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     

Effect of dispersed phase on the morphology of in situ microfibrils and the viscoelastic properties of its composite via direct extrusion

A triangle arrayed triple‐screw extruder was used to prepare in situ polypropylene (PP) microfibrillar composites (MFCs) by direct extrusion, in which polyamide 6,6 (PA66) and poly(butylene terephthalate) (PBT) were used as dispersed phases while PP as matrix phase. The morphological evolution of the dispersed phase were investigated by SEM through taking samples along the extruder from different positions. The results showed that the fibrillating mechanism of PA66 was entirely different from that of PBT. Dynamic oscillatory shear rheological properties were used to analyze the effect of different types of in situ microfibrils on the rheological properties of MFCs. The obtained results showed that the storage modulus and complex viscosity of both PP/PA66 and PP/PBT MFCs were improved with increasing fibrillar aspect ratios. The loss tangent tan δ at low frequencies decreased with the increase of fibrillar aspect ratio. Moreover, the gel point concentration of PP/PA66 composite was lower than that of PP/PBT composite. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46286.     

In‐line measurements of the morphological parameters of PP/PA6 blends during extrusion in the transient mode

The real‐time measurement of the morphology of immiscible polymer blends based on polypropylene (PP) and polyamide 6 (PA6) was performed during melt blending in a twin‐screw extruder. The disperse phase particle size and concentration were obtained in‐line with an optical device placed at the die exit. To validate the response of the optical device, its detector was calibrated in advance in a bench using ceramic particles of well‐controlled size dispersed in water. The optical device was able to measure the changes in particle size and concentration and the data enabled the calculation of the particle extinction cross section. Melt blending experiments in the extruder were performed in a transient mode, where a small amount of the material was added as a pulse to the main melt flow. The pulses containing pellets of the PA6 and polypropylene grafted with acrylic acid (PP‐g‐AA) were added to the PP flow stream in different amounts. The detector's response increased with increasing concentrations in the PA6 and PP‐g‐AA. The disperse phase particle size decreased concomitantly because of the compatibilizing effect of the PP‐g‐AA on the PP/PA6 immiscible blend. That observation confirmed that the detector's response was directly related to the disperse phase particle size. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

Pan‐milling mixing – a novel approach to forming polymer blends and controlling their morphology

A novel technique (pan‐milling mixing) was developed to control the morphology and thus enhance the mechanical properties of polypropylene/polyamide 6 (PP/PA6) systems. Through pan‐milling at ambient temperature, PP/PA6 pellets of particle size 2–4 mm can be effectively pulverized to well‐mixed micrometre fine powders in the solid state. During pan‐milling of mixtures of PP and PA6, the polymer molecules undergo chain scission and form copolymers that compatibilize the two polymers in situ. By press moulding the finely mixed PP/PA6 powder obtained at a temperature between the melting points of PA6 and PP (for example 200 °C), a blend can be obtained in which the PA6 powder, retained throughout the process in the solid state, is well dispersed in the PP matrix. The mechanical properties of the system are much better than that of PP/PA6 blends prepared by common twin screw extrusion mixing and injection moulding. Tensile strengths of the fine PA6 particle filled PP/PA6 (70/30) blend is 29.3 MPa, which is 6.1 MPa higher than that of a conventionally prepared PP/PA6 blend. The Izod notched impact strength of a fine PA6 particle‐filled PP/PA6 (70/30) blend is 6.34 kJ m^?2, which is 1.72 kJ m^?2 higher than that of a conventionally prepared PP/PA6 blend. Morphological analysis shows that the domain size of PA6 in the system is much smaller than that of the PP/PA6 blend, and can be controlled by the processing conditions such as temperature. © 2001 Society of Chemical Industry     

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     

From polymer blends to in situ polymer/polymer composites: Morphology control and mechanical properties

In situ polymer/polymer short fiber composites were generated by a two‐step process. In the first step, a polyamide (PA) dispersed phase is blended with a polypropylene (PP) matrix in a twin‐screw extruder at a temperature at which both polymers are in molten state. The extrudate was then stretched at the die exit to generate long and thin fibers of PA in the PP matrix well oriented in the direction of flow. Adhesion between the phases was promoted by addition of PP grafted with maleic anhydride (PP‐g‐MA). During the second step, the chopped extrudates were molded by injection or compression molding at a temperature at which PA in the form of fibers is in the solid state and the PP matrix is molten. The control of the formation of such ultrafine fibers was obtained by quantitative analyses for the deformation of the minor PA‐phase during twin‐screw extrusion and stretching at the exit of the die that involve both shear and extensional flows. Morphology and mechanical properties of such polymer/polymer composites were compared to equivalent blends with dispersed spherical particles‐type morphology prepared in a batch mixer device.     

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     

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     

Mechanical properties of polypropylene/polyamide 6 blends: Effect of manufacturing processes and compatibilization

The properties of polypropylene (PP)/polyamide 6 (PA) blends, obtained by the following two different blending methods, were investigated. Blends of PP/PA and PP/PA/maleic anhydride have been prepared using a twin screw extruder and a fiber cutting, flying and mixing apparatus that directly commingles PP fiber and PA fiber. The properties measured include rheological properties by means of a capillary rheometer, morphologies by scanning electron microscopy, and mechanical properties by a universal testing machine and a high rate impact tester. In the presence of compatibilizer, a marked dispersibility of the polymer blends of PP and PA was observed, and mechanical properties were found to increase as a result of improvement of the interfacial adhesion and the dispersibility. The properties of PP/PA blends manufactured by two different pieces of equipment were shown to be similar in the case of melting both resins. But in particular, superior impact properties were obtained in blends not melting PA fibers as a dispersed phase rather than blends using maleic anhydride grafted polypropylene (PP-g-MA) as a compatibilizer.     

Influences of component ratio of minor phases and charge sequence on the morphology and mechanical properties of PP/PS/PA6 ternary blends

In this study, influences of both component ratio of minor phases and charge sequence on the morphology and mechanical performance in typical ternary blends, polypropylene (PP)/polystyrene (PS)/polyamide-6 (PA6), have been studied. Reactive compatibilization of the blends has been carried out using multi-monomer melt grafted PP with anhydride groups and styrene segments. For uncompatibilized blends, scanning electron microscope (SEM) and selective solvent extraction showed that the blends presented a core–shell morphology with PS as shell and PA6 as core in the PP matrix, in spite of the component ratio and charge sequence. The shell thickened and droplet size decreased with increasing the PS/PA6 component ratio. While for compatibilized blends, the addition of compatibilizers resulted in a significant reduction of the dispersed droplet size and the phase structure of the dispersed phases was greatly dependent on the charge sequence. When the blending of PA6, g-PP, and PP are preceded, the encapsulation structure reversed into the structure of PS phase encapsulated by PA6 phase, which led to better tensile and flexural strength of the blends.     

有机蒙脱土对PA6/PP合金体系的作用机制及其对材料性能的影响

研究了有机蒙脱土对PA6/PP合金体系的作用机制及其对材料性能的影响。结果表明,OMMT的添加可以提高体系的拉伸强度、弯曲强度和弯曲模量,但冲击强度会有某种程度的下降;OMMT主要分散在PA6连续相中,且当其添加量质量份数低于5%时,可以在PA6相中实现较充分的剥离;OMMT对PA6/PP合金体系有着显著的增容作用,这可能和片层对PP分散相凝聚时的阻隔,以及片层所起到的类似接枝物的增容作用有关;OMMT在PA6基体中被充分剥离后,将有利于使复合体系的拉伸强度、弯曲强度得到提高,但OMMT片层及和片层有关的类似接枝物的存在,将束缚并限制界面层附近PP相的屈服,而使材料冲击韧性下降。     

Effect of blending sequence on the morphology and properties of polyamide 6/EPDM‐g‐MA/epoxy blends

The ternary blends of polyamide 6/maleated ethylene‐propylene‐diene rubber/epoxy (PA6/EPDM‐g‐MA/EP) were prepared by a twin‐screw extruder with four different blending sequences. With the variation of blending sequence, the ternary blends presented distinct morphology and mechanical properties because of different interactions induced by various reactive orders. The addition of epoxy could increase the viscosity of the PA6 matrix, but a considerably larger size of the dispersed rubber phase was observed while first preblending PA6 with epoxy followed by blending a premix of PA6/EP with EDPM‐g‐MA, which was attested by rheological behaviors and SEM observations. It was probably ascribed to the fact that the great increase of the interfacial tension between the matrix and rubber phase aroused a great coalescence of rubber particles. The presence of epoxy in the rubber phase reduced the rubber's ability to cavitate so that the toughening efficiency of the EPDM‐g‐MA was decreased. The results of mechanical testing revealed that the optimum blending sequence to achieve balanced mechanical properties is blending PA6, EPDM‐g‐MA, and epoxy simultaneously in which the detrimental reactions might be effectively suppressed. In addition, thermal properties were investigated by TG and DSC, and the results showed that there was no distinct difference. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Study on the microstructure and properties of bromobutyl rubber (BIIR)/polyamide‐12 (PA12) thermoplastic vulcanizates (TPVs)

In this study, polyamide‐12 (PA12)/brominated isobutylene‐isoprene (BIIR) TPVs with good mechanical properties and low gas permeability were prepared by dynamic vulcanization in a twin‐screw extruder. The effects of three kinds of compatibilizers on the microstructure and properties of BIIR/PA12 TPV were studied. The compatibility between BIIR and PA12 was improved when maleated hydrocarbon polymeric compatibilizer is added. The reaction between maleic anhydride and amine in polyamide leads to the in situ formation of hydrocarbon polymer grafted polyamide which subsequently can be used to lower the interfacial tension between BIIR and polyamide. The compatibilizing effect of maleic anhydride modified polypropylene (PP‐g‐MAH) on BIIR/PA12 blends is the best among these compatibilizers because the surface energy of PP‐g‐MAH is very close to that of BIIR. The dispersed rubber phase of the blend compatibilized by PP‐g‐MAH shows the smallest size and more uniform size distribution, and the resulting TPVs show the best mechanical properties. The effects of fillers on the properties of BIIR/PA12 TPV were also investigated. The size of the BIIR phase increases with the increase in the content of CaCO₃. The modulus and tensile strength of TPVs increased with the increase in the content of CaCO₃ because of the reinforcing effect of CaCO₃ on TPVs. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43043.     

Novel milling route for controlling structure and properties in SBS elastomer blends containing dispersed PA6 and PP particles

Abstract

A novel technique to optimise the morphology and thus to enhance the mechanical properties of styrene/butadiene/styrene (SBS) triblock copolymer blends containing dispersed polyamide 6 (PA6)/polypropylene (PP) is reported. The SBS-PA6-PP composite was prepared by blending SBS with PA6-PP ultrafine powder, which was obtained by pulverising PA6 and PP in a pan mill at ambient temperature. The mechanical properties of the composite were determined and the variations of the phase structure of the composites prepared at different processing temperatures were studied by TEM. The thermooxidative stabilities of the composites were tested by thermogrivimetry (TG). The results indicate that preparing a PA6-PP ultrafine powder by the solid state mechanochemical process can improve the compatibility of PA6 with PP and SBS and accelerate the dispersion of PP and PA6 as well as their combination with SBS at the phase interface. The tensile strength of the composite can be increased greatly with an ultrafine powder content of 4-8%, while the elongation at break remains approximately constant. The variation of processing temperature causes a change in the phase structure of the plastics, which has a great effect on the properties of the composite. When the processing is carried out at the melting temperature of the PP, the PP particles combine to form a fibrillar structure that can increase the tensile strength of the matrix from 12·7 to 25 0 MPa. The temperature at which a 10% weight loss occurs in the composite increases from 396·0 to 412·7°C and the temperature of maximum weight loss increases from 454·3 to 479·3°C with an ultrafine powder content of 4%. PRC/1747     

Morphology development of in situ compatibilized semicrystalline polymer blends in a co-rotating twin-screw extruder

This paper concerns the morphology development of in situ compatibilized semicrystalline polymer blends in a co-rotating, intermeshing twin-screw extruder, using polypropylene (PP) and polyamide 6 (PA-6) blends as model systems. The morphology of in situ compatibilized blends develops much faster that of mechanical ones. The size of the dispersed phase (PA-6) undergoes a 10⁴ fold reduction from a few millimeters to sub-micron during its phase transition from solid pellets to a viscoelastic fluid. The final morphology is reached as soon as the phase transition is completed, which usually requires only a small fraction of the screw length in a co-rotating twin screw extruder. Screw profiles and processing conditions (screw speed, throughput and barrel temperature) control the PA-6's melting location and/or rate, but do not have significant impact on the ultimate morphology and mechanical properties of in situ compatibilized blends. The finding that morphology of PP/PA-6 reactive blend develops rapidly makes it possible to produce compatibilized PP/PA-6 blends by the so-called one-step reactive extrusion. It integrates the traditionally separated free radical grafting of maleic anhydride onto PP and the compatibilization of PP/PA-6 into a single extrusion step.     

Synergetic toughness and morphology of poly(propylene)/nylon 11/maleated ethylene‐propylene diene copolymer blends

Polypropylene (PP)/nylon 11/maleated ethylene‐propylene‐diene rubber (EPDM‐g‐MAH) ternary polymer blends were prepared via melt blending in a corotating twin‐screw extruder. The effect of nylon 11 and EPDM‐g‐MAH on the phase morphology and mechanical properties was investigated. Scanning electron microscopy observation revealed that there was apparent phase separation for PP/EPDM‐g‐MAH binary blends at the level of 10 wt % maleated elastomer. For the PP/nylon 11/EPDM‐g‐MAH ternary blends, the dispersed phase morphology of the maleated elastomer was hardly affected by the addition of nylon 11, whereas the reduced dispersed phase domains of nylon 11 were observed with the increasing maleated elastomer loading. Furthermore, a core‐shell structure, in which nylon 11 as a rigid core was surrounded by a soft EPDM‐g‐MAH shell, was formed in the case of 10 wt % nylon 11 and higher EPDM‐g‐MAH concentration. In general, the results of mechanical property measurement showed that the ternary blends exhibited inferior tensile strength in comparison with the PP matrix, but superior toughness. Especially low‐temperature impact strength was obtained. The toughening mechanism was discussed with reference to the phase morphology. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

PP/PA6共混比例对其水辅助注塑管件性能及微观形态的影响

以聚丙烯 (PP)为基材,聚酰胺6(PA6)为分散相,制备了4种共混比例的PP/PA6复合材料,考察了共混比例对其水辅助注射成型技术（WAIM）管件拉伸强度及微观形态的影响。结果表明,试样拉伸强度随PA6含量增加先减小后增大;近模壁层和近水层的PA6分散相为大长厚比的长条状或长片状,中间层分散相为椭球状,且随PA6含量增加各层分散相有聚集长大的趋势;管件近模壁层和近水层的晶粒小而密且沿流动方向排列,而中间层晶粒相对更粗大;PP只形成了一种晶型,PA6形成了2种晶型;近水层和近模壁层PP结晶度高于中间层;PA6随其含量增加其结晶度有增大的趋势,且近模壁层结晶度较高。     

Effect of compatibilizer on the dispersion of untreated silica in a polypropylene matrix

BACKGROUND: A new processing method for polypropylene–untreated precipitated silica (PP/SiO₂) composites based on the incorporation of a second polymer phase of polyamide 6 (PA6) is presented and compared with a more classic one making use of compatibilizers: glycerol monostearate (GMS), ethylene acrylic acid ionomer (IAAZE) and maleic anhydride grafted polypropylene (MA‐graft‐PP). The effects of processing methods and conditions on the microstructure and properties of PP/SiO₂ composites prepared by melt compounding are investigated with a view to reduce the size of aggregates of silica from the micrometre to the nanometre scale and to improve the link between filler and matrix. RESULTS: On the one hand, the presence of GMS and IAAZE compatibilizers significantly improves the dispersion of the silica particles. On the other hand, when using a PA6 second phase, the SiO₂ particles are dispersed in PA6 nodules. Within these nodules, SiO₂ appears dispersed at the nanoscale but with larger particles (‘aggregates’) of about 200 nm. Significant improvements in tensile strength and modulus are obtained using MA‐graft‐PP compatibilizer. An increase in impact strength is observed in the case of GMS compatibilizer. Thermal parameters indicate also that silica plays the role of nucleation agent for PP matrix. All improvements (tensile strength, modulus and impact strength) increase with the addition of compatibilized PA6 second phase. CONCLUSION: By the incorporation of masterbatch of silica in PA6 as a second polymer polar phase, a successful new production method for PP/SiO₂ nanocomposites has been developed. Interestingly, this method does not require any (expensive) pre‐treatment of the silica. Copyright © 2007 Society of Chemical Industry     

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     

Blending PP with PA6 industrial wastes: Effect of the composition and the compatibilization

Blending polypropylene to recycled PA6 industrial wastes at different compositions, with and without compatibilizer PPgMA was produced in a corotating twin screw extruder where, polypropylene acts as the polymer matrix and polyamide as the dispersed phase. Several techniques were used to investigate the morphology, thermal, viscoelastic and tensile properties of these blend. Binary PP/PA6 blends showed the presence of PA6 particles dispersed in the PP continuous phase and exhibited a coarse morphology. Increasing PA6 contents in the blend increased their crystallinity and their size and improved the tensile properties at weak deformation. In addition to compatibilizer PPgMA, the morphology shows lower diameters and a decrease in size of the dispersed PA6 particles. The interfacial adhesion was also improved, as a result of the creation of an interphase that was formed by the interaction between the formed PPgPA6 copolymer in situ and both phases. This interphase induced an improvement in tensile properties. The PPgPA6 copolymer generated by the interphase was identified with DMA analysis thanks to an additional transition in loss modulus curves. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008