Investigation of polymer blends of polyamide-6 and poly(methyl methacrylate) synthesized by RAFT polymerization

Morphological and thermal properties of immiscible and incompatible polymer blends of commercial polyamide-6 (PA-6) and poly(methyl methacrylate) (PMMA) synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization have been studied in the presence of a compatibilizer consisting of either a random copolymer of styrene-maleic anhydride (SMA) or a diblock copolymer poly(methyl methacrylate) and polystyrene (PMMA-PS) also synthesized via RAFT polymerization. Blends of PA-6/PMMA were obtained by extrusion mixing. During melt compounding in the extruder, the functional groups of the polymer components were reacted in the presence of a compatibilizer, which changed considerably the morphology of the blend. After compatibilization, particles of PMMA in the PA-6 were smaller and better dispersed. The morphology and thermal properties of the blends were characterized using scanning electron microscopy (SEM) and differential scanning calorimetry (DCS).     

Polymer blends of PET–PS compatibilized by SMA and epoxy dual compatibilizers

Poly(ethylene terephthalate) (PET) and polystyrene (PS) are immiscible and incompatible and have been well recognized. In this study, styrene maleic anhydride random copolymer (SMA–8 wt % MA) and tetra-glycidyl ether of diphenyl diamino methane (TGDDM) are employed as reactive dual compatibilizers in the blends of PET–PS. The epoxy functional groups of the TGDDM can react with PET terminal groups ( OH and  COOH) and anhydride groups of SMA at the interface to produce PET-co-TGDDM-co-SMA copolymers. SMA with low MA content is miscible with PS, whereas the PET segments are structurally identical with PET phase. Therefore, these in-situ-formed copolymers tend to anchor at the interface and act as effective compatibilizers of the blends. The compatibilized blends, depending on the amounts of TGDDM and SMA addition, result in smaller phase domain, higher viscosity, and improved mechanical properties. This study demonstrates that SMA and TGDDM dual compatibilizer can be utilized effectively in compatibilizing polymer blends of PET and PS. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2029–2040, 1999     

Studies on the Effect of Polyamide-6 onto Modified Polyphenylene Oxide Matrix in Presence of Fumaric Acid as a Compatibilizer

Polymer blends of modified polyphenylene oxide (mPPO) and polyamide-6 (PA-6) are immiscible and incompatible in nature. However fumaric acid (FA) is used as a compatibilizer for the compatibilizing of mPPO/PA-6 blend systems. During melt compounding functional groups of the polymer components were reacted in the presence of a compatibilizer in the extruder. The blends were characterized by using FTIR, SEM, and mechanical behavior testing. The concentration of FA compatibilizer varies inversely w.r.t. PA-6 concentration in the blend systems. However the blend composition of PA-6 (10%) shows good miscibility among the other blend systems under present study.     

Mechanical properties and morphology of LCP/ABS blends compatibilized with a styrene–maleic anhydride copolymer

A co‐polyester liquid crystalline polymer (LCP) was melt blended with an acrylonitrile–butadiene–styrene copolymer (ABS). LCP fibrils are formed and a distinct skin/core morphology is observed in the injection moulded samples. At higher LCP concentration (50 wt%), phase inversion occurs, where the dispersed LCP phase becomes a co‐continuous phase. While the tensile strength and Young's modulus remain unchanged with increasing LCP content up to 30 wt% LCP, a significant enhancement of the modulus at 50 wt% LCP is observed due to the formation of co‐continuous morphology. The blend modulus is lower than the values predicted by the rule of mixtures, suggesting a poor interface between the LCP droplets and ABS matrix. A copolymer of styrene and maleic anhydride (SMA) was added in the LCP/ABS blends during melt blending. It is observed that SMA has a compatibilizing effect on the blend system and an optimum SMA content exists for mechanical properties enhancement. SMA improves the interfacial adhesion, whereas excess of SMA reduces the LCP fibrillation. Copyright © 2003 Society of Chemical Industry     

Joint Effect of Compatibilizer and Organo-Montmorillonite on Compatibilization of Polyamide-6/Poly(phenylene oxide) Blend: Morphology and Properties

Compatibilizer (styrene–maleic anhydride copolymer, SMA) and organo-montmorillonite (OMMT) were introduced into immiscible polyamide-6 (PA6)/ poly(phenylene oxide) (PPO) blend to obtain quaternary nanocomposites simply by melt extrusion. OMMT tactoids formed in PA6/PPO/OMMT ternary blend would become smaller or disappear with the addition of SMA. Besides, viscosity of SMA compatibilized PA6/PPO blend decreased a lot with the addition of OMMT. Based on these results, a mechanism for joint effect of SMA and OMMT in compatibilizing PA6 and PPO was proposed. We further studied water absorption and tensile properties of the nanocomposites, which were in consistent with the proposed mechanism.     

Study of the properties of compatibilized ABS/PA6 blends using response surface methodology

Styrene‐(maleic anhydride) copolymer (SMA) compatibilized blends of acrylonitrile‐butadiene rubber (ABS) and polyamide 6 (PA6) with a variety of compositions and compatibilizer levels were prepared at various screw speeds in a corotating twin screw extruder. A Box–Behnken model for three variables, with three levels, was chosen as an experimental design, and the mechanical properties of the blends were considered as the responses. Each response was analyzed and formulated versus the considered factors by the use of response surface methodology. Impact resistance increased with increased SMA concentration and reduced screw speed. In compatibilized samples, with an increase in PA6 content, higher impact resistance was observed. Increasing PA6 content and SMA concentration, as well as decreasing screw speed, gave improvements in both tensile and flexural strengths. In each case, all of the correlations among factors were studied. Grafting of SMA was proved by detecting the graft copolymer (SMA‐PA6) formed through extraction in formic acid and FTIR spectroscopy. Compared with uncompatibilized blends, compatibilized samples displayed more uniform and finer particle sizes, thereby proving the compatibilizing effect of the graft copolymer. The asymmetry trend in dispersed particle size before and after the phase inversion became more differentiated in the presence of the compatibilizer. Adding SMA lowered the phase inversion composition (based on PA6), whereas higher screw speed increased it. J. VINYL ADDIT. TECHNOL., 2009. © 2009 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     

共混工艺对SMAH增容ABS/PA6共混物形态和力学性能的影响

以(苯乙烯/马来酸酐)共聚物(SMAH)为增容剂,研究了共混工艺对(丙烯腈/丁二烯/苯乙烯)共聚物/尼龙6(ABS/PA6)共混物聚集态结构和力学性能的影响。结果表明,ABS与PA6直接共混时相容性差;加入增容剂SMAH后,分散相尺寸变小且易均匀分散,显著改善了ABS/PA6共混物的力学性能。当ABS为连续相、PA6为分散相时,共混物的聚集态结构强烈地受共混工艺的影响,(ABS/SMAH)/PA6共混物的分散相尺寸最小、力学性能最优;当PA6为连续相、ABS为分散相时,共混物的聚集态结构基本不受共混工艺的影响。     

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     

SMA增容PPO／PA66合金的结构与性能 Ⅱ．力学和耐热性能

用马来酸酐接枝聚苯乙烯（SMA）增容PPO／PA66，能明显提高PPO／PA66共混物的强度，刚性和韧性，对于富PPO共混物尤为明显；共混物的热变形温度随PPO含量增加而升高，随SMA用量增加而降低，根据共混物形态结构随PPO和SMA含量的变化，对共混物的增容和增塑效应进行了分析，并讨论了其作用机理。     

PET/PP blending by using PP‐g‐MA synthesized by solid phase

In attempts to improve the compatibility of polypropylene (PP) with polyethylene terephthalate (PET), a maleic anhydride grafted PP (PP‐g‐MA) was evaluated as a compatibilizer in a blend of 30/70 wt % PP/PET. PP‐g‐MA was produced from isotactic homopolymer PP utilizing the technique of solid phase graft copolymerization. Qualitative confirmations of the grafting were made by Fourier transform infrared spectroscopy (FTIR). Three different weight percent of compatibilizer, PP‐g‐MA, i.e., 5, 10, and 15 wt % have been used in PP/PET blends. The compatibilizing efficiency for PP/PET blend was examined using differential scanning calorimetry (DSC), optical microscopy (OM), scanning electron microscopy (SEM) of crycrofractured surfaces, and energy dispersive X‐ray spectrum (EDAX). The results show that the grafted PP promotes a fine dispersed phase morphology, improves processability, and modifies the crystallization behavior of the polyester component. These effects are attributed to enhance phase interaction resulting in reduced interfacial tension. Also, the results show that the compatibilizing effects of the three amounts of grafted PP in blend are different and dependent on the amount used. Adding 10 wt % of compatibilizer into blend produced the finest dispersed morphology. Elemental analysis results show that PP is matrix. DSC determination revealed that the melting temperature (T_m) of the PET component declined to some extent by comparison with neat PET. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104, 3986–3993, 2007     

Effects of addition of acrylic compatibilizer on the morphology and mechanical behavior of amorphous polyamide/SAN blends

Amorphous polyamide (aPA)/acrylonitrile‐styrene copolymer (SAN) blends were prepared using methyl methacrylate‐maleic anhydride copolymer MMA‐MA as compatibilizer. The aPA/SAN blends can be considered as a less complex version of the aPA/ABS (acrylonitrilebutadiene‐styrene) blends, due to the absence of the ABS rubber phase in the SAN material. It is known that acrylic copolymer might be miscible with SAN, whereas the maleic anhydride groups from MMA‐MA can react in situ with the amine end groups of aPA during melt blending. As a result, it is possible the in situ formation of aPA‐g‐MMA‐MA grafted copolymers at the aPA/SAN interface during the melt processing of the blends. In this study, the MA content in the MMA‐MA copolymer and its molecular weight was varied independently and their effects on the blend morphology and stress–strain behavior were evaluated. The morphology of the blends aPA/SAN showed a minimum in the SAN particle size at low amounts of MA in the compatibilizer, however, as the MA content in the MMA‐MA copolymer was increased larger SAN particle sizes were observed in the systems. In addition, higher MA content in the compatibilizer lead to less ductile aPA/SAN blends under tensile testing. The results shown the viscosity ratio also plays a very important role in the morphology formation and consequently on the properties of the aPA/SAN blends studied. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Melt rheology and morphology of uncompatibilized and in situ compatibilized nylon‐6/ethylene propylene rubber blends

Melt rheology and morphology of nylon‐6/ethylene propylene rubber (EPR) blends were studied as a function of composition, temperature, and compatibilizer loading. Uncompatibilized blends with higher nylon‐6 content (N90 and N95) and rubber content (N5 and N10) had viscosities approximately intermediate between those of the component polymers. A very clear negative deviation was observed in the viscosity–composition curve over the entire shear rate range studied for blends having composition N30, N50, and N70. This was associated with the interlayer slip resulting from the high‐level incompatibility between the component polymers. The lack of compatibility was confirmed by fracture surface morphology, given that the dispersed domains showed no sign of adhesion to the matrix. The phase morphology studies indicated that EPR was dispersed as spherical inclusions in the nylon matrix up to 30 wt % of its concentration. A cocontinuous morphology was observed between 30 and 50 wt % nylon and a phase inversion beyond 70 wt % nylon. Various models based on viscosity ratios were used to predict the region of phase inversion. Experiments were also carried out on in situ compatibilization using maleic anhydride–modified EPR (EPR‐g‐MA). In this reactive compatibilization strategy, the maleic anhydride groups of modified EPR reacted with the amino end groups of nylon. This reaction produced a graft copolymer at the blend interface, which in fact acted as the compatibilizer. The viscosity of the blend was found to increase when a few percent of modified EPR was added; at higher concentrations the viscosity leveled off, indicating a high level of interaction at the interface. Morphological investigations indicated that the size of the dispersed phase initially decreased when a few percent of the graft copolymer was added followed by a clear leveling off at higher concentration. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 252–264, 2004     

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.     

Relationship between interfacial tension and dispersed‐phase particle size in polymer blends. II. PP/PA6

Simple blends with different viscosity ratios of the components as well as compatibilized blends varying both in type and content of the compatibilizers were used to study the relation between the interfacial tension and the dispersed‐phase particle size for PP/PA6 (80/20 wt %) blends in this work. Four compatibilizing systems including poly(ethylene‐co‐methacrylic acid) ionomers, a maleic anhydride‐grafted propylene copolymer, maleic anhydride‐grafted polypropylene, and a maleic anhydride‐grafted styrene ethylene butylene copolymer were used. For blends prepared in an internal mixer, a power‐law relation was found between the capillary number and the torque ratio of the blends' components. This relation was used to estimate the interfacial tension for the compatibilized blends. The relation between the steady‐state torque of the blends as a measure of viscosity and the estimated values of interfacial tension were also investigated. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 54–63, 2003     

Properties of blends of starch and synthetic polymers containing anhydride groups. II. Effect of amylopectin to amylose ratio in starch

Corn starch with different amylopectin to amylose ratios was blended with styrene maleic anhydride copolymer (SMA) and ethylene–propylene-g-maleic anhydride copolymer (EPMA). The starch had an amylose content of approximately 0, 50, and 70%. The concentration of starch in the blend was kept constant at 60% by weight. The samples were melt blended in a corotating twin screw extruder. Scanning electron micrographs showed that the amount of starch granules remaining in the samples varied with the torque. Optical micrograph showed that starch/EPMA blends formed a cocontinuous phase in all blends irrespective of starch variety. For starch/SMA blends, the starch granules remained dispersed in the SMA phase. The torque during blending, tensile strength, water absorption, storage and loss modulus, and data on biodegradability of the blends are presented. Tensile strength and water absorption correlated well with the torque generated during blending: the higher the torque, the lower the tensile strength and the higher the water absorption. The tensile strength of blends containing SMA decreased when the humidity increased. Fractured surfaces of starch/SMA blends exhibited brittle failure; for the ductile starch/EPMA blends, shear tearing appeared to be the major failure mechanism. For blends containing EPMA, the percentage elongation increased with increased humidity. Dynamic mechanical analysis of the blends showed two sharp peaks for tan δ vs. temperature plot for starch/EPMA plots, but showed a single peak for starch/SMA blends. Starch/EPMA blends had a higher percentage of water aborption that became constant after 20 days. Using the ASTM test method D5902, the starch content in the samples was found to degrade. © 1995 John Wiley & Sons, Inc.     

Melt-neutralization of maleic anhydride grafted on high-density polyethylene compatibilizer for polyamide-6/high-density polyethylene blend: effect of neutralization level on compatibility of the blend

Blends of polyamide-6 (PA-6) and high-density polyethylene (HDPE) with blend ratios of 80/20 (wt/wt) and 20/80 (wt/wt) were studied using zinc-neutralized maleic anhydride (MAH) grafted HDPE as compatibilizers. MAH groups were hydrolyzed and neutralized with different amounts of zinc acetate dihydrate in a twin-screw extruder to produce different levels of zinc-neutralization (0, 14, 41, 69, and 95 %) at one and ten parts per hundred of resin of compatibilizer. Melt neutralization of MAH was confirmed by X-ray fluorescence, FT–IR, and rheological properties. SEM micrographs showed a large reduction in the dispersed phase size in the compatibilized blends. Tensile measurements showed improvement of tensile strength for all compatibilized blends; moreover, the elongation at break of compatibilized blends at 10 phr of compatibilizer was improved. Blending increased the crystallization temperature for the PA-6, and the addition of compatibilizer reduced the crystallization temperature slightly. A significant increase in melt viscosity of the compatibilizer was found with zinc addition and adding compatibilizer increased the viscosity of the blends. However, the addition of zinc to the compatibilizer did not change the viscosity in the PA-6-rich blends and actually led to a decrease in viscosity in the HDPE-rich blends.     

Poly(styrene-graft-ethylene oxide) as a compatibilizer in polystyrene/polyamide blends

Polystyrene (PS) blends containing a dispersed phase of either polyamide-6 (PA-6) or polyamide-12 (PA-12) were compatibilized by additions of 1, 3, or 5 wt % poly(styrene-graft-ethylene oxide). The graft copolymers were found to have a stabilizing effect on the domain sizes. Weight average radii of PA-6 domains in compression molded samples were reduced by a factor of 5 with 3 wt % graft copolymer added. The corresponding size reduction for PA-12 domains was by a factor of 3. Also, the domain sizes were more uniformly distributed in blends containing the graft copolymers. Thermal analysis of the blends revealed that compatibilization retarded the PA crystallization, with some PA crystallizing at the PS glass transition. This retarded crystallization is explained as a result of the domain size reduction and by the presence of graft copolymer at the interface. The graft copolymers had a toughening effect on the blends and the impact strength of a PS/PA-12 blend was improved by 65% by adding 3 wt % of graft copolymer. Binary blends of the PA and poly(ethylene oxide) (PEO) were investigated in a separate study to verify miscibility of the graft copolymer side chains and the PA. Hydrogen bonding between PA-6 and PEO was confirmed by IR spectroscopy and partial miscibility was indicated by melting point depressions. © 1995 John Wiley & Sons, Inc.     

The role of core/shell-microparticle dispersions in polypropylene/polyamide-6 blends

Summary Reactive blending of 70 vol.-% polypropylene (PP) and 30 vol.-% polyamide-6 (PA-6) was performed in the presence of various amounts of succinic-anhydride-functional elastomers which are immiscible with both blend components. Characteristic morphological feature of the resulting multiphase polymer blends was a continuous polypropylene matrix containing dispersed core/shell microparticles with rigid polyamide-6 core and soft elastomer shell. Accumulation of the elastomer component at the polypropylene/polyamide-6 interface and reaction of the succinic anhydride of the elastomer with the amine-endgroups of PA-6 enhanced PA-6 dispersion and proved to be the key to unusual property synergisms. In contrast to the conventional soft maleicanhydride-grafted EPM elastomer (EPM-g-MAH), the stiffer maleic-anhydride-grafted poly[styrene-b-(ethene-co-butene-1)-b-styrene] (SEBS-g-MAH) was much more efficient as blend compatibilizer and gave PP/PA-6 blends with greatly improved strength and toughness without sacrificing stiffness.     

Properties of blends of starch and synthetic polymers containing anhydride groups

Corn starch was blended with styrene maleic anhydride copolymer (SMA), ethylene-propylene-g-maleic anhydride copolymer (EPMA), and corresponding nonfunctional polystyrene and ethylene propylene copolymers. The concentration of starch in the blend was varied between 50 and 80% by weight. The torque generated during blending is reported increasing starch content for starch/SMA blends: the reverse was true for starch/EPMA blends. The torque was higher for the blends of the anhydride functional polymers compared to the blends of corresponding nonfunctional polymers. Water absorption of the blends increased with an increase in the starch content. Starch/SMA blends made at higher mixer speed or time were more water sensitive. Blends containing EPMA absorbed less water than SMA blends containing the same weight fraction of starch. Tensile strengths of blends containing functional groups were superior compared to the blends made from nonfunctional polymers. When the starch contents increased from 60 to 70%, the tensile strength remained unchanged for SMA blend but increased for EPMA blend. All samples supported the growth of microorganisms, which increased with increasing starch content. © 1994 John Wiley & Sons, Inc.