Morphology of compatibilized ternary blends of polypropylene,nylon 66, and polystyrene

The morphologies of a ternary blend of nylon 66 and polystyrene in a polypropylene matrix with and without compatibilization by an ionomer resin (for nylon 66) and a styrene‐block‐ethylene‐co‐butylene‐block‐styrene (SEBS) copolymer (for polystyrene) were investigated by transmission electron microscopy (TEM) of stained thin sections. The morphology found with the two compatibilizers (a five‐component mixture) was essentially that of the binary blends of nylon 66/polypropylene and of polystyrene/polypropylene with their respective compatibilizers, indicating no gross interference between the two compatibilization systems. However, several interactions were discerned: 1) an association of the polystyrene with the nylon in the compatibilized blends (partial wetting), 2) a presence of larger particles when both compatibilizers were added to the binary blends, and 3) a possible synergism, in which less of each compatibilizer was needed when they were both present. Polym. Eng. Sci. 46:385–398, 2006. © 2006 Society of Plastics Engineers.     

Relationship between morphology and mechanical properties of binary and compatibilized ternary blends of polypropylene and nylon 6

The effect of compatibilization on the morphology, mechanical properties, and dynamic mechanical properties of isotactic polypropylene (IPP)/nylon-6 (Ny-6) binary blends was investigated. Maleic anhydride (MAH) functionalized IPP was used as a compatibilizer in binary blends. The morphological, mechanical, and dynamic mechanical properties of binary and ternary blends were compared. The blends containing IPP-g-MAH showed more regular and finer dispersion of phases, different dynamic properties, and improved mechanical properties due to better adhesion between the two phases. The blends were also characterized for their flow properties and extent of water absorption. The melting peak temperature and percent crystallinity of IPP and Ny-6 phases were decreased in compatibilized blends. © 1996 John Wiley & Sons, Inc.     

Phase morphology,thermomechanical, and crystallization behavior of uncompatibilized and PP‐g‐MAH compatibilized polypropylene/polystyrene blends

In this article, we discuss the phase morphology, thermal, mechanical, and crystallization properties of uncompatibilized and compatibilized polypropylene/polystyrene (PP/PS) blends. It is observed that the Young's modulus increases, but other mechanical properties such as tensile strength, flexural strength, elongation at break, and impact strength decrease by blending PS to PP. The tensile strength and Young's modulus of PP/PS blends were compared with various theoretical models. The thermal stability, melting, and crystallization temperatures and percentage crystallinity of semicrystalline PP in the blends were marginally decreased by the addition of amorphous PS. The presence of maleic anhydride‐grafted polypropylene (compatibilizer) increases the phase stability of 90/10 and 80/20 blends by preventing the coalescence. Hence, finer and more uniform droplets of PS dispersed phases are observed. The compatibilizer induced some improvement in impact strength for the blends with PP matrix phase, however fluctuations in modulus, strength and ductility were observed with respect to the uncompatibilized blend. The thermal stability was not much affected by the addition of the compatibilizer for the PP rich blends but shows some decrease in the thermal stability of the blends, where PS forms the matrix. On the other hand, the % crystallinity was increased by the addition of compatibilizer, irrespective of the blend concentration. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42100.     

Dynamically cured polypropylene/Novolac blends compatibilized with maleic anhydride‐g‐polypropylene

In this article, the dynamic vulcanization process was applied to polypropylene (PP)/Novolac blends compatibilized with maleic anhydride‐grafted PP (MAH‐g‐PP). The influences of dynamic cure, content of MAH‐g‐PP, Novolac, and curing agent on mechanical properties of the PP/Novolac blends were investigated. The results showed that the dynamically cured PP/MAH‐g‐PP/Novolac blend had the best mechanical properties among all PP/Novolac blends. The dynamic cure of Novolac improved the modulus and stiffness of the PP/Novolac blends. The addition of MAH‐g‐PP into dynamically cured PP/Novolac blend further enhanced the mechanical properties. With increasing Novolac content, tensile strength, flexural modulus, and flexural strength increased significantly, while the elongation at break dramatically deceased. Those blends with hexamethylenetetramine (HMTA) as a curing agent had good mechanical properties at HMTA content of 10 wt %. Scanning electron microscopy (SEM) analysis showed that dynamically cured PP/MAH‐g‐PP/Novolac blends had finer domains than the PP/MAH‐g‐PP/Novolac blends. Thermogravimetric analysis (TGA) results indicated that the incorporation of Novolac into PP could improve the thermal stability of PP. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Effects of mixing porcedures on properties of compatibilized polypropylene/nylon 6 blends

The paper consides the effects of compatibilization with maleic anhydride grafted polypropylene (PP-g-MAH) on the propertie of immiscible blends of polypropylene (PP) and nylon 6 (N6). We prepared the blends by three different mixing processes; single-step blending, two-step blending with reactive premixing, and two-step blending with nonreactive premixing, to determine the effective mixiing process for fine morphological structure thermal stability, and mechanical properties. Dynamic melt reheological properties were measured to examine the modification of elastic properties by the compatibilizer. In addtion, thermal analysis was also carried out to detect the change in crystallization and thereby to probe the degree of compatibilizaton. The results show that compatibilized blends prepared by teh single-step process exhibit improved phase morphology, thermal stability, and mechanical properties for dried conditions, compared with other blend types. Finally, the water absorption test indicates that the added compatibilizer yields enhanced water resistance in spite of the strong intrinsic hydrophilicity of N6. In particular, two-step blending with reactive premixing is most effective in improving water resistance and reducing degradation of mechanical properties after moisture absorption.     

Morphology and mechanical properties of polypropylene/polystyrene blends compatibilized with styrene–butadiene block copolymers

The effect of molecular structure of styrene–butadiene block (SB) copolymers on the morphology, tensile properties, impact strength, and microhardness of polypropylene/polystyrene (PP/PS) (80/20) blends was studied. The addition of SB copolymers substantially reduces the size of dispersed PS particles formed at mixing. The distribution of SB copolymers between the interface and bulk phases is controlled by the length of styrene blocks in SB, but a decrease in the size of PS particles at mixing correlates with total molecular weight of SB copolymers. For a substantial part of compatibilized blends, PS particles aggregate rapidly during compression molding and form honeycomb‐like particles split by SB partitions, which persist at further annealing. Aggregation of PS particles continues slowly at further annealing. Blends containing PS particles with well‐developed honeycomb structure show lower yield stress, higher plasticity, and lower tensile impact strength than the blends having PS particles with simple or undeveloped honeycomb structure. Microhardness of PP/PS blends is additive and of PP/PS/SB blends is lower than the additive due to the effect of SB copolymers on crystalline structure of PP matrix. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers     

Nonisothermal crystallization kinetics of polypropylene/polypropylene‐g‐polystyrene/polystyrene blends

The nonisothermal crystallization kinetics of polypropylene (PP), PP/polystyrene (PS), and PP/PP‐g‐PS/PS blends were investigated with differential scanning calorimetry at different cooling rates. The Jeziorny modified Avrami equation, Ozawa method, and Mo method were used to describe the crystallization kinetics for all of the samples. The kinetics parameters, including the half‐time of crystallization, the peak crystallization temperature, the Avrami exponent, the kinetic crystallization rate constant, the crystallization activation energy, and the F(T) and a parameters were determined. All of the results clearly indicate that the PP‐g‐PS copolymer accelerated the crystallization rate of the PP component in the PP/PP‐g‐PS/PS blends. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Co-continuous and encapsulated three phase morphologies in uncompatibilized and reactively compatibilized polyamide 6/polypropylene/polystyrene ternary blends using two reactive precursors

Phase morphology development in ternary uncompatibilized and reactively compatibilized blends based on polyamide 6 (PA6), polypropylene (PP) and polystyrene (PS) has been investigated. Reactive compatibilization of the blends has been performed using two reactive precursors; maleic anhydride grafted polypropylene (PP-g-MA) and styrene maleic anhydride copolymer (SMA) for PA6/PP and PA6/PS pairs, respectively. For comparison purposes, uncompatibilized and reactively compatibilized PA6/PP and PA6/PS binary blends, were first investigated. All the blends were melt-blended using a co-rotating twin-screw extruder. The phase morphology investigated using scanning electron microscope (SEM) and selective solvent extraction tests revealed that PA6/PP/PS blends having a weight percent composition of 70/15/15 is constituted from polyamide 6 matrix in which are dispersed composite droplets of PP core encapsulated by PS phase. Whereas, a co-continuous three-phase morphology was formed in the blends having a composition of 40/30/30. This morphology has been significantly affected by the reactive compatibilization. In the compatibilized PA6/(PP/PP–MA)/(PS/SMA) blends, PA6 phase was no more continuous but gets finely dispersed in the PS continuous phase. The DSC measurements confirmed the dispersed character of the PA6 phase. Indeed, in the compatibilized PA6/(PP/PP–MA)/(PS/SMA) blends where the PA6 particle size was smaller than 1 μm, the bulk crystallization temperature of PA6 (188 °C) was completely suppressed and a new crystallization peak emerges at a lower temperature of 93 °C as a result of homogeneous nucleation of PA6.     

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     

Fine disperse dyeable polypropylene fiber from polypropylene/polystyrene nano‐ceria blends

The blend of polypropylene (PP) and atactic polystyrene (PS) hybrid with nano‐ceria (CeO₂) was prepared for fine dyeable fiber. Nano‐CeO₂ modified with stearic acid was in situ added to PS by radical suspension polymerization. The dispersion of hy‐PS with nano‐CeO₂ in the PP crystals was investigated. The rheological behavior of the blend was similar to that of PP under the testing conditions, and the blend had stable spinning and drawing processability. The fine modified PP filaments were processed from the blend and had practical mechanical properties. The dyeability of the knitting fabrics from these filaments was studied. The increased amorphous content and the interface between PP and hy‐PS allowed the dye to penetrate the fiber, and the modified PP fiber had strong affinity to dye because of the complexation between cerium and dye. These effects resulted in improving K/S value and color fastness to soaping. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Mechanical properties of compatibilized nylon 6/polypropylene blends; studies of the interfacial behavior through an emulsion model

The high interfacial tension between two immiscible phases in a polymer blend often prevents a homogenous stress distribution. Therefore, blends of Nylon 6 (Ny6) and polypropylene (PP) were compatibilized using two commercially available types of PP grafted with maleic anhydride (MAPP) with a low (～2 %) and a high (～7%) grade of maleation. The interfacial tension of compatibilized and non‐compatibilized blends of PA6/PP was calculated from the recoded data of oscillatory rheological measurements using an emulsion model. Both compatibilizers showed similar improvements in tensile strength of up to 25%, but the one low maleation grade compatibilizer showed improved impact properties (>200%). It could be shown that, despite, being more effective in reducing the interfacial tension, using a high grade of maleation in the compatibilizer causes no additional improvement in tensile strength over a low grade of maleation and even has a negative effect on the PA6/PP blend impact strength. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40792.     

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

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

Characterization of carbon black‐filled immiscible polypropylene/polystyrene blends

The electrical and rheological behaviors of carbon black (CB)‐filled immiscible polypropylene (PP)/polystyrene (PS) blends were investigated. The compounding sequence influences the phase morphology of the ternary CB/PP/PS composites and the distribution of CB aggregates. Simultaneous measurements of resistance and dynamic modulus were carried out to monitor the phase coalescence of the ternary composites and CB migration and agglomeration in the PS phase during annealing at temperatures above the melting point of PP. The variation of resistivity is mainly attributed to CB agglomeration in the PS phase and the interfacial region, while the variation of dynamic modulus is regarded as the superimposition of the phase coalescence and CB agglomeration in the PS phase. The ternary composites with the majority of CB particles distributed in the interfacial region show the lowest conductive percolation threshold and the most stable resistivity–temperature performance during heating–cooling cycles. Copyright © 2011 Society of Chemical Industry     

Anisotropy and instability of the co-continuous phase morphology in uncompatibilized and reactively compatibilized polypropylene/polystyrene blends

The present work describes the anisotropy and instability observed upon the formation of co-continuous phase morphologies in model polystyrene/polypropylene melt-extruded blends. Uncompatibilized and reactively compatibilized blends using amino-terminated polystyrene, PS-NH₂, and maleic anhydride grafted polypropylene, PP-MAh, reactive precursors were investigated. Differences in phase morphology are discussed based on the viscoelastic properties of the components used, the blend composition and, the type and content of the compatibilizer precursor employed. As expected, for the same polystyrene grade at a concentration in the blend below 20 wt%, a polypropylene matrix having a higher viscosity enables the formation of a more co-continuous phase morphology than a less viscous one, as quantified by solvent extraction. The co-continuous phase morphology developed was found to exhibit a highly elongated structure upon melt flow through the die of the extruder. Isotropic co-continuity, observed inside the barrel of extruder, was transformed into anisotropic phase co-continuity in the form of interconnected infinite strands of the minor phase highly oriented in the extrusion direction.When the blends were thermally annealed, a 50/50 PS/PP co-continuous blend exhibits a substantial phase coarsening from micro- to millimeter scale without alteration of the phase co-continuity. The reactive compatibilization of the polypropylene and the polystyrene phases using 5 wt% PP-graft-PS, reactively in situ generated was able to significantly retard the phase evolution process.     

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     

Glass transition phenomena in melt‐processed polystyrene/polypropylene blends

Blends of an amorphous and a semi‐crystalline polymer—polystyrene and polypropylene, respectively—were prepared by melt processing in an extruder at 220°C. These polymers are known to be immiscible and the composite morphologies were characterized by electron microscopy and thermal analysis. Fine micron‐scale morphologies, ranging from 0.5 to 20 microns were observed. Thermal analysis and dynamic mechanical analysis showed changes in both the polystyrene and polypropylene glass transition temperatures (T_g) over the composition range. The major effect was a sharp increase in polystyrene T_g with increasing polypropylene content in the blend. A T_g elevation of 5.5°C was observed at 85% polypropylene. The polypropylene T_g also increases with increasing polypropylene content, starting at a depressed value in discrete polypropylene domain environments and approaching the bulk polypropylene value after the phase inversion is crossed. Qualitative structural models are proposed based on spatial and mechanical interactions between the components. POLYM. ENG. SCI., 45:1187–1193, 2005. © 2005 Society of Plastics Engineers     

Morphology and deformation of compatibilized polystyrene low density polyethylene blends

This investigation deals with the morphology and tensile behavior of polystyrene/low density polyethylene blends compatibilized by hydrogenated styrene‐b‐butadiene‐b‐styrene triblock copolymer. The stress‐strain measurements indicate that blends with excellent toughness were achieved, due to the compatibilizing role of the triblock copolymer in the system. The morphology of the blends was observed by scanning electron microscopy (SEM), and the results show that the state of polystyrene changes from continuous phase to dispersed phase with increasing LDPE content. The correlation between mechanical properties and morphology is discussed. The morphologies of the tensile bars were also examined by SEM, and the deformation mechanisms of the blend were further analysed according to fractography. © 1999 Society of Chemical Industry     

Structure–microhardness correlation in blends of nylon 6/nylon 66 monofilaments

The microstructure (crystallinity, long spacing) and the micromechanical properties (microhardness H) of two series of nylon 6 and nylon 66 monofilaments and their blends were investigated as a function of annealing temperature T_A and uniaxial deformation in a wide composition range. In case of the homopolymers, the gradual rise of microhardness with T_A is interpreted in the light of the increasing values of the crystallinity α and the hardness of the crystals H_c. The depression of the hardness values of the blends from the additive behavior of the hardness of individual components is discussed in the basis of the crystallinity depression of one component by the second one and viceversa. Finally, the influence of drawing and pressing the blends at 130°C which leads to a hardness increase is also explained in the light of an increase in the H_c value of nylon 66 due to orientation. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 636–643, 2000     

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     

Polymer blends of poly(trimethylene terephthalate) and polystyrene compatibilized by styrene‐glycidyl methacrylate copolymers

The compatibilizing effects of styrene‐glycidyl methacrylate (SG) copolymers with various glycidyl methyacrylate (GMA) contents on immiscible blends of poly(trimethylene terephthalate) (PTT) and polystyrene (PS) were investigated using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and ¹³C‐solid‐state nuclear magnetic resonance (NMR) spectroscopy. The epoxy functional groups in the SG copolymer were able to react with the PTT end groups (? COOH or ? OH) to form SG‐g‐PTT copolymers during melt processing. These in situ–formed graft copolymers tended to reside along the interface to reduce the interfacial tension and to increase the interfacial adhesion. The compatibilized PTT/PS blend possessed a smaller phase domain, higher viscosity, and better tensile properties than did the corresponding uncompatibilized blend. For all compositions, about 5% GMA in SG copolymer was found to be the optimum content to produce the best compatibilization of the blend. This study demonstrated that SG copolymers can be used efficiently in compatibilizing polymer blends of PTT and PS. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2247–2252, 2003