Effect of in situ synthesized macroactivator on morphology of PA6/PS blends via successive polymerization

In situ polymerization and in situ compatibilization was adopted for preparation of ternary PA6/PS‐g‐PA6/PS blends by means of successive polymerization of styrene, with TMI and ε‐caprolactam, via free radical copolymerization and anionic ring‐opening polymerization, respectively. Copolymer poly(St‐g‐TMI), the chain of which bears isocyanate (? NCO), acts as a macroactivator to initiate PA6 chain growth from the PS chain and graft copolymer of PS‐g‐PA6 and pure PA6 form, simultaneously. The effect of the macroactivator poly(St‐g‐TMI) on the phase morphology was investigated in detail, using scanning electron microscopy. In case of blends with higher content of PS‐g‐PA6 copolymer, copolymer nanoparticles coexisting with the PS formed the matrix, in which PA6 microspheres were dispersed evenly as minor phase. The content of the compositions (homopolystyrene, homopolyamide 6, and PS‐g‐PA6) of the blends were determined by selective solvent extraction technique. The mechanical properties of PA6/PS‐g‐PA6/PS blends were better than that of PA6/PS blends. Especially for the blends T10 with lower PS‐g‐PA6 copolymer content, both the flexural strength and flexural modulus showed significantly improving because of the improved interfacial adhesion between PS and PA6. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Compatibilizing efficiency of copolymer precursors for immiscible polymer blends

An anhydride‐terminated polystyrene (PS‐b‐Anh) as a block copolymer precursor and a copolymer (PS‐co‐TMI) of styrene (St) and 3‐isopropenyl‐α,α‐dimethylbenzene isocyanate (TMI) as a graft copolymer precursor are chosen to investigate the effect of the type of the copolymer precursor on its compatibilizing and stabilizing efficiency for polymer blends. Results show that during the melt blending of the PS and PA6, the addition of PS‐b‐Anh dramatically decreases the size of the dispersed phase domains, irrespective of its molecular weight. This indicates that a diblock copolymer PS‐block‐PA6 (PS‐b‐PA6) is formed by a reaction between the terminal anhydride moiety of the PS‐b‐Anh and the terminal amine group of the PA6. When PS/PA6 (30/70) blends are annealed at 230°C for 15 min, their morphologies are much more stable in the presence of the PS‐b‐Anh block copolymer precursor than in the presence of the PS‐co‐TMI graft copolymer precursor. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Formation of bead‐free and core–shell superfine electrospinning fibers under the assistance of another polymer and an interfacial compatibilizer

This work presents a new way of preparing bead‐free and core–shell superfine polymer electrospinning fibers under the assistance of another polymer and an interfacial compatibilizer. For the electrospinning of polystyrene (PS)/CHCl₃ solution, the bead‐free fiber cannot be obtained until the PS concentration is above 0.25 g/mL but its average diameter is above 10 μm. Using polyamide 6 (PA6) as an additive, the critical concentration capable of forming bead‐free fiber greatly decreased and core–shell fibers with PA6 as the core and PS as the shell were obtained due to the driving effect of high spinability of PA6. The introduction of a copolymer (PS‐co‐TMI) of styrene (St) and 3‐isopropenyl‐α,α‐dimethylbenzene isocyanate (TMI) can react with amine of PA6 to form the copolymer of PS and PA6 as an interfacial compatibilizer. As a result, it can further enhance the dispersion and deformation of minor component PA6 into uniform microfiber core, and drive PS to uniformly cover the surface of PA6 fibers, and finally form bead‐free and core–shell superfine fibers. POLYM. ENG. SCI., 59:1437–1444 2019. © 2019 Society of Plastics Engineers     

In situ control of co‐continuous phase morphology for PS/PS‐co‐TMI/PA6 blend

The emulsification efficiency of PS‐co‐TMI, a copolymer polymerized by styrene and 3‐isopropenyl‐α,α‐dimethylbenzene isocyanate (TMI), for polystyrene (PS)/polyamide 6 (PA6) blend was studied. During the mixing process, an effective emulsifier PS‐g‐PA6 was generated, which was demonstrated by differential scanning calorimetry (DSC) and fourier transform infrared spectroscopy. PS‐g‐PA6 generated by PS‐co‐TMI with high TMI content was found to contain some unreacted isocyanate active groups which reduced using efficiency of PS‐co‐TMI. Irrespective of TMI content in PS‐co‐TMI, the dosage of PS‐co‐TMI reached 20 wt %, unreacted PS‐co‐TMI was detected. These results indicated that reactive emulsification limits for both active groups' content and reactive precursors' dosage. After the rational addition of PS‐co‐TMI into PS/PA6 system, phase sizes of co‐continuous structure were reduced conspicuously. However, co‐continuous structure was evolved into matrix‐dispersed structure while the dosage of PS‐co‐TMI reached 20 wt %. Emulsification efficiencies of PS‐co‐TMI with different TMI contents, 2.2, 4.1, and 7.5 wt %, were compared. The results revealed PS‐co‐TMI with 2.2 wt % TMI content had the highest reactive emulsification efficiency because of the block‐copolymer‐inclined emulsifier generated in the mixing process. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 39972.     

Tracer‐compatibilizer: Synthesis and applications in polymer blending processes

This article reports on a route to synthesizing fluorescent labeled graft copolymers, on the one hand; and on a concept of tracer‐compatibilizer for facile build‐up of emulsification curves of polymer blends, on the other hand. For these purposes, blends composed of polystyrene (PS) and polyamide 6 (PA6) are chosen. The synthesis of the corresponding tracer‐compatibilizer consists of three steps: (1) copolymerization of styrene with 3‐isopropenyl‐α,α'‐dimethybenzyl isocyanate (TMI); (2) conversion of a fraction of the isocyanate moieties of the resulting copolymer into anthracene ones upon reacting with 9‐(methylamino‐methyl)anthracene (MAMA); and (3) polymerization of ε‐caprolactam (CL) from the remaining isocyanate moieties. The resulting fluorescent labeled graft copolymer, denoted as PS‐g‐PA6‐Ant, is used to build up emulsification curves of PS/PA6 blends in a twin screw extruder (TSE), showing great usefulness of the concept of tracer‐compatibilizer. POLYM. ENG. SCI. 2012. © 2011 Society of Plastics Engineers     

Morphology and properties of PET/PA‐6/SiO2 ternary composites

A kind of hydrophilic nano‐SiO₂ was applied to poly(ethylene terephthalate)/polyamide‐6 (PA‐6) blends. Melt‐blended composites were prepared at various component ratios and different nano‐SiO₂ levels. Mechanical, morphological, dynamic mechanical, and thermal tests were carried out to characterize the properties, morphology, and compatibilization of the composites. Increased impact strength, tensile strength, and modulus were observed by adding nano‐SiO₂ particles in the blends. The nano‐SiO₂ particles were found to be preferentially dispersed in PA‐6, resulting in an increase of glass transition temperature and crystallization of PA‐6. The mechanism of morphology and properties changes was discussed based on the selective dispersion of nano‐SiO₂ particles in the blends. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 2288–2296, 2007     

Reactive blending of poly (dimethylsiloxane) with nylon 6 and poly (styrene):Effect of reactivity on morphology

Reactive compatibilization was used to control and stabilize 20–30wt% poly(dimethylsioxane) (PDMS) dispersions in nylon 6 (PA) and poly(styrene) (PS), respectively. The effect of the type of reation (amine (NH₂)/anhydride (An), NH₂/ epoxy(E) and carboxylic acid (COOH)/E) on the morphology was studied with electron microscopy. PS and PDMS have mutual solvents thus it was possible to use gel permeation chromatography (GPC) to determine the concentration of block copolymer in PS/PDMS blends. Reactive blending of PA6 with difunctional PDMS‐(AN)₂ did not decrease the PDMS particle size compared to the non‐reactive blend (～10μm). Particle size decreaeased significantly to about 0.5 μm when PA6 was blended with a PDMS containing about 4 random An groups along the chain. For the PS/PDMS blends, GPC revealed that the NH₂/An reaction formed about 3% block copolymer and produced stable PDMS particles ～ 0.4 μm. No reaction was detected for the PS‐NH₂/PDMS‐E blend and the morphology was coarse and unstable. Also, PS‐NH₂/PDMS‐An reactivity was lower compared to other systems such as PS/ poly (isoprene) and PS/poly(methaacrylte) using the same reaction. This was attributed to the relatively thinner PS/PDMS interface dueto the high PS/PDMs immiscibility.     

Synthesis,characterization, and properties of polystyrene/SiO2 hybrid materials via sol–gel process

Isocyanate‐functionalized polystyrene (P(St‐co‐TMI)) was successfully synthesized by solution free radical polymerization, which was then used to react with (3‐aminopropyl) triethoxysilane (APTES) to prepare a precursor of polystyrene/inorganic composites (PS/SiO₂). To obtain PS/SiO₂ composites with chemical bond, the precursor was mixed with triethoxysilane (TEOS) under the sol–gel reaction condition. The chemical bond between the PS and SiO₂ particles made the crosslink network more stable and avoided aggregation compared with the physical connection and barely mechanical mixing. The Fourier transform infrared (FT‐IR) results indicate that the isocyanate group ( NCO) was completely reacted with APTES. The field‐emission scanning electron microscopy results show that the morphology of composites and the distribution of the particles, which exhibit good compatibility between organic and inorganic phases, and the inorganic particles show good spatial uniformity. The differential scanning calorimetry shows that the glass transition temperature (T_g) of the PS/SiO₂ composites was shifted to high temperature when the amount of APTES increased. The thermal degradation temperature of the PS/SiO₂ composites increases with the increasing of APTES content. Master curves at 200°C are constructed for the storage and loss modulus as well as complex viscosity. POLYM. COMPOS. 36:482–488, 2015. © 2014 Society of Plastics Engineers     

Phase morphology evolution and compatibilization of immiscible polyamide 6/polystyrene blends using nano‐montmorillonite

Nanocomposites of organic nano‐montmorillonite (nano‐OMMT)‐filled immiscible polyamide 6 (PA6)/polystyrene (PS) blends were prepared by three different processing methods. Masterbatch M1 of OMMT/PA6 and masterbatch M2 of OMMT/PS were prepared as separate masterbatchs by melt mixing with PA6 or PS, and then either mixed together or each mixed individually with appropriate amounts of PS or PA6, respectively. The effects of nano‐OMMT content and processing method on the structure, phase morphology, and mechanical properties of the PA6/PS/OMMT nanocomposites were investigated by X‐ray diffraction, transmission electron microscopy, scanning electron microscopy, and mechanical properties tests. The results showed that the nano‐OMMT by M1 and M2 masterbatches dispersed primarily as exfoliated platelets in the PA6 matrix in the final composites regardless of the method of preparation. A drastic decrease of dispersed PS phase size and a very homogeneous size distribution were observed with the addition of nano‐OMMT. The PA6/PS/OMMT nanocomposites prepared from the M2 displayed the smallest dispersed PS phase size and best distribution of OMMT. The improvement of the mechanical properties of the PA6/PS/OMMT nanocomposites was attributed to the enhanced compatibilization of the immiscible PA6/PS blends by using nano‐OMMT. POLYM. ENG. SCI., 2017. © 2017 Society of Plastics Engineers     

Relationship between structure and properties in high‐performance PA6/SEBS‐g‐MA/(PPO/PS) blends: The role of PPO and PS

This work aimed at studying the role of poly(phenylene oxide) (PPO) and polystyrene (PS) in toughening polyamide‐6 (PA6)/styrene‐ethylene‐butadiene‐styrene block copolymer grafted with maleic anhydride (SEBS‐g‐MA) blends. The effects of weight ratio and content of PPO/PS on the morphology and mechanical behaviors of PA6/SEBS‐g‐MA/(PPO/PS) blends were studied by scanning electron microscope and mechanical tests. Driving by the interfacial tension and the spreading coefficient, the “core–shell” particles formed by PPO/PS (core) and SEBS‐g‐MA (shell) played the key role in toughening the PA6 blends. As PS improved the distribution of the “core–shell” particles due to its low viscosity, and PPO guaranteed the entanglement density of the PPO/PS phase, the 3/1 weight ratio of PPO/PS supplied the blends optimal mechanical properties. Within certain range, the increased content of PPO/PS could supply more efficient toughening particles and bring better mechanical properties. Thus, by adjusting the weight ratio and content of PPO and PS, the PA6/SEBS‐g‐MA/(PPO/PS) blends with excellent impact strength, high tensile strength, and good heat deflection temperature were obtained. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45281.     

Effects of high nano‐SiO2 contents on properties of epoxy‐modified polybenzoxazine

High‐performance nanosilica composites based on epoxy‐modified polybenzoxazine matrices are developed. Chemorheological study of benzoxazine–epoxy resin mixtures reveals that processing window of the benzoxazine resin (BA‐a) is substantially broadened with an addition of the liquid epoxy. Glass transition temperature (T _g) of the BA‐a copolymerized with epoxy resin shows a synergistic behavior with a maximum T _g value (174°C) at the benzoxazine–epoxy mass ratio of 80:20. The copolymer at this composition is also used as a matrix for nano‐SiO₂ composites. A very low melt viscosity of the benzoxazine–epoxy mixtures promotes good processability with the maximum attainable nano‐SiO₂ loading up to 35 wt%. From scanning electron microscopy investigation, fracture surface of the 35 wt% nano‐SiO₂‐filled benzoxazine–epoxy composite reveals relatively homogeneous distribution of the nano‐SiO₂ in the copolymer with good particle wet‐out. In addition, very high reinforcing effect was also observed in such high content of the nano‐SiO₂, i.e., about 2.5 times in modulus improvement. This improvement is attributed to the strong bonding between the copolymer matrix and the nano‐SiO₂ through ether linkage as confirmed by Fourier‐transform infrared investigation. POLYM. COMPOS., 38:2261–2271, 2017. © 2015 Society of Plastics Engineers     

Tough polyamide 6/core–shell blends prepared via in situ anionic polymerization of ε‐caprolactam by reactive extrusion

In this study, the molten ε‐caprolactam (CL) solution of maleated styrene‐ethylene/butylene‐styrene block copolymer (SEBS‐g‐MA) and polystyrene (PS) containing catalyst and activator were introduced into a twin screw extruder, and polyamide 6 (PA6)/SEBS/PS blends were successfully prepared via anionic polymerization of CL by reactive extrusion. The mechanical properties measurements indicated that both the elongation at break and notched Izod impact strength of PA6/SEBS/PS (85/10/5) blends were improved distinctly with slight loss of tensile and flexural strength as compared to that of pure PA6. The images of transmission electron microscopy showed that a core–shell structure with PS core and poly (ethene‐co‐1‐butene) (PEB) shell was formed within the PA6 matrix. Fourier transform infrared was used to investigate the formation mechanisms of the core–shell structure. POLYM. ENG. SCI., 53:2705–2710, 2013. © 2013 Society of Plastics Engineers     

Application of styrene‐acrylonitrile random copolymer–polyarylate block copolymer as reactive compatibilizer for polyamide and acrylonitrile‐butadiene‐styrene blends

Styrene‐acrylonitrile random copolymer (SAN) and polyarylate (PAr) block copolymer were applied as a reactive compatibilizer for polyamide‐6 (PA‐6)/acrylonitrile‐butadiene‐styrene (ABS) copolymer blends. The SAN–PAr block copolymer was found to be effective for compatibilization of PA‐6/ABS blends. With the addition of 3.0–5.0 wt % SAN–PAr block copolymer, the ABS‐rich phase could be reduced to a smaller size than 1.0 μm in the 70/30 and 50/50 PA‐6/ABS blends, although it was several microns in the uncompatibilized blends. As a result, for the blends compatibilized with 3–5 wt % block copolymer the impact energy absorption reached the super toughness region in the 70/30 and 50/50 PA‐6/ABS compositions. The compatibilization mechanism of PA‐6/ABS by the SAN–PAr block copolymer was investigated by tetrahydrofuran extraction of the SAN–PAr block copolymer/PA‐6 blends and the model reactions between the block copolymer and low molecular weight compounds. The results of these experiments indicated that the SAN–PAr block copolymer reacted with the PA‐6 during the melt mixing process via an in situ transreaction between the ester units in the PAr chain and the terminal amine in the PA‐6. As a result, SAN–PAr/PA‐6 block copolymers were generated during the melt mixing process. The SAN–PAr block copolymer was supposed to compatibilize the PA‐6 and ABS blend by anchoring the PAr/PA‐6 and SAN chains to the PA‐6 and ABS phases, respectively. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2300–2313, 2002     

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     

Polymer blends of PA6 and PPE compatibilized by poly[methylene (phenylene isocyanate)] (PMPI) coupler

An oligomeric isocyanate, poly[methylene(phenylene isocyanate)] (PMPI), is demonstrated to be an efficient reactive compatibilizer for blends of polyamide-6 (PA6) and poly(2,6dimethyl-1, 4-phenylene ether)(PPE). Use of this compatibilizer results in substantial improvements in mechanical properties. The multiple functional isocyanate acts as a coupling agent and reacts with PA6 and PPE endgroups during melt processing to produce a PA6-co-PMPI-co-PPE mixed copolymer at the interface. This in situ-formed copolymer tends to reside at the interface to reduce the melt interfacial tension and enhance interface adhesion.     

Preparation and properties of core–shell nanosilica/poly(methyl methacrylate–butyl acrylate–2,2,2‐trifluoroethyl methacrylate) latex

A core–shell nanosilica (nano‐SiO₂)/fluorinated acrylic copolymer latex, where nano‐SiO₂ served as the core and a copolymer of butyl acrylate, methyl methacrylate, and 2,2,2‐trifluoroethyl methacrylate (TFEMA) served as the shell, was synthesized in this study by seed emulsion polymerization. The compatibility between the core and shell was enhanced by the introduction of vinyl trimethoxysilane on the surface of nano‐SiO₂. The morphology and particle size of the nano‐SiO₂/poly(methyl methacrylate–butyl acrylate–2,2,2‐trifluoroethyl methacrylate) [P(MMA–BA–TFEMA)] core–shell latex were characterized by transmission electron microscopy. The properties and surface energy of films formed by the nano‐SiO₂/P(MMA–BA–TFEMA) latex were analyzed by Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy/energy‐dispersive X‐ray spectroscopy, and static contact angle measurement. The analyzed results indicate that the nano‐SiO₂/P(MMA–BA–TFEMA) latex presented uniform spherical core–shell particles about 45 nm in diameter. Favorable characteristics in the latex film and the lowest surface energy were obtained with 30 wt % TFEMA; this was due to the optimal migration of fluorine to the surface during film formation. The mechanical properties of the films were significantly improved by 1.0–1.5 wt % modified nano‐SiO₂. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Reactive blends of polyamide 6 with polyester elastomer using coupling agents

In situ compatibilized melt blends of polyamide 6 (PA‐6) with polyester elastomer (PEL) were prepared in a corotating twin‐screw extruder using two types of coupling agent (CA): diglycidyl ether of bisphenol A (DGEBA) and 1,4‐phenylene bis(2‐oxazoline) (PBO). The notched impact strength of PA‐6 and PA‐6/PEL blends increased with the addition of coupling agent, especially DGEBA, and the maximum impact toughening of the blend was obtained with 0.6 mol % DGEBA, the composition of minimum domain size observed from SEM. Viscosities of the untreated blends increased over those of the base resins at low frequencies. Viscosities of both the base resins and the blends increased with the addition of CA, and the effect was much more pronounced with DGEBA, especially for PA‐6 and PA‐6–rich blends. The crystallization temperature (T_c) of PEL increased over 10°C, whereas the T_c of PA‐6 decreased by 2–3°C in the blends. With the addition of coupling agents, the crystallization melting temperature (T_m) and T_c of PA‐6 decreased by up to 5°C with DGEBA, implying that the crystallization of PA‐6 is disturbed by the in situ formed PA‐6–CA–PEL or PA‐6–CA–PA‐6 type copolymer. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3966–3973, 2004     

Boric acid incorporated on the surface of reactive nanosilica providing a nano‐crosslinker with potential in guar gum fracturing fluid

Small molecule borate crosslinker widely used in hydraulic fracturing treatment has a low crosslinking efficiency of less than 1%. Thus boric acid was introduced onto the surface of reactive nanosilica (denoted as nano‐SiO₂; size: about 20 nm) containing ? NH₂ group to obtain a nanosilica‐based crosslinker (denoted as nano‐crosslinker) with increased crosslinking efficiency, thereby broadening the application of nano‐SiO₂ in guar gum fracturing fluid. Moreover, the influence of the as‐prepared nano‐crosslinker on the rheological behavior of guar gum gel was investigated with borate crosslinker as a reference. Results show that boric acid chemically reacts with the amino group of the reactive nano‐SiO₂ to form N? B bond, which is beneficial to the formation of the network structure of guar gum gel. The guar gum gel crosslinked with the 57 ppm of borate based on the carrier of nano‐SiO₂ exhibits better temperature tolerance and shear resistance as well as breaking behavior than the counterpart crosslinked with 200 ppm of borate. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45037.     

Polyamide 6/ethylene‐butylene elastomer blends generated via anionic polymerization of ε‐caprolactam: Phase morphology and dynamic mechanical behavior

This paper reports about the polymerization of ε‐caprolactam monomer in the presence of low molecular weight hydroxyl or isocyanate end‐capped ethylene‐butylene elastomer (EB) elastomers as a new concept for the development of a submicron phase morphology in polyamide 6 (PA6)/EB blends. The phase morphology, viscoelastic behavior, and impact strength of the polymerization‐designed blends are compared to those of similar blends prepared via melt‐extrusion of PA6 homopolymer and EB elastomer. Polyamide 6 and EB elastomer were compatibilized using a premade triblock copolymer PA6‐b‐EB‐b‐PA6 or a pure EB‐b‐PA6 diblock reactively generated during melt‐blending (extrusion‐prepared blends) or built‐up via anionic polymerization of ε‐caprolactam on initiating ? NCO groups attached to EB chain ends (polymerization‐prepared blends). Two compatibilization approaches were considered for the polymerization‐prepared blends: (i) the addition of a premade PA6‐b‐EB‐b‐PA6 triblock copolymer to the ε‐caprolactam monomer containing nonreactive EB? OH elastomer and (ii) generation in situ of a PA6‐b‐EB diblock using EB? NCO precursor on which polyamide 6 blocks are built‐up via anionic polymerization of ε‐caprolactam. The noncompatibilized blends exhibit a coarse phase morphology, either in the extruded or the polymerization prepared blends. Addition of premade triblock copolymer (PA6‐b‐EB‐b‐PA6) to a EB? OH /ε‐caprolactam dispersion led to a fine EB phase (0.14 μm) in the PA6 matrix after ε‐caprolactam polymerization. The average particle size of the in situ reactively compatibilized polymerization‐prepared blend is about 1 μm. The notched Izod impact strength of the blend compatibilized with premade triblock copolymer was much higher than that of the neat PA6, the noncompatibilized, and the in situ reactively compatibilized polymerization blends. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2538–2544, 2004     

High performance polyamide 6 composites prepared by reactive extrusion

To improve the properties of polyamide 6 (PA6) composites, a series of modified PA6 composites was prepared by reaction extrusion. An amorphous PA6 was first obtained by the complexing reaction of Li⁺ in lithium chloride with amino groups, and then epoxy resins, nano‐SiO₂ as well as POE‐g‐MAH were in turn added into the PA6/LiCl system. The effect of different additives on the crystallization behavior and mechanical properties of PA6 composites was well‐studied by X‐ray diffraction (XRD), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), scanning electron microscopy (SEM), and mechanical properties tests. The results demonstrated that PA6 was amorphous at 6 phr lithium chloride and a network structure was formed in PA6 matrix in the presence of epoxy resins, thus the mechanical properties of composites greatly were enhanced. However too many nano‐SiO₂ particles might impair the tensile strength of PA6 composites. Additionally, a PA6 composite with excellent properties was obtained in the presence of POE‐g‐MAH due to the crystal form change in PA6 matrix and the strong interaction between PA6 and POE‐g‐MAH. POLYM. COMPOS., 35:985–992, 2014. © 2013 Society of Plastics Engineers