Synthesis of nylon 6–clay hybrid by montmorillonite intercalated with ϵ-caprolactam

It was found that montmorillonite was intercalated with ?-caprolactam. X-ray diffraction revealed that the chain axes of the ?-caprolactam were parallel to the montmorillonite plates. The intercalated montmorillonite was swollen by molten ?-caprolactam at 200°C. ?-Caprolactam and 6-aminocaproic acid (accelerator) were polymerized with the intercalated montmorillonite at 260°C for 6 h, yielding a nylon 6-clay hybrid. X-ray diffraction and transmission electron micrography revealed that the silicate layers of the hybrid were uniformly dispersed in the nylon 6 matrix. Mechanical properties of the hybrid were improved. The strength and the modulus of the hybrid increased compared with the previously reported nylon 6 clay-hybrid (NCH) synthesized by montmorillonite intercalated with 12-aminolauric acid. The heat distortion temperature (HDT) of the hybrid was 164°C, which was 12°C higher than that of NCH. © 1993 John Wiley & Sons, Inc.     

Novel preferred orientation in injection-molded nylon 6-clay hybrid

Nylon 6-clay hybrid (NCH) is a molecular composite of Nylon 6 and uniformly dispersed silicate monolayers of montmorillonite. In this study the preferred orientation of montmorillonite and Nylon-6 crystallites in a thick (3 mm) injection-molded bar of NCH has been investigated using x-ray diffraction and electron micrography (TEM). It is clear that this bar has a triple layer structure consisting of surface, intermediate, and middle layers which have different preferred orientation. In the surface layer both the silicate monolayers and the chain axes of Nylon-6 crystallites are parallel to the bar surface though the latter are randomly oriented within the plane. In the intermediate layer the silicate monolayers remain parallel to the bar surface but the Nylon-6 crystallites rotate by 90° so that the chain axes would be perpendicular to the bar surface or the silicate monolayers. In the middle layer the silicate monolayers are randomly oriented around the flow axis of the NCH bar while remaining parallel to it, and the Nylon crystallites are randomly oriented around the flow axis while keeping their chain axes perpendicular to the silicate monolayers. It may be concluded that such preferred orientation of Nylon 6 crystallites is induced by the clay because the crystallites in the pure Nylon 6 bar have no preferred orientation. ©1995 John Wiley & Sons, Inc.     

The discovery of polymer‐clay hybrids

The first successful example of a polymer‐clay hybrid was nylon‐clay hybrid (NCH), which is a nano‐meter‐sized composite of nylon‐6 and 1‐nm‐thick exfoliated aluminosilicate layers of the clay mineral. NCH was found and developed at Toyota Central Research and Development Laboratories over 17 years ago. The NCH containing a few weight percentages of clay exhibits superior properties such as high modulus, high strength, and good gas‐barrier properties. The key for the discovery of NCH was the polymerization of a nylon monomer in the interlayer space of the clay. This highlight presents the development of NCH from its discovery to its commercialization. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 819–824, 2004     

尼龙6/蒙脱土纳米复合材料的制备、结构与力学性能的研究

未经处理及经１１ 氨基酸处理的蒙脱土由于己内酰胺的引入而发生膨胀．己内酰氨可以在蒙脱土的硅酸盐片层间聚合，形成尼龙６／蒙脱土纳米复合材料．经１１ 氨基酸处理的蒙脱土和尼龙６分子间有很强的化学相互作用．与未经处理的蒙脱土相比，其所构成的纳米复合材料具有很好的力学性能．     

Synthesis and characterization of organosoluble,thermoplastic elastomer/clay nanocomposites

We synthesized organosoluble, thermoplastic elastomer/clay nanocomposites by making a jelly like solution of ethylene vinyl acetate containing 28% vinyl acetate (EVA‐28) and blending it with organomodified montmorillonite. Sodium montmorillonite (Na⁺‐MMT) was made organophilic by the intercalation of dodecyl ammonium ions. X‐ray diffraction patterns of Na⁺‐MMT and its corresponding organomodified dodecyl ammonium ion intercalated montmorillonite (12Me‐MMT) showed an increase in the interlayer spacing from 11.94 to 15.78 Å. However, X‐ray diffraction patterns of the thermoplastic elastomer and its hybrids with organomodified clay contents up to 6 wt % exhibited the disappearance of basal reflection peaks within an angle range of 3–10°, supporting the formation of a delaminated configuration. A hybrid containing 8 wt % 12Me‐MMT revealed a small hump within an angle range of 5–6° because of the aggregation of silicate layers in the EVA‐28 matrix. A transmission electron microscopy image of the same hybrid showed 3–5‐nm 12Me‐MMT particles dispersed in the thermoplastic elastomer matrix; that is, it led to the formation of nanocomposites or molecular‐level composites with a delaminated configuration. The formation of nanocomposites was reflected through the unexpected improvement of thermal and mechanical properties; for example, the tensile strength of a nanocomposite containing only 4 wt % organophilic clay was doubled in comparison with that of pure EVA‐28, and the thermal stability of the same nanocomposite was higher by about 34 °C. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 2065–2072, 2002     

聚对苯二甲酸乙二酯/蒙脱土纳米复合材料的制备和性能

讨论了聚对苯二甲酸乙二醇酯（ＰＥＴ）／层状硅酸盐（蒙脱土）纳米复合材料的制备技术和新材料的结构与性能特征．天然蒙脱土矿物经有机离子修饰剂处理后,参与ＰＥＴ的缩聚反应．ＴＥＭ测定证实蒙脱土在ＰＥＴ中的层厚分布为３０～５０ｎｍ．蒙脱土不影响ＰＥＴ的分子量及其分布．利用ＤＳＣ、ＷＡＸＤ、ＳＡＬＳ和偏光显微镜测定了ＰＥＴ／蒙脱土的结晶速率和结晶形态,说明ＰＥＴ／蒙脱土有着很快的结晶速率,不能生成球晶结构,一般只能生成结构不完整的微晶体．ＰＥＴ／蒙脱土在工程塑料和工业纤维领域有潜在的应用前景     

Infrared spectroscopy studies of structure and orientation in clay-reinforced polyamide-6 nanocomposites

Infrared (IR) spectroscopy was used to study the surface (by means of external reflection) and the bulk (by means of transmission measurements on microtomed slices) of specimens obtained by injection moulding of a commercial polyamide-6 clay-based nanocomposite material (NCH = nylon clay hybrid) at different mould temperatures and with different part geometries. Comparisons were made with equivalent non-reinforced polymer (PA-6). For the PA-6, the mould temperature influences the crystalline structure, with the γ phase predominating at 50°C and the α phase at 80°C. However, in the NCH material the ( phase is favoured, even at 80°C. In all cases the crystallinity increases on going from the surface to the core. The polymer chains are oriented in the flow direction, and the orientation is higher for parts with more elongated shapes. It does not vary greatly across the part thickness, except for a thin surface layer, where it is significantly higher. Both at the surface and in the bulk, the crystalline phase orientation is higher for the NCH than for the PA-6.     

Synthesis and properties of polyimide–clay hybrid

A polyimide hybrid with montmorillonite clay mineral has been synthesized from a dimethylacetamide (DMAC) solution of poly(amic acid) and a DMAC dispersion of montmorillonite intercalated with an ammonium salt of dodecylamine. Montmorillonite consists of stacked silicate sheets about 2000 Å in length, 10 Å in thickness. In this hybrid, montmorillonite is dispersed homogeneously into the polyimide matrix and oriented parallel to the film surface. Thanks to this special structure, this hybrid showed excellent gas barrier properties. Only 2 wt % addition of montmorillonite brought permeability coefficients of various gases to values less than half of those of ordinary polyimide. Furthermore, this hybrid had low thermal expansion coefficient. © 1993 John Wiley & Sons, Inc.     

一种液晶共聚酯/粘土纳米复合材料的制备及其相转变温度

一些无机微粒被广泛用做聚合物的增强材料,其中特别引起人们注意的是一种粘土,即蒙脱土（ｍｏｎｔｍｏｒｉｌｌｏｎｉｔｅ）．蒙脱土具有层状结构,其特点一是微粒尺寸小,二是可以和多种单体发生插层聚合反应,给出聚合物／蒙脱土纳米复合材料［１～３］．纳米复合材料指的是其基质中分散相的尺寸至少有一维小于１００ｎｍ数量级的复合材料．由于其纳米尺度效应、大的比表面积以及强的界面相互作用,纳米复合材料的物理力学性能优于相同组分常规复合材料．因此,无论从基本理论研究角度还是从应用角度上看,对聚合物纳米复合材料的研究都…     

Preparation of fluorinated methacrylate/clay nanocomposite via in‐situ polymerization: Characterization,structure, and properties

Novel fluorinated coating containing well‐dispersed silicate nanolayers is successfully produced via in‐situ free radical polymerization of 2,2,2‐trifluoroethyl methacrylate in the presence of vinylbenzyl‐functionalized montmorillonite with different loading. The organic modification of sodium montmorillonite is achieved through an ion exchange reaction with triphenylvinylbenzylphosphonium chloride as surfactant prepared before use by reaction with vinylbenyl chloride and phosphine. The following in‐situ polymerization in the presence of organomodified clay leads to fluorinated nanocomposites with of partially exfoliated and intercalated morphologies, as determined via XRD and TEM analysis. The nanoscale dispersion of clay layers is also evidenced by thermal analysis; a moderate decrease of the glass transition temperature about 2–8 °C compared to their virgin PMATRIF and an improvement of their thermal stability as evidenced by TGA. The wettability of the nanocomposite films is also studied by contact angle measurements with water. The incorporation of organomodified clays not only increases the hydrophobicity of the fluorinated polymers but also improves the surface properties of obtained nanocomposites. Compared the virgin homopolymer, the mechanical properties of the nanocomposites are reduced by addition of organomodifed clay at temperature from 30 to 60 °C, whereas this trend is gradually decreased at higher temperature. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 411–418     

Gas barrier of polystyrene montmorillonite clay nanocomposites: Effect of mineral layer aggregation

Three polystyrene (PS)/clay hybrid systems have been prepared via in situ polymerization of styrene in the presence of unmodified sodium montmorillonite (Na‐MMT) clay, MMT modified with zwitterionic cationic surfactant octadecyldimethyl betaine (C18DMB) and MMT modified with polymerizable cationic surfactant vinylbenzyldimethyldodecylammonium chloride (VDAC). X‐ray diffraction and TEM were used to probe mineral layer organization and to expose the morphology of these systems. The PS/Na‐MMT composite was found to exhibit a conventional composite structure consisting of unintercalated micro and nanoclay particles homogeneously dispersed in the PS matrix. The PS/C18DMB‐MMT system exhibited an intercalated layered silicate nanocomposite structure consisting of intercalated tactoids dispersed in the PS matrix. Finally, the PS/VDAC‐MMT system exhibited features of both intercalated and exfoliated nanocomposites. Systematic statistical analysis of aggregate orientation, characteristic width, length, aspect ratio, and number of layers using multiple TEM micrographs enabled the development of representative morphological models for each of the nanocomposite structures. Oxygen barrier properties of all three PS/clay hybrid systems were measured as a function of mineral composition and analyzed in terms of traditional Nielsen and Cussler approaches. A modification of the Nielsen model has been proposed, which considers the effect of layer aggregation (layer stacking) on gas barrier. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1733–1753, 2007     

丁二烯/苯乙烯/4-乙烯基吡啶共聚物蒙脱土嵌入混杂材料的研究

用聚合物乳液与蒙脱土的水分散体共混共凝的方法制备混杂材料.在混合过程中乳胶粒与蒙脱土晶层相互穿插,用盐酸絮凝,带正电的共聚物能够嵌入带负电的蒙脱土层间.萃取实验发现在混杂材料中蒙脱土吸附了大量的共聚物,说明蒙脱土晶层与共聚物之间存在静电吸附作用.XRD实验发现在混杂材料中蒙脱土的晶层结构发生了膨胀,并且变得混乱,而在共混物中蒙脱土晶层结构几乎不变.用TEM观察在混杂材料中蒙脱土晶层均匀分散于共聚物基体中,蒙脱土的层间距大于6nm.共聚物嵌入蒙脱土的层间,受到蒙脱土晶层的限制作用,共聚物的T_g发生了变化.交联以后的混杂材料的性能比共聚物有了较大的提高,蒙脱土晶层在共聚物基体中起到很好的补强作用.     

Effect of silane‐grafted polypropylene on the morphology of polypropylene and nylon 6/clay composites

Polypropylene (PP)/nylon 6/clay composites were prepared by compounding of PP, which had previously been treated with two kinds of silane compounds, with a master batch composed of 90 wt % of nylon 6 and 10 wt % of octadecyl amine‐modified sodium montmorillonite (NM10). The morphology of the composites was investigated by means of SEM, TEM, XRD, and energy‐dispersive X‐ray analysis. All of the composites exhibited a phase‐separated morphology, irrespective of whether the PP was modified with the silane compounds or not. However, adhesive strength between the modified PP and NM10 was stronger than that between neat PP and NM10. Moreover, the PP grafted with 3‐(trimethoxysilyl)propyl methacrylate (PP2) reacted with the silanol groups of the clay to form PP‐clay hybrid during the compounding, which acted as a compatibilizer for the PP/nylon 6/clay composite. PP2NM composite (PP2/NM10 80/20 on weight basis) exhibited a peculiar morphology, in that the PP‐rich phase formed island domains within the nylon 6‐rich domains, which were in turn dispersed in the PP‐rich continuous matrix. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 607–615, 2007.     

Effects of solid acidity of clay minerals on the thermal decomposition of 12-aminolauric acid

In this study, the effects of four types of clay minerals on the thermal decomposition of 12-aminolauric acid (ALA) were investigated. The decomposition temperature of ALA in ALA–clay complexes was in the range of 200–500 °C. The derivative thermogravimetry results indicated that all clay minerals exhibited catalytic activity on the decomposition of ALA. Pure ALA decomposed at approximately 464 °C, a temperature higher than the decomposition temperature of ALA in the presence of clay minerals. The decomposition temperature of ALA in different ALA–clay complexes follows the order illite (452 °C) > kaolinite (419 °C) > rectorite (417 °C) > montmorillonite (400 °C). This order is negatively correlated with the amounts of solid acid sites in the clay minerals, indicating that ALA is catalyzed by the solid acid sites in these minerals.     

Study on solvent permeation resistance properties of nylon6/clay nanocomposite

Nylon6/clay nanocomposite is prepared by mixing organized montmorillonite with nylon6 in HAAKE mixer. Solvent permeation resistance of the nanocomposite is measured to estimate the resistance to solvent permeation. The nanocomposite shows resistance to solvent permeation superior to that of pure nylon6. In addition, the clay content was found to significantly influence the solvent permeation resistance of nylon6, and the maximum improvement in barrier properties of nylon6/clay composite was found as the clay content reached an “optimum” value. By using proper composites and processing conditions, the permeation rate of toluene and ethanol in nylon6/clay nanocomposite is about 3 and 4 times slower than that in pure nylon6 at 50 °C. Our investigation indicated that the crystalline property of nylon6 has a strong impact on the sorption and diffusion of small molecules in the polymer. The improvement in solvent barrier properties of nylon6/clay nanocomposite is attributable to incorporation of an impermeable phase such as the layered silicate, improvement in crystallinity and decrease of crystalline dimension, which are evidenced by XRD, AFM, DSC and polarized optical microscopy (POM) studies.     

Polymorphic behavior in syndiotactic polystyrene/clay nanocomposites

X‐ray diffraction methods were used in an investigation of the structural changes in syndiotactic polystyrene (sPS)/clay nanocomposites. sPS/clay was prepared by the intercalation of sPS polymer into layered montmorillonite. Both X‐ray diffraction data and transmission electron microscopy micrographs of sPS/clay nanocomposites indicated that most of the swellable silicate layers were exfoliated and randomly dispersed in the sPS matrix. The X‐ray diffraction data also showed the presence of polymorphism in the sPS/clay nanocomposites. This polymorphic behavior was strongly dependent on the thermal history of the sPS/clay nanocomposites from the melt and on the content of clay in the sPS/clay nanocomposites. Quenching from the melt induced crystallization into the α‐crystalline form, and the addition of montmorillonite probably increased heterophase nucleation of the α‐crystalline form. The effect of the melt crystallization of sPS and sPS/clay nanocomposites at different temperatures on the crystalline phases was also examined. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 736–746, 2002     

Poly(lactic acid) nanocomposites with various organoclays. I. Thermomechanical properties,morphology, and gas permeability

The thermomechanical properties, morphology, and gas permeability of hybrids prepared with three types of organoclays were compared in detail. Hexadecylamine–montmorillonite (C₁₆–MMT), dodecyltrimethyl ammonium bromide–montmorillonite (DTA‐MMT), and Cloisite 25A were used as organoclays in the preparation of nanocomposites. From morphological studies using transmission electron microscopy, most clay layers were found to be dispersed homogeneously in the matrix polymer, although some clusters or agglomerated particles were also detected. The initial degradation temperature (at a 2% weight loss) of the poly(lactic acid) (PLA) hybrid films with C₁₆–MMT and Cloisite 25A decreased linearly with an increasing amount of organoclay. For hybrid films, the tensile properties initially increased but then decreased with the introduction of more of the inorganic phase. The O₂ permeability values for all the hybrids for clay loadings up to 10 wt % were less than half the corresponding values for pure PLA, regardless of the organoclay. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 94–103, 2003     

Thermal stability studies on clay nanocomposites prepared from a degradable poly(ester amide) constituted by glycolic acid and 6-aminohexanoic acid

An intercalated nanocomposite of the organically modified montmorillonite Cloisite C25A and a degradable poly(ester amide) based on glycolic acid and 6-aminohexanoic acid units (poly(glc-alt-amh)) was prepared using a twin-screw co-rotating extruder. The non-isothermal degradation kinetics was investigated by thermogravimetric analysis (TG and DTG) in the temperature range of 50–600 °C at five heating rates (2, 5, 10, 20 and 40 °C/min) and compared with the neat polymer. Significant differences were found since the nanocomposite showed three degradation steps instead of the two decomposition processes detected in the pristine sample. The onset mass loss temperature decreased in the nanocomposite due to the presence of the organo-modifier compound, but the presence of the silicate layers significantly decreased the degradation rate at the last stages of decomposition. Kinetic analysis was performed using the Kissinger method and the isoconversional (Kissinger–Akahira–Sunose and Friedman) methods. The true kinetic triplets (E, A, f(α)) were determined for the first two steps of degradation through the Coats–Redfern and the Invariant Kinetic Parameters methods. The results clearly indicated that the presence of the organo-modified clay modified the mechanisms of degradation.     

Synthesis of Novolac/Layered Silicate Nanocomposites by Reaction Exfoliation Using Acid‐Modified Montmorillonite

Novolac/layered silicate nanocomposites were synthesized by condensation polymerization of phenol and formaldehyde catalyzed by H‐montmorillonite (H‐MMT). Exfoliation of the clay was investigated by X‐ray diffraction and transmission electron microscopy (TEM). It turned out that the intra‐gallery condensation of phenol and formaldehyde played a predominant role in the exfoliation of MMT. Exfoliated clay plates with interlayer spacings of 10–30 nm were dispersed in the matrix uniformly as shown by the TEM micrograph.     

Structural characteristics and moisture sorption behavior of nylon‐6/clay hybrid films

The structure of nylon‐6 hybrids with synthetic or natural clays was investigated for melt‐pressed films with Fourier transform infrared spectroscopy, wide‐angle X‐ray diffraction, and differential scanning calorimetry in comparison with the nylon‐6 homopolymer. In contrast to the development of familiar α‐form crystals in plain nylon‐6 film, the hybrid films produced γ‐form crystals when nylon‐6 was conjugated with synthetic mica, whereas the hybridization with natural montmorillonite gave rise to both α‐ and γ‐crystalline modifications. The degree of crystallinity of the nylon‐6 hybrid with synthetic mica was the highest of the three series. Moisture sorption isotherms obtained for these nylon‐6‐based films were all typically sigmoid‐shaped, although the prevalence of a higher crystallinity in the hybrid samples lowered the degree of moisture regain. The sorption behavior was analyzed well in terms of the parameters of a Brunauer–Emmett–Teller multiplayer adsorption model and a Flory–Huggins treatment. It was also observed that the cluster formation of the water adsorbed into the nylon‐6 matrix tended to be restricted by the hybridization with clay. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 40: 479–487, 2002; DOI 10.1002/polb.10106