Clay locked phase morphology in the PPS/PA66/clay blends during compounding in an internal mixer

In this communication, we will demonstrate, by using poly(p-phenylene sulfide) (PPS)/polyamide66 (PA66) blends as an example, the clay can not only affect the phase morphology in immiscible polymer blends, but also frozen in the phase inversion. By adjusting the processing method, an inversed phase, where the minor component PA66 forms the continue phase and the major component PPS forms the dispersed phase, is observed for the first time. This is explained as due to the locking effects of clay layers on the phase development. The result is interesting and also very important, which provides a new way to control the phase morphology and phase inversion in immiscible polymer blends by using clay.     

Toughening and compatibilization of polyphenylene sulfide/nylon 66 blends with SEBS and maleic anhydride grafted SEBS triblock copolymers

In this study, styrene‐b‐ethylene/butylene‐b‐styrene triblock copolymer (SEBS) and maleic anhydride grafted SEBS (SEBS‐g‐MA) were used as compatibilizers for the blends of polyphenylene sulfide/nylon 66 (PPS/PA66). The mechanical properties, including impact and tensile properties and morphology of the blends, were investigated by mechanical properties measurements and scanning electron microscopy. Impact measurements indicated that the impact strength of the blends increases slowly with elastomer (SEBS and SEBS‐g‐MA) content upto 20 wt %; thereafter, it increases sharply with increasing elastomer content. The impact energy of the elastomer‐compatibilized PPS/PA66 blends exceeded that of pure nylon 66, implying that the nylon 66 can be further toughened by the incorporation of brittle PPS minor phase in the presence of SEBS or SEBS‐g‐MA. The compatibilization efficiency of SEBS‐g‐MA for nylon‐rich PPS/PA66 was found to be higher than SEBS due to the in situ forming SEBS interphase between PPS and nylon 66. The correlation between the impact property and morphology of the SEBS‐g‐MA compatibilized PPS/PA66 blends is discussed. The excellent impact strength of the nylon‐rich blends resulted from shield yielding of the matrix. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Compatibilization of ethylene/maleic anhydride/glycidyl methacrylate terpolymer for poly(phenylene sulfide)/poly(amide‐66) blends

In this article, a terpolymer of ethylene, maleic anhydride, and glycidyl methacrylate (EMG) was used to enhance the compatibilization between poly(phenylene sulfide) (PPS) and polyamide‐66 (PA66). The mechanical properties, morphology, crystalline and melting behavior, and rheology of blends were discussed. The results showed that EMG was a good compatibilizer for PPS and PA66 through chemical reaction with them. The new generated polymer could prevent the aggregation of dispersed particles and reinforce the interface bonding. In addition, it could not only act as a nucleating agent for PA66 to refine its spherulites and improve its crystallinity but also promote the apparent viscosity of blends and enhance the non‐Newtonian behavior. The results will be useful to make high performance PPS/PA66 alloy with low cost and enlarge the application scope of PPS and PA66 resin. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Preparation of conductive polyphenylene sulfide/polyamide 6/multiwalled carbon nanotube composites using the slow migration rate of multiwalled carbon nanotubes from polyphenylene sulfide to polyamide 6

Conductive polyphenylene sulfide (PPS)/polyamide 6 (PA6)/multiwalled carbon nanotube (MWCNT) composites having 10–30 wt % PA6 and 1 wt % MWCNTs are prepared by melt mixing at 300°C for 8 min using a high concentration PPS/MWCNT masterbatch approach, and the migration kinetics of MWCNTs from thermodynamically unfavored PPS to favored PA6 was investigated. The morphology of the composites was investigated by field emission scanning electron microscopy and transmission electron microscopy, showing the localization of most MWCNTs in the PPS phase and at the interface, being different from the case of direct melt mixing where non‐conductive materials were obtained with most MWCNTs found in the PA6 phase and at the interface. The electrical resistivity and morphology of the materials as a function of time were investigated, showing that the conductive materials can be prepared within a mixing time of 4–16 min because of the slow migration rate of MWCNTs from PPS toward PA6, and MWCNTs can eventually migrate into the PA6 phase after a long mixing time of 30 min. The slow migration rate of MWCNTs was attributed to the high viscosity ratio of the two phases. This article shows a good example where the migration of MWCNTs was slow enough to control and can be used to prepare conductive polymer blends. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42353.     

Effects of extensional flow on properties of polyamide‐66/poly(2,6‐dimethyl‐1,4‐phenylene oxide) blends: A study of morphology,mechanical properties,and rheology

In this study, polyamide‐66/poly(2,6‐dimethyl‐1,4‐phenylene oxide) (PA66/PPO) blends with high viscosity ratio were processed by a self‐designed triangle‐arrayed triple‐screw extruder (TTSE, which simulates extensional flow) and a commercial twin‐screw extruder (TSE), respectively. Furthermore, in order to improve the mechanical properties of the immiscible PA66/PPO blends, PPO‐grafted maleic anhydride (PPO‐g‐MA) and styrene–ethylene–butylene–styrene (SEBS) block copolymer were used. The mechanical properties, phase morphology, and rheological properties of both binary PA66/PPO blends and toughened PA66/PPO/PPO‐g‐MA blends were comprehensively investigated to compare the above mentioned two processing method. Samples processed with TTSE exhibited better mechanical properties than the TSE‐processed blends. The morphologies of the blends were examined by scanning electron microscopy, exhibiting smaller particles sizes and narrower particle size distributions, which were attributed to the significant effects of extensional flow in TTSE. The toughening mechanism of compatibilized blends was investigated through morphology analysis, dynamic mechanical, and rhelogical analysis. Thus, TTSE with an extensional effect was proved to be efficient in the blending of high viscosity ratio polymers. POLYM. ENG. SCI., 57:1090–1098, 2017. © 2016 Society of Plastics Engineers     

A change of phase morphology in poly(p-phenylene sulfide)/polyamide 66 blends induced by adding multi-walled carbon nanotubes

By adding a small amount of acid treated multi-walled carbon nanotubes (MWCNTs) into poly(p-phenylene sulfide)/polyamide 66 (60/40 w/w) blends, the morphology was found to change from sea-island to co-continuous structure. As the MWCNT content was increased, the morphology came back to sea-island but with increased domain size. It was very interesting to note that the MWCNTs were found to be selectively located in the PA66 phase, and their assembling determines the final morphology of PPS/PA66 blends. A dendritic contacted MWCNTs network was formed at low load, which leads to the formation of a co-continuous structure, and isolated MWCNT aggregates were observed at high load, which leads to the formation of sea-island morphology. Since the properties of multiphase polymeric materials are not only determined by the properties of the component polymers, but also by the morphology formed, our work indicates that the behavior of phase-separating polymer blends containing MWCNTs can be exploited to create a rich diversity of new structures and useful nanocomposites.     

Compatibilizing effect of ethylene–propylene–diene grafted maleic anhydride terpolymer on the blend of polyamide 66 and thermal liquid crystalline polymer

Polyamide 66–thermal liquid crystalline polymer (PA66/TLCP) composites containing 10 wt% TLCP was compatibilized by ethylene–propylene–diene‐grafted maleic anhydride terpolymer (MAH‐g‐EPDM). The blending was performed on a twin‐screw extrusion, followed by an injection molding. The rheological, dynamic mechanical analysis (DMA), thermal, mechanical properties, as well as the morphology and FTIR spectra, of the blends were investigated and discussed. Rheological, DMA, and FTIR spectra results showed that MAH‐g‐EPDM is an effective compatibilizer for PA66/TLCP blends. The mechanical test indicated that the tensile strength, tensile elongation, and the bending strength of the blends were improved with the increase of the content of MAH‐g‐EPDM, which implied that the blends probably have a great frictional shear force, resulting from strong adhesion at the interface between the matrix and the dispersion phase; while the bending modulus was weakened with the increase of MAH‐g‐EPDM content, which is attributed to the development of the crystalline phase of PA66 hampered by adding MAH‐g‐EPDM. POLYM. COMPOS., 27:608–613, 2006. © 2006 Society of Plastics Engineers     

Nonisothermal crystallization of polyamide 66/poly(phenylene sulfide) blends

The crystalline morphologies of isothermally and nonisothermally crystallized poly(phenylene sulfide) (PPS) and its blend with polyamide 66 (PA66) were investigated by polarized optical microscopy with a hot stage. The spherulite superstructure of PPS was greatly affected by crystallizable PA66; a Maltese cross was not clear, and the impingement between spherulites disappeared. This could be ascribed to the formation of small crystals of PA66, which filled in the PPS lamellae. The nonisothermal crystallization behavior was also measured by differential scanning calorimetry. The presence of PA66 changed the nonisothermal crystallization process of PPS. The maximum crystallization temperature of the PPS phase in the blend was higher that that of neat PPS, and this indicated that PA66 acted as a nucleus for PPS. Also, the compatibilizer poly(ethylene‐stat‐methacrylate) (EMA) was added to modify the interfacial interplay of the PA66/PPS blend system. The addition of EMA greatly influenced the nonisothermal crystallization process of the PPS phase in the blend system. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Morphology evolution of a thermotropic liquid‐crystalline polymer in a polyamide 6,6 matrix regulated by graphene

A two‐step process, thermotropic liquid‐crystalline polymer (TLCP) premixing with reduced graphene oxide (RGO) followed by blending with polyamide 6,6 (PA66), was used to prepare ternary TLCP/RGO/PA66 blends. The rheological behaviors, morphology, and mechanical properties of the blends were investigated. The results show that RGO migrated from the TLCP phase to the interface between the TLCP and PA66 phase during melt blending; this was due to a similar affinity of the RGO nanosheets to both component polymers. The dimensions of the dispersive TLCP domains were markedly reduced with the mounting RGO content; this revealed a good compatibilization effect of RGO on the immiscible polymers. The hierarchical structures of the TLCP fibrils were found in both the unfilled TLCP/PA66 blends and TLCP/RGO/PA66 blends. This supposedly resulted from the extensional and torsional action of unstable capillary flow. With the addition of RGO, the viscosities of the blends decreased further, and the fibrillation of TLCP and the mechanical performance of TLCP composites were both enhanced. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43735.     

PPS/PA66共混物的结构与性能研究

为了制备燃油汽车发动机用新型塑料进气歧管,制备了几种不同配比的PPS/PA66共混物,并对其结构与性能进行了研究。DSC分析表明,PPS/PA66共混物出现了两组分的结晶熔融峰,当共混体系中PA66的质量分数低于60%时,共混物中的PA66破坏了PPS的结晶环境,PPS的结晶度降低,其拉伸强度也随之降低;随着PA66含量的增加,共混物的结晶度提高,拉伸强度和断裂伸长率也得到了相应的提高。SEM及红外光谱分析表明,随组分含量的变化,共混体系发生了相的转变。     

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     

Study on the dynamic self‐organization of montmorillonite in two phases

Polycarbonate (PC)/acrylonitrile–butadiene–styrene (ABS) polymer alloy/montmorillonite (MMT) and nylon 6 (PA6)/ABS polymer alloy/MMT nanocomposites were prepared using the direct melt intercalation technique. Their structures were characterized by XRD and TEM. The results of TEM show that the silicate layers dispersed differently in two phases. In the PC/ABS/MMT nanocomposite, the silicate layers were self‐organized in the ABS phase, whereas in the PA6/ABS/MMT nanocomposite, the silicate layers were dispersed in both phases but mainly in the PA6 phase. Furthermore, the PC/MMT nanocomposite was melt‐mixed with pure ABS, and the changed morphology of the hybrid with the change of melt‐mixing time was characterized by XRD and TEM, to study the dynamic self‐assembly of clay layers in two phases. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1457–1462, 2004     

Effect of core‐shell morphology evolution on the rheology,crystallization, and mechanical properties of PA6/EPDM‐g‐MA/HDPE ternary blend

In this article, polyamide 6 (PA6), maleic anhydride grafted ethylene‐propylene‐diene monomer (EPDM‐g‐MA), high‐density polyethylene (HDPE) were simultaneously added into an internal mixer to melt‐mixing for different periods. The relationship between morphology and rheological behaviors, crystallization, mechanical properties of PA6/EPDM‐g‐MA/HDPE blends were studied. The phase morphology observation revealed that PA6/EPDM‐g‐MA/HDPE (70/15/15 wt %) blend is constituted from PA6 matrix in which is dispersed core‐shell droplets of HDPE core encapsulated by EPDM‐g‐MA phase and indicated that the mixing time played a crucial role on the evolution of the core‐shell morphology. Rheological measurement manifested that the complex viscosity and storage modulus of ternary blends were notable higher than the pure polymer blends and binary blends which ascribed different phase morphology. Moreover, the maximum notched impact strength of PA6/EPDM‐g‐MA/HDPE blend was 80.7 KJ/m² and this value was 10–11 times higher than that of pure PA6. Particularly, differential scanning calorimetry results indicated that the bulk crystallization temperature of HDPE (114.6°C) was partly weakened and a new crystallization peak appeared at a lower temperature of around 102.2°C as a result of co‐crystal of HDPE and EPDM‐g‐MA. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

A quantitative estimation of the extent of compatibilization in heterogeneous polymer blends using their heat capacity increment at the glass transition

In this paper a new method based on the determination of heat capacity increment at the glass transition (ΔCp) is presented to quantify the effectiveness of compatibilizers for immiscible polymer blends. In order to show the validity of the method, two immiscible blends, polypropylene–poly(ethylene terephthalate) (PP–PET) and PP–polyamide‐6,6 (PP–PA66), and two compatibilizers, N, N‐dihydroxyethyl monomaleic amide–grafted PP (g–PP) alone and together with a phenolic resin (PR), were investigated. Scanning electron microscopy (SEM) observations prove that the two compatibilizer systems are both effective for compatibilizing the blends, and the combined use of g–PP and PR is more effective than g–PP alone. Modulated‐temperature differential‐scanning calorimetry (M‐TDSC) determinations reveal that the ΔCp varies with the extent of compatibilization. For the uncompatibilized blends, the ΔCp for the PET component in PP–PET or for the PA66 component in PP–PA66 was found to be almost unchanged. After compatibilization these quantities become smaller. Also, the combined use of g–PP and PR results in the smallest ΔCp values for both blends. This ΔCp change with different compatibilizers is in very good agreement with the corresponding morphological variation observed by SEM. Thus, ΔCp can be taken as a new parameter for quantifying the extent of compatibilization, since it is a direct measure of interfacial content. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 2868–2876, 1999     

Effect of clay addition on the morphology and thermal behavior of polyamide 6

The nanostructure, morphology, and thermal properties of polyamide 6 (PA6)/clay nanocomposites were studied with X‐ray scattering, differential scanning calorimetry (DSC), and transmission electron microscopy (TEM). The wide‐angle X‐ray diffraction (WAXD) and TEM results indicate that the nanoclay platelets were exfoliated throughout the PA6 matrix. The crystallization behavior of PA6 was significantly influenced by the addition of clay to the polymer matrix. A clay‐induced crystal transformation from the α phase to the γ phase for PA6 was confirmed by WAXD and DSC; that is, the formation of γ‐form crystals was strongly enhanced by the presence of clay. With various clay concentrations, the degree of crystallinity and crystalline morphology (e.g., spherulite size, lamellar thickness, and long period) of PA6 and the nanocomposites changed dramatically, as evidenced by TEM and small‐angle X‐ray scattering results. The thermal behavior of the nanocomposites was investigated with DSC and compared with that of neat PA6. The possible origins of a new clay‐induced endothermic peak at high temperature are discussed, and a model is proposed to explain the complex melting behavior of the PA6/clay nanocomposites. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1191–1199, 2007     

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

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

Polyamide 66/Clay Nanocomposites via Melt Intercalation

Polyamide 66/clay nanocomposites (PA66CN) were prepared via a melt compounding method using a new kind of organophilic clay, which was obtained through co‐intercalation of epoxy resin and quaternary ammonium into Na‐montmorillonite. The dispersion effect of silicate layers in the matrix was studied by means of XRD and TEM. The silicate layers were dispersed homogeneously and nearly exfoliated in the matrix as a result of the strong interaction between epoxy groups and PA66. The mechanical properties and heat distortion temperature (HDT) of PA66CN increased dramatically. The notched Izod impact strength of PA66CN was 50% higher than that of PA66 when the clay loading was 5 wt.‐%. Even at 10 wt.‐% clay content, the impact strength was still higher than that of PA66. The finely dispersed silicate layers and the strong interaction between silicate layers and the matrix reduced the water absorption, at 10 wt.‐% clay content; PA66CN only absorbs 60% water compared with PA66. The addition of silicate layers changed the crystal structure in PA66CN.     

Effect of maleic anhydride grafted polybutadiene on the compatibility of polyamide 66/acrylonitrile‐butadiene‐styrene copolymer blend

The addition of maleic anhydride grafted polybutadiene (PB‐g‐MAH) can greatly improve the compatibility of polyamide 66 (PA66)/acrylonitrile‐butadiene‐styrene copolymer (ABS) blends. Unlike the commonly used compatibilizers in polyamide/ABS blends, PB‐g‐MAH is compatible with the ABS particles' core phase polybutadiene (PB), rather than the shell styrene‐acrylonitrile (SAN). The compatibility and interaction of the components in the blends were characterized by Fourier transform‐infrared spectra (FTIR), Molau tests, melt flow index (MFI), dynamic mechanical analyses (DMA), and scanning electron microscopic (SEM) observations. The results show that PB‐g‐MAH can react with the amino end groups in PA66 while entangle with the PB phase in ABS. In this way, the compatibilizer anchors at the interface of PA66/ABS blend. The morphology study of the fracture sections before and after tensile test reveals that the ABS particles were dispersed uniformly in the PA66 matrix and the interfacial adhesion between PA66 and ABS was increased significantly. The mechanical properties of the blends thus were enhanced with the improving of the compatibility. POLYM. ENG. SCI., 2012. © 2011 Society of Plastics Engineers     

Effect of blend ratio and compatibilisation on the electrical and dielectric properties of nylon copolymer (6, 66)/EPDM rubber blends

In this work, morphological, electrical, and dielectric performance of nylon copolymer (PA6, 66)/ethylene propylene diene rubber (EPDM) blends were systematically studied with reference to blend ratio and compatibilisation. As the concentration of PA6, 66 and the percentage of compatibiliser in the blend increases the resistivity values decreases. The existence of two phases, PA6, 66 and EPDM with different conductivity and interfacial polarization are responsible for the increase in the dielectric properties of the blends. Compatibilisation of the blends improved the dielectric constant of the blend system. Addition of 2.5% of compatibiliser gave the highest value of dielectric constant. At a high concentration of EPM‐g‐MA, the polarity of the compatibilised blends was found to be increased, which resulted in the substantial increase in the value of loss and dissipation factor. The dielectric values of the blends were correlated with blend phase morphology. Finally the experimental data was compared with various theoretical predications. POLYM. ENG. SCI., 59:2195–2201, 2019. © 2019 Society of Plastics Engineers     

Influence of morphology on positive temperature coefficient effect for conductive polymer composites with carbon black dispersed at interface

Selective localization of carbon black (CB) at the interface of polymer blends was achieved by the method that EBA‐g‐MAH was first reacted with CB, and then blended with poly(ethylene‐co‐butyl acrylate)/nylon6 (EBA/PA6). In CB‐filled EBA/PA6 blends, EBA and PA6 phases formed cocontinuous morphology and CB was localized in PA6 phase. The percolation threshold was 5 wt%. A single PTC (positive temperature coefficient) effect was observed in this composite. The appearance of PTC effect was originated from the thermal expansion of EBA phase. In the EBA‐g‐MAH filled EBA/PA6 blends, TEM results showed that CB particles were induced by EBA‐g‐MAH to localize at the interface, resulting that the percolation threshold was much lower than that of EBA/PA6/CB. Influence of morphology on PTC effect of EBA/PA6/EBA‐g‐MAH/CB composites was studied. In the composites with sea‐island morphology, the conductive network was fabricated by dispersed phase and CB at the interface. Thermal expansion of matrix interrupted the contact of dispersed phases and conductive network formed by CB particles at the interface, resulting in the double PTC effect. The composites with co‐continuous morphology exhibited single PTC effect due to the fact that conductive network was only fabricated by CB localized at the interface. POLYM. ENG. SCI., 53:2640–2649, 2013. © 2013 Society of Plastics Engineers