Amanda Melissa Damião Leite

Structure and mechanical properties of polyamide 6/Brazilian clay nanocomposites

Recent interest in polymer/organoclays nanocomposites systems is motivated by the possibility of achieving enhanced properties and added functionality at lower clay loading as compared to conventional micron size fillers. By adding montmorillonite clay to polyamide 6 increases the Young modulus, yield strength and also improves barrier properties. In this work, nanocomposites of polyamide 6 with montmorillonite clay were obtained. The clay was chemically modified with three different quaternary ammonium salts such as: Dodigen, Genamin and Cetremide. In this case, a dispersion of Na-MMT was stirred and a salt equivalent to 1:1 of cation exchange capacity (CEC) of Na-MMT was added to the dispersion. The montmorillonite clay (untreated and treated by ammonium salts) and nanocomposites were characterized by X ray diffractions. Also the nanocomposites were characterized by transmission electron microscopy and mechanical properties. The results indicated that all the quaternary ammonium salts were intercalated between the layers of clay, leading to an expansion of the interlayer spacing. The obtained nanocomposites showed better mechanical properties when compared to polyamide 6. The clay acted as reinforcing filler, increasing the rigidity of nanocomposites and decreasing its ductility.

Nanocompósitos de poliamida 6/Argila organofílica: efeito do peso molecular da matriz na estrutura e propriedades mecânicas e termomecânicas

Polyamide 6/organoclay nanocomposites were prepared by the melt intercalation technique. The clay was treated with a quaternary ammonium salt (Genamin) to obtain the organoclay (OMMT), being characterized by X ray fluorescence (XRF) and X ray diffraction (XRD). The results confirmed the incorporation of the salt into the clay structure, i.e. the organophilization. The nanocomposites were obtained with a counter-rotational twin screw extruder with 3 wt.% of clay and characterized by XRD, transmission electron microscopy (TEM), tensile testing, dynamical-mechanical thermal analysis (DMTA) and heat deflection temperature (HDT). The XRD and TEM results showed exfoliated and/or partially exfoliated structures. The tensile properties were superior to those of the pure polyamide 6.The analysis with DMTA and HDT also showed that the incorporation of the organoclay into the polymer matrix increased the rigidity (storage modulus) of the system, confirming the reinforcing effect of the clay on the polymer.

Polyamide 6 Nanocomposites with Inorganic Particles Modified with Three Quaternary Ammonium Salts

The purpose of this study was to obtain polyamide 6 nanocomposites with national organically modified clay with three quaternary ammonium salts. The obtained results confirm the intercalation of molecules of salt in the clay layers, and a good interaction with the polymer, showing the formation of intercalated and/or partially exfoliated structures. The nanocomposites showed similar thermal stability compared to pure polymer, and the mechanical properties presented interesting and promising results.

Obtenção de membranas microporosas a partir de manocompósitos de poliamida 6/argila nacional. Parte 1: influência da presença da argila na morfologia das membranas

Polymeric membranes were produced from nylon 6 nanocomposites and a clay using the immersion-precipitation technique. The clay was organically modified by using a quaternary ammonium salt, Dodigen. Nanocomposites were obtained from nylon 6 with untreated clay (MMT) and treated clay (OMMT). The nanocomposites were studied by XRD and TEM. The morphological structure consisted of an exfoliated and partially exfoliated clay layers in the polymeric matrix. The membranes were produced by phase inversion method and characterized by XRD and SEM. The X-ray diffraction of the membranes confirmed the results for the nanocomposites. The SEM image of the membrane top surface showed irregular pores. As for the membranes with the nanocomposites, a larger number of better distributed pores were observed, indicating that the presence of the clay altered the membrane morphology. The cross section SEM image showed an asymmetric morphology structure, comprising two layers, namely a skin with small and closed pores, and a porous layer with large, uniformly distributed pores.

Spectroscopic and Diffractional Characteristics of Membranes and Polyamide 6/Regional Bentonite Clay Nanocomposites

Polymeric membranes are attracting attention of researchers and industries due to their lower costs. However, they also have lower mechanical resistance and chemical solvents, when compared with other materials. An improvement of polymer properties can be obtained by adding an inorganic nanoload in the structure. This study produced polyamide 6 / bentonite clay nanocomposites with a nominal content of 3%, and this was used in the processed form and in the organically modified form by cation exchange. The nanocomposites were produced by melt intercalation, and then, the membranes were obtained by the technique of immersion-precipitation. Bentonite, organophilic clay, the material processed in the extruder and the membranes were submitted to the x-ray diffraction (XRD) and infrared spectroscopy (ATR-FTIR). By both techniques, it was possible to prove the organic modification of clay and the change in the crystallinity of the nanocomposites and of the membranes.

Mechanical and thermomechanical properties of polyamide 6/Brazilian organoclay nanocomposites

Polymer/clay nanocomposites are a new class of composites with polymer matrices where the disperse phase is a silicate with elementary particles that have at least one of dimensions in nanometer order. Polyamide 6/Brazilian organoclay nanocomposites were prepared by melt intercalation, and the mechanical, thermal and thermomechanical properties were studied. The structure and morphology of the nanocomposites were evaluated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). It was verified by XRD and TEM analysis that all systems presented exfoliated structure predominantly. By thermogravimetry (TG), nanocomposites showed higher stabilities in relation to pure polymer. It was observed that the nanocomposites showed better mechanical properties compared to the properties of polyamide 6. The heat deflection temperature (HDT) values of the nanocomposites showed a significant increase in relation to pure polymer.

Evaluation of the effect of clay in polyethersulfone membranes

Polymeric membranes were produced from nanocomposites of polyethersulfone and clay, in proportions of 3 and 5% by weight of clay, by phase inversion technique using N, N-dimethylformamide as solvent. From X-ray diffraction analysis, an exfoliated and/or partially exfoliated structure was observed. From scanning electron microscopy images, it was observed that the nanocomposites membranes showed a surface free of defects, however, it was found in a cross section, an anisotropic structure, where the skin is thick and the porous support presents macropores. From water permeation flux measurements, it was found that the presence of the clay increased the flow, especially to the membrane with 5% of montmorillonite.

Influence of Processing Type in the Morphology of Membranes Obtained from PA6/MMT Nanocomposites

The nanocomposites have an extensive use in the current process of membrane preparation, taking into account their unique features as membranes. Thus, the study of nanocomposite processing to obtain membranes is highly important. In this work, Brazilian clay was used (Brasgel PA) for the preparation of polyamide/clay nanocomposite. The nanocomposites were produced in a high rotation homogenizer and in a twin screw extruder. From the nanocomposites and pure polymers processed in the two equipments, membranes were prepared by the immersion-precipitation method, using formic acid as solvent. By X-ray diffraction (XRD), the formation of exfoliated and/or partially exfoliated structures with changes in the crystalline phases of the polyamide was observed. From scanning electron microscopy images, it was observed that the processing clearly influenced the membrane morphology.

Evaluation of impact strength of polyamide 6/bentonite clay nanocomposites

Nanocomposites of polymer/clay have had much attention in recent years, particularly those developed with layered silicates due to the need of engineering materials more efficient than pure polymers for certain applications. The level of exfoliation of layered silicates in crystalline structure of polymer matrices has been studied and has been observed that it affects the crystalline behavior and the physical and mechanical properties. In this study, nanocomposites of polyamide 6 were obtained by the melt intercalation method, using a Brazilian bentonite modified with a quaternary ammonium salt. X-Ray Diffraction (XRD) results showed the incorporation of salt among the layers of clay, making it organophilic and that the nanocomposites presented exfoliated and/or partially exfoliated structures and confirmed by transmission electron microscopy (TEM). By thermogravimetry (TG), the results indicated that the presence of clay increased the thermal stability of polyamide 6. The impact properties of the nanocomposites showed inferior values in relation to the pure polyamide, in other words, decrease the toughness.

Influence of the Addition of Polypropylene and Compatibilizer in PA6 Membranes Obtained by Phase Inversion

Polymer blend is the name for the physical mixture of two or more polymers and/or copolymers, and this allows the obtention of new materials with superior properties to those of the pure components. The blends have been used in obtaining membranes in order to improve the barrier properties so that it can separate two phases totally or partially, restricting the transport of one or more chemical species. In this work, polymer membranes were obtained from blends of PA6/PPgAA and PA6/PP/PPgAA by phase inversion method and were studied by scanning electron microscopy (SEM) and X-ray diffraction (XRD). It was observed through the diffractograms that there were no significant variations in the characteristic peaks of PA6, and through SEM, it was observed the formation of microporous asymmetric membranes, where they showed a surface with higher porosity to the binary and ternary blends and presented smallest pore diameter for binary blends.