SbstractPolymer/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.
todos têm sido desenvolvidos para preparação de nanocompósitos polímero/argila [2] . Atualmente, vem sendo dada muita atenção aos nanocompósitos poliméricos, especialmente aos nanocompósitos desenvolvidos com silicatos em camada, devido à grande necessidade de materiais modernos de engenharia e ao fato dos polímeros puros não apresentarem as propriedades necessárias para certas aplicações [3] . IntroduçãoA partir da década de 60, começou-se a se reportar o desenvolvimento dos primeiros nanocompósitos de polímero/argila quando Blumstein citado por Leite [1] demonstrou, por meio da técnica de polimerização de monô-meros vinílicos, a intercalação de moléculas poliméricas entre as lamelas da montmorilonita. A partir daí, outros mé- Resumo: Nanocompósitos de poliamida 6/argila organofílica foram preparados pelo método de intercalação por fusão. A argila foi tratada com o sal quaternário de amônio (Genamin) visando-se a obtenção da argila organofílica (OMMT). Ela foi caracterizada por fluorescência de raio X (FRX) e difração de raio X (DRX) e, os resultados dessas análises mostraram a incorporação do sal entre as camadas da argila, tornando-a organofílica. Os nanocompósitos foram obtidos em extrusora de rosca dupla contra-rotacional, com 3% em peso de argila e, foram caracterizados por difração de raio X (DRX), microscopia eletrônica de transmissão (MET), caracterização mecânica sob tração, análise térmica dinâmico-mecânica (DMTA) e temperatura de deflexão térmica (HDT). Os resultados de DRX e MET mostraram estrutura esfoliada e/ou parcialmente esfoliada. As propriedades mecânicas sob tração dos nanocompósitos foram superiores às da poliamida 6 e, a análise por DMTA e HDT mostrou que a incorporação da argila organofílica na matriz polimérica, aumentou a rigidez (módulo de armazenamento) e a HDT do sistema, confirmando o efeito reforçante da argila no polímero.Palavras-chave: Nanocompósitos, poliamida 6, argila organofílica. Polyamide 6/Organoclay Nanocomposites: Effect of Matrix Molecular Weight on Structure and Mechanical and ThermalMechanical PropertiesAbstract: 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 reinforc...
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.
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.
Polyamide 66 (PA66)/Brazilian clay nanocomposites were produced via direct melt intercalation. A montmorillonite sample from the Brazilian state of Paraíba was organically modified with esthearildimethylammonium chloride (Praepagen), quaternary ammonium salt and has been tested to be used in polymer nanocomposites. The dispersion analysis and the interlayer spacing of the clay particles in matrix were investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Thermal behavior of the obtained systems was investigated by differential scanning calorimetry (DSC), thermogravimetry (TG), and heat deflection temperature (HDT) was reported too. The nanocomposites exhibited a partially exfoliated structure, very interesting HDT values which are higher than those of pure PA66, and good thermal stability.
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