A unique observation of multiple scattering maxima at higher q region has been found in the blends of cocontinuous morphology, which was observed to be successively broadened in presence of the compatibilizer. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Blends of poly(2,6‐dimethyl‐1,4‐phenylene oxide)/polyamide 6 toughened by maleated polystyrene‐based copolymers: Mechanical properties,morphology, and rheology

Poly(2,6‐dimethyl‐1,4‐phenylene oxide)/polyamide 6 (PPO/PA6 30/70) blends were impact modified by addition of three kinds of maleated polystyrene‐based copolymers, i.e., maleated styrene‐ethylene‐butylene‐styrene copolymer (SEBS‐g‐MA), maleated methyl methacrylate‐butadiene‐styrene copolymer (MBS‐g‐MA), and maleated acrylonitrile‐butadiene‐styrene copolymer (ABS‐g‐MA). The mechanical properties, morphology and rheological behavior of the impact modified PPO/PA6 blends were investigated. The selective location of the maleated copolymers in one phase or at interface accounted for the different toughening effects of the maleated copolymer, which is closely related to their molecular structure and composition. SEBS‐g‐MA was uniformly dispersed in PPO phase and greatly toughened PPO/PA6 blends even at low temperature. MBS‐g‐MA particles were mainly dispersed in the PA6 phase and around the PPO phase, resulting in a significant enhancement of the notched Izod impact strength of PPO/PA6 blends from 45 J/m to 281 J/m at the MBS‐g‐MA content of 20 phr. In comparison, the ABS‐g‐MA was mainly dispersed in PA6 phase without much influencing the original mechanical properties of the PPO/PA6 blend. The different molecule structure and selective location of the maleated copolymers in the blends were reflected by the change of rheological behavior as well. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Polylactide toughening with epoxy‐functionalized grafted acrylonitrile–butadiene–styrene particles

Glycidyl methacrylate functionalized acrylonitrile–butadiene–styrene (ABS‐g‐GMA) particles were prepared and used to toughen polylactide (PLA). The characteristic absorption at 1728 cm^?1 of the Fourier transform infrared spectra indicated that glycidyl methacrylate (GMA) was grafted onto the polybutadiene phase of acrylonitrile–butadiene–styrene (ABS). Chemical reactions analysis indicated that compatibilization and crosslinking reactions took place simultaneously between the epoxy groups of ABS‐g‐GMA and the end carboxyl or hydroxyl groups of PLA and that the increase of GMA content improved the reaction degree. Scanning electron microscopy results showed that 1 wt % GMA was sufficient to satisfy the compatibilization and that ABS‐g‐GMA particles with 1 wt % GMA dispersed in PLA uniformly. A further increase of GMA content induced the agglomeration of ABS‐g‐GMA particles because of crosslinking reactions. Dynamic mechanical analysis testing showed that the miscibility between PLA and ABS improved with the introduction of GMA onto ABS particles because of compatibilization reactions. The storage modulus decreased for the PLA blends with increasing GMA content. The decrease in the storage modulus was due to the chemical reactions in the PLA/ABS‐g‐GMA blends, which improved the viscosity and decreased the crystallization of PLA. A notched impact strength of 540 J/m was achieved for the PLA/ABS‐g‐GMA blend with 1 wt % GMA, which was 27 times than the impact strength of pure PLA, and a further increase in the GMA content in the ABS‐g‐GMA particles was not beneficial to the toughness improvement. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Polyamide/Polystyrene Blend Compatibilisation by Montmorillonite Nanoclay and its Effect on Macroporosity of Gas Diffusion Layers for Proton Exchange Membrane Fuel Cells

This work deals with a new route to modify polymer blend morphology in order to improve the porosity of gas diffusion layers (GDLs) for proton exchange membrane fuel cells (PEMFCs). First, electrically conductive polymer‐based blends were carefully formulated using a twin‐screw extrusion process. Blend electrical conductivity was ensured by the addition of high specific surface area carbon black and synthetic graphite flakes. Final GDL porosity, in particular its macroporosity, was generated by melt blending polyamide 11 (PA11) matrix with polystyrene (PS) followed by PS extraction with tetrahydrofuran (THF) solvent at room temperature. In order to improve GDL porosity by the optimisation of PS dispersion in the PA11 matrix, PA11/PS blends were compatibilised by the addition of 2 wt.‐% of clay. It was observed that both macroporosity and pore size distribution were beneficially modified after blend compatibilisation. Final GDL conductivity of about 1.25 S cm^–1, a porosity of 53% and a specific pore surface area of 75 m² g^–1 were achieved.     

Electroconductive polyblend fibers of polyamide‐6/polypropylene/polyaniline: Electrical,morphological, and mechanical characteristics

Melt spun drawn fibers were prepared using a ternary blend of PP/PA6/PANI‐complex (polypropylene/polyamide‐6/polyaniline‐complex). Their electrical and mechanical properties were compared to those of binary blend fibers of PP/PANI‐complex. The results of the morphological studies on 55:25:20 PP/PA6/PANI‐complex ternary fibers were found to be in accordance with the predicted morphology for the observed conductivity vs. fiber draw ratio. The scanning electron microscopy (SEM) micrographs of the ternary blend illustrated at least a three‐phase morphology of a matrix/core‐shell dispersed phase style, with widely varying sizes of droplets. This resulted in a dispersed morphology that, in some parts of the blend, approached a bicontinuous/dispersed phase morphology due to coalescence of the small droplets. The matrix was PP and the core‐shell dispersed phase was PA6 and PANI‐complex, in which a part of the PANI‐complex had encapsulated the PA6 phase and the remaining was solved/dispersed in the PA6 core, as later confirmed by X‐ray mapping. When the ternary blend fibers were compared to the binary fibers, the formers were able to combine better conductivity (of an order of 10^?3 S cm^?1) with a greater tensile strength only at a draw ratio of 5. This indicated that the draw ratio is more critical for the ternary blend fibers, because both conductivity and tensile strength depended on the formation of fibrils from the core‐shell dispersed phase of the PA6/PANI‐complex. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

Dynamic‐mechanical analysis of MWNTs‐filled PC/ABS blends

In a systematic manner, the roles of MWNTs as filler and styrene acrylonitrile copolymer‐graft‐maleic anhydride (SAN‐MA) as compatibilizer, individually and together, on dynamic‐mechanical behavior of polycarbonate (PC)‐rich/acrylonitrile butadiene styrene terpolymer (ABS) blend were studied. The investigations were performed using small‐scale mixing in a one‐step procedure with a fixed MWNTs content of 0.75 wt% and a blend composition of PC/ABS = 70/30 w/w. PC/SAN blends and nanocomposites as simpler model system for PC/ABS were also studied to reveal the role of the rubbery polybutadiene (PB) fraction. It is found that the tendency of MWNTs to localize within the PC component in compatibilized PC/ABS was lower than in compatibilized PC/SAN blends. Dynamic mechanical analysis (DMA) revealed the dual role of SAN‐MA as blend compatibilizer and also promoter of MWNTs migration towards PC, where SAN‐MA to MWNTs weight ratio varied between 1 and 4. At the compatibilizer/MWNTs weight ratio of 1, MWNTs localized in PC component of the blends whereas increasing the compatibilizer/MWNTs ratio to 4 led to migration of MWNTs toward SAN or ABS component. In DMA studies, loss modulus normalization of the nanocomposites revealed the coexistence of mobilized and immobilized regions within the nanocomposite structure, as a result of MWNTs and compatibilizer loading. POLYM. ENG. SCI., 54:2696–2706, 2014. © 2014 Society of Plastics Engineers     

Effect of EPDM‐g‐MAH on the morphology and properties of PA6/EPDM/HDPE ternary blends

The formation of core‐shell morphology within the dispersed phase was studied for composite droplet polymer‐blend systems comprising a polyamide‐6 matrix, ethylene‐propylene‐diene terpolymer (EPDM) shell and high density polyethylene (HDPE) core. In this article, the effect of EPDM with different molecular weights on the morphology and properties of the blends were studied. To improve the compatibility of the ternary blends, EPDM was modified by grafting with maleic anhydride (EPDM‐g‐MAH). It was found that core‐shell morphology with EPDM‐g‐MAH as shell and HDPE as core and separated dispersion morphology of EPDM‐g‐MAH and HDPE phase were obtained separately in PA6 matrix with different molecular weights of EPDM‐g‐MAH in the blends. DSC measurement indicated that there may be some co‐crystals in the blends due to the formation of core‐shell structure. Mechanical tests showed that PA6/EPDM‐g‐MAH/HDPE ternary blends with the core‐shell morphology exhibited a remarkable rise in the elongation at break. With more perfect core‐shell composite droplets and co‐crystals, the impact strength of the ternary blends could be greatly increased to 51.38 kJ m^?2, almost 10 times higher than that of pure PA6 (5.50 kJ m^?2). POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers