Effects of olefin‐based compatibilizers on the morphology,thermal and mechanical properties of ABS/polyamide‐6 blends

In this study, commercially available epoxidized and maleated olefinic copolymers, EMA‐GMA (ethylene‐methyl acrylate‐glycidyl methacrylate) and EnBACO‐MAH (ethylene‐n butyl acrylate‐carbon monoxide‐maleic anhydride), were used at 0, 5, and 10% by weight to compatibilize the blend composed of ABS (acrylonitrile‐butadiene‐styrene) terpolymer and PA6 (polyamide 6). Compatibilizing performance of these two olefinic polymers was investigated from blend morphologies, thermal and mechanical properties as a function of blend composition, and compatibilizer loading level. Scanning electron microscopy (SEM) studies showed that incorporation of compatibilizer resulted in a fine morphology with reduced dispersed particle diameter at the presence of 5% compatibilizer. The crystallization behavior of PA6 phase in the blends was explored for selected blend compositions by differential scanning calorimetry (DSC). At high compatibilizer level a decrease in the degree of crystallization was observed. In 10% compatibilizer containing blends, formation of γ‐crystals was observed contrary to other compatibilizer compositions. The behavior of the compatibilized blend system in tensile testing showed the negative effect of using excess compatibilizer. Different trends in yield strengths and strain at break values were observed depending on compatibilizer type, loading level, and blend composition. With 5% EnBACO‐MAH, the blend toughness was observed to be the highest at room temperature. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 926–935, 2007     

Compatibilization of polyethylene/polyamide 6 blends with oxazoline‐functionalized polyethylene and styrene ethylene/butylene styrene copolymer (SEBS)

Study was made of the compatibilization of polyethylene/polyamide 6 (PE/PA6) blends with a ricinoloxazoline maleinate grafted polyethylene and styrene ethylene/butylene styrene copolymer. The blends were prepared in a twin‐screw midiextruder, and the specimens for mechanical tests were injection molded with a mini‐injection molding machine. The effect of compatibilizing on the mechanical properties and the morphology of the blends was studied. The toughness and ductility of the blends were substantially improved as a result of the compatibilization. Simultaneously, the strength and stiffness were slightly reduced. Morphological studies showed that the particle size was reduced and the adhesion of the dispersed phase to the matrix was improved by the compatibilization. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1443–1450, 1999     

Use of oxazoline functionalized polyolefins and elastomers as compatibilizers for thermoplastic blends

Oxazoline functionalized polypropylene, polyethylene, ethylene propylene copolymer (E/P), and styrene ethylene/butylene styrene copolymer (SEBS) were studied as compatibilizers in blends of polyolefins with polyesters and polyamides. The blends investigated were polypropylene/polyamide 6, polypropylene/polybutylene terephtalate, and polyethylene/polyamide 6, with engineering thermoplastic contents of 30 wt %. The blends were prepared in a twin-screw midiextruder, and injection molded with a mini-injection molding machine. The effect of compatibilizing on the morphology and mechanical properties of the blends was of interest. Compatibilization substantially improved the toughness of all tested blends. Their strength and stiffness remained at the level of the binary blends when polypropylene or polyethylene based compatibilizers were used, but slightly decreased with other compatibilizers. Morphological studies showed that the particle size was reduced, and the adhesion of the dispersed phase to the matrix improved by compatibilization. The effect of unfunctionalized polyethylene, polypropylene, E/P, and SEBS was also studied to compare the compatibilizers with them. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 1923–1930, 1998     

In situ compatibilization of polypropylene/polystyrene blend by controlled degradation and reactive extrusion

In situ compatibilization of polypropylene (PP) and polystyrene (PS) was achieved by combinative application of tetraethyl thiuram disulfide (TETD) as degradation inhibitor and di‐tert‐butyl peroxide as degradation initiator in the process of reactive extrusion. The PP/PS blends obtained were systematically investigated by rheological measurement, scanning electron microscopy, and differential scanning calorimetry. The results indicate that peroxide‐induced degradation of PP can be effectively depressed by adding TETD, which may favor the formation of PP‐g‐PS copolymer during melt processing. The PP‐g‐PS copolymer formed may act as an in situ compatibilizer for PP/PS blends, and subsequently decreases the size of dispersed PS phase and changes both rheological and thermal properties of the blends. Based on the present experimental results, the mechanisms for the controlled degradation of PP and in situ formation of PP‐g‐PS copolymer in the PP/PS blends have been proposed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

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     

Polypropylene–phenol formaldehyde‐based compatibilizers. II. Application in PP/PA6 75/25 (wt/wt) blends

A new class of compatibilizers suitable for blends or alloys of polypropylene and engineering polymers having aromatic residues or functionality complimentary to hydroxyl were evaluated in blends of isotatctic polypropylene (PP) and polyamide 6 (PA6). The compatibilizer consisted of a PP part with a phenol formaldehyde (PF) polymer grafted onto it. In this study, various combinations of the polymer parameter of each compatibilizer building block were examined. Based on the same loading, the compatibilizer with low molecular weight PP and high content of high molecular weight PF was observed to be the most efficient. A compatibilizer content of up to 7.5% by weight gave significant reduction in the average particle size of the dispersed PA phase. Similarly, corresponding improvements in the mechanical properties were observed as the average particle size was reduced. For some of the blends, more than additive improvement in the mechanical properties were achieved. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 355–360, 2000     

Influence of in situ compatibilization on in situ formation of low‐density polyethylene/polyamide 6 blends by reactive extrusion

Low‐density polyethylene/polyamide 6 (LDPE/PA6) blends were in situ formed by reactive extrusion, in which in situ polymerization of ε‐caprolactam (CL) and in situ copolymerization of maleic anhydride grafted low‐density polyethylene (LDPE‐MA) and CL took place simultaneously. The latter reaction could be considered as in situ compatibilization, and the influence of in situ compatibilization on the morphologies, thermal properties, and rheological behaviors of the blends was investigated in this work. Scanning electron microscopy showed that the in situ compatibilization could dramatically reduce the dispersed phase sizes and narrow the size distribution. The thermal properties indicated that in differential scanning calorimetry (DSC) cooling scans, fractionated crystallization of the PA6 component was observed in all cases and was promoted with increasing the amount of LDPE‐MA. The DSC second heating scans showed the in situ compatibilization could stimulate the formation of the less stable γ‐crystalline form of PA6 in the blends. Dynamic rheological experiments revealed the in situ compatibilization had enhanced the viscosity, storage modulus, and loss modulus of the blend and reduce the corresponding slope values of the storage modulus and loss modulus. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Oxygen permeation through films of compatibilized polypropylene/polyamide 6 blends

Polypropylene/polyamide 6 blends were prepared by melt mixing, without or with the addition of a suitable commercial product, a polypropylene grafted with 1% maleic anhydride, used as an interfacial modifier. The oxygen permeation through their films was studied as a function of temperature and the effect of the presence of the compatibilizer on the barrier properties of the material was examined. In addition, the diffusion coefficients were measured. The relationships between transport parameters and blend morphology were investigated by microscopic observations, together with chemical etchings, and a simple model was applied for interpreting the experimental permeation data. Differential scanning calorimetry was used in the determination of the degree of crystallinity of the blends. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1941–1949, 1999     

Comparison of olefin copolymers as compatibilizers for polypropylene and high‐density polyethylene

Some polyolefin elastomers were compared as compatibilizers for blends of polypropylene (PP) with 30 wt % high‐density polyethylene (HDPE). The compatibilizers included a multiblock ethylene–octene copolymer (OBC), two statistical ethylene–octene copolymers (EO), two propylene–ethylene copolymers (P/E), and a styrenic block copolymer (SBC). Examination of the blend morphology by AFM showed that the compatibilizer was preferentially located at the interface between the PP matrix and the dispersed HDPE particles. The brittle‐to‐ductile (BD) transition was determined from the temperature dependence of the blend toughness, which was taken as the area under the stress–strain curve. All the compatibilized blends had lower BD temperature than PP. However, the blend compatibilized with OBC had the best combination of low BD temperature and high toughness. Examination of the deformed blends by scanning electron microscopy revealed that in the best blends, the compatibilizer provided sufficient interfacial adhesion so that the HDPE domains were able to yield and draw along with the PP matrix. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

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     

Melt rheological properties of polypropylene–maleated polypropylene blends. I. Steady flow by capillary

Melt rheological properties of blends of polypropylene (PP) and PP grafted with maleic anhydride (PP‐g‐MA) are studied using a capillary rheometer. A pseudoplastic flow behavior is observed. The pseudoplasticity of the melt reduces with an increase of PP‐g‐MA content and/or temperature. The PP‐g‐MA component in the blend acts as decreasing melt viscosity, especially in the lower shear rate region, while the addition of PP‐g‐MA to PP does not cause obvious increase of die swell ratio. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1641–1648, 1999     

Effect of the type of nylon chain‐end on the compatibilization of PP/PP‐GMA/nylon 6 blends

Polyamide and polypropylene (PP) are two important classes of commercial polymers; however, their direct mixing leads to incompatible blends with poor properties. Polypropylene functionalized with glycidyl methacrylate (PP‐GMA) was used as a compatibilizer in blends of PP and nylon 6, because of the possible reaction of ? NH₂ and ? COOH groups with the epoxide group of GMA. Two types of nylon 6 with different ratios between ? NH₂ and ? COOH groups were used. The one with higher concentration of ? COOH groups was less compatible with PP in a binary blend. When PP‐GMA was used as a compatibilizer, a better dispersion of nylon in the PP matrix was obtained together with better mechanical properties for both nylons used in this work. © 2001 Society of Chemical Industry     

Effect of a tie layer on the delamination toughness of polypropylene and polyamide‐66 microlayers

The effect of a thin tie layer on the adhesion of polypropylene (PP) and polyamide‐66 (PA) was studied by delamination of microlayers. The microlayers consisted of many alternating layers of PP and PA separated by a thin layer of a maleated PP. The peel toughness and delamination failure mode were determined using the T‐peel test. Without a tie layer, there was no adhesion between PP and PA. A tie layer with 0.2% MA provided some adhesion; however, delamination occurred by interfacial failure. Increasing the maleic anhydride (MA) content of the tie layer increased the interfacial toughness. With 0.5% MA, the interfacial toughness exceeded the craze condition of PP, and a transition from interfacial delamination to craze delamination occurred. Crazing ahead of the crack tip effectively reduced the stress concentration at the interface and dramatically increased the delamination toughness. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1461–1467, 1999     

Chemical structure and compatibility of polyamide–chitin and chitosan blends

This work presents a comparative study of the compatibilization of four binary blends with slight differences in their chemical structures. The natural polymers chitin (QA) and chitosan (QN) are blended with polyamide 6 (PA6) and polyamide 66 (PA66). The results, obtained using differential scanning calorimetry, infrared spectroscopy, and light and scanning electron microscopy, gave the following compatibilization sequence: PA6/QN ≈ PA66/QN > PA6/QA > PA66/QA. This behavior could be related to the ability of QN to form hydrogen bonds and also to the capability of the packing of PA66. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 850–857, 2000     

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     

Toughening of polypropylene with styrene/ethylene‐butylene/styrene tri‐block copolymer: Effects of reactive and nonreactive compatibilization

The effects of compatibilization on the toughening of polypropylene (PP) by melt blending with styrene/ethylene‐butylene/styrene tri‐block copolymer (SEBS) in a twin‐screw extruder were investigated. The compatibilizers used were SEBS functionalized with maleic anhydride (SEBS‐g‐MA), PP functionalized with acrylic acid (PP‐g‐AA), and bifunctional compound p‐phenylenediamine (PPD). The effects of the compatibilization were evaluated through the mechanical properties as well as through the determination of the phase morphology of the blends by scanning electron microscopy. Reactive compatibilized blends show up to a 30‐fold increase in impact strength compared with neat PP; likely the result of the reaction of the bifunctional compound (PPD) with the acid acrylic and maleic anhydride groups, this increase in strength rendered both morphological and mechanical stability to these blends. The addition of PPD to the blends significantly changed their phase morphologies, leading to larger average diameters of the dispersed particles, probably as a result of the morphological stabilization at the initial processing steps during extrusion, with the occurrence of chemical reactions. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3466–3479, 2002     

Effect of various added compatibilizers on the crystalline structure of polypropylene homopolymer/polybutylene terephthalate and polypropylene copolymer/polybutylene terephthalate polymer blends

Blends of semicrystalline isotactic polypropylene homopolymer and polypropylene copolymer with polybutylene terephthalate with different compatibilizers [i.e., styrene acrylonitrile, Surlyn, styrene–ethylene–butadiene styrene (SEBS), block copolymer and SEBS block copolymer grafted with maleic anhydride] were prepared by melt blending. Wide angle‐X‐ray scattering patterns of injection moldings were obtained. The crystallinity index and d‐spacing were calculated with different concentrations of different compatibilizers. X‐ray results in the structural investigation of the compatibilized blends correlated well with the different compatibilizer concentrations. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1190–1193, 2003     

Novel reactive compatibilization strategy on immiscible polypropylene and polystyrene blend

Polypropylene (PP) and polystyrene (PS) are immiscible and incompatible. Since both PP and PS components possess no reactive functional group, reactive compatibilization of a PP/PS blend is impossible unless certain reactive functional groups are imparted to either PP or PS. In this study we provide a simple approach to reactively compatibilize the nonreactive PP/PS blend system by physically functionalizing PP and PS with the addition of maleic anhydride grafted PP (PP‐g‐MA) and styrene maleic anhydride random copolymer (SMA), respectively. An epoxy monomer, serving as a coupler and possessing four epoxy groups able to react with the maleic anhydride of PP‐g‐MA and SMA, was then added during melt blending. Observations of the finer PS domain sizes and improved mechanical properties support the plausibility of reactive compatibilization of this nonreactive PP/PS blend by combining physically functionalized PP and PS with tetra‐glycidyl ether of diphenyl diamino methane (TGDDM) in a one‐step extrusion process. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Mechanical,thermal, and microstructural properties of polypropylene/polyamide‐6/styrene‐ethylene‐butadiene‐styrene polymer alloys

Interfacial agents as compatibilizers have recently been introduced into polymer blends to improve the microstructure and mechanical properties of thermoplastics. In this way, it is possible to prepare a mixture of polymeric materials that can have superior mechanical properties over a wide temperature range. In this study, an incompatible blend of polypropylene (PP) and polyamide‐6 (PA₆) were made compatible by the addition of 10% styrene–ethylene–butadiene–styrene copolymer (SEBS). The mixing operation was conducted by using a twin‐screw extruder. The morphology and the compatibility of the mixtures were examined by SEM and DSC techniques. Furthermore, the elastic modulus, tensile and yield strengths, percentage elongation, hardness, melt flow index, Izod impact resistance, heat deflection temperature (HDT), and Vicat softening point values of polymer alloys of various ratios were determined. It was found that the addition of SEBS to the structures decreased the tensile strength, yield strength, elastic modulus, and hardness, whereas it increased the Izod impact strength and percentage elongation values. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3485–3491, 2003     

Crystallization behavior of PP/PP‐g‐MAH/GFR PA66 blends: Establishment of their continuous‐cooling‐transformation of relative crystallinity diagrams

Polypropylene/polypropylene‐grafted‐maleic anhydride/glass fiber reinforced polyamide 66 (PP/PP‐g‐MAH/GFR PA 66) blends‐composites with and without the addition of polypropylene‐grafted‐maleic anhydride (PP‐g‐MAH) were prepared in a twin screw extruder. The effect of the compatibilizer on the thermal properties and crystallization behavior was determined using differential scanning calorimetry analysis. The hold time was set to be equal to 5 min at 290°C. These conditions are necessary to eliminate the thermomechanical history in the molten state. The crystallization under nonisothermal conditions and the plot of Continuous‐Cooling‐Transformation of relative crystallinity diagrams of both PP and PA 66 components proves that PP is significantly affected by the presence of PP‐g‐MAH. From the results it is found that an abrupt change is observed at 2.5 wt % of PP‐g‐MAH as a compatibilizer and then levels off. In these blends, concurrent crystallization behavior was not observed for GFR PA66. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1620–1626, 2007