Propriedades Mecânicas e Reológicas de Nanocompósitos de Poliamida 6 com Argila Organofílica Nacional

Abstract

Resumo: Nanocompósitos de poliamida 6 com argila organofílica foram preparados pelo método de intercalação no estado fundido. Foram estudadas as propriedades reológicas e mecânicas de nanocompósitos com argila nacional. A argila utilizada foi tratada com o sal quaternário de amônio (Cetremide) e foi caracterizada por Espectroscopia no Infravermelho (FTIR) e difração de raios X (DRX). Os resultados evidenciaram a incorporação do sal na argila e sua organofilização. Para a obtenção dos nanocompósitos, foram preparados concentrados de PA6/argila (1:1) em (m/m) e estes foram adicionados na poliamida 6, em quantidade de 3% de argila no composto final, utilizando uma extrusora de rosca dupla corrotacional. Posteriormente, as amostras foram moldadas por injeção e caracterizadas por: reometria capilar, DRX, MET e ensaios mecânicos (tração e impacto). Os resultados de reometria capilar mostraram que a presença da argila organofílica na PA6 aumentou a viscosidade dos sistemas. Por DRX e MET, foi verificado que todos os sistemas apresentaram predominância de estrutura esfoliada. As propriedades mecânicas sob tração foram melhores do que as da poliamida 6. Palavras-chave: Nanocompósitos, poliamida 6, argila organofílica. Mechanical and Rheological Properties of Nanocomposites of Polyamide 6 with National OrganoclayAbstract: Nanocomposites of polyamide 6 with organoclay were prepared by melt intercalation and their rheological and mechanical properties were studied. The clay was treated with the quaternary ammonium salt (Cetremide) and characterized by Infrared Spectroscopy (FTIR) and X-ray diffraction (XRD). The results showed the incorporation of salt in the clay and its organophilization. A master was prepared with PA6/clay (1:1) by weight and this was added to the pure polyamide 6 to reach the nominal proportion of 3% of clay, using a corrotacional twin screw extruder. The samples were molded by injection and characterized by: capillary rheometry, XRD, TEM and mechanical testing (tensile and impact). The results of capillary rheometry showed that the presence of organoclay in the PA6 increased the viscosity of the systems. With XRD and TEM, it was verified that all systems presented predominantly exfoliated structure. The tensile properties of the nanocomposites were better than those of pure polyamide 6.

Evaluation of impact strength of polyamide 6/bentonite clay nanocomposites

“…It is interesting to notice that the nanocomposites patterns presented the same behavior regardless the processing variables used. These results are consistent with other works reported in the literature 15,16 .…”

Mechanical and thermomechanical properties of polyamide 6/Brazilian organoclay nanocomposites

“…This increase is because of the stronger interfacial interaction between the matrix and the clay layers, especially when they are more dispersed 10. On the other hand, the elongation at break decreased, as expected, due to the particles of the clay acted as a barrier preventing the mobility of the polymer chains and reducing the elongation [15,24] . T m = Melting temperature taken at the melt peak; ∆H c = Crystallization Enthalpy; ΔH m = Heat of fusion, calculated from the melting peak; T onset = onset temperature.…”

“…The mixture was stirred for more 20 minutes. After 24 h the mixture of bentonite and the salt were washed with distilled water for several times to remove the salt excess and it was dried at 60°C for 48 h, and finally, passed in a sieve 200 mesh detailing of the procedure is described by Díaz [22,23] and others authors [8,11,15,24] . In the nanocomposite preparation, before any processing step, all the materials with PA6 were dried in an oven with circulating air at 80°C for 1 h. Afterwards, these materials were kept in an oven under vacuum at 80°C for 24 h. The nanocomposites were prepared by two steps.…”

“…After all the material has been extruded, granulated and dried at 80 °C in a vacuum oven for 24 hours, it was submitted to the process of injection molding in Allrounder injection Arburg 270/30 ton, with the following injection conditions: injection pressure of 38 MPa; temperature profile of 250 °C; mould temperature of 65 °C; mould cooling of 20s; holding pressure of 32 MPa and injection speed of 27 cm 3 /s. The preparation of nanocomposites was according to literature [8,11,15,24] . The thermogravimetry analysis (TG) was performed on a Thermal Analyzer TGA Q500 (TA Instruments), using about 5 mg of sample heating rate of 20 °C min -1 and a sample holder of alumina.…”

Characterization of Sodium Bentonites: Effect of Treatment with Ammonium Salt-Free Organic Surfactant

“…[8][9][10][11] As argilas organofílicas são usualmente caracterizadas por difração de raios X, pois esta técnica permite, a partir do difratograma, calcular a distância interplanar basal; por espectroscopia na região do infravermelho com transformada de Fourier, em que determinadas bandas de absorção indicam a presença do surfactante e a medida de área específica para avaliar transformações estruturais ocorridas nos processos de modificação. 12 O fato da argila organofílica ser hidrofóbica e apresentar elevada área superficial específica, a torna interessante para diversas aplicações tecnológicas, como por exemplo, matéria-prima para diversos produtos (tintas, vernizes, graxas, resinas e cosméticos) 13 ena preparação de nanocompósitos poliméricos, [14][15][16][17] atuando na forma de agente de reforço 18 e de barreira a gases. 19,20 Na prática, tanto os surfactantes de sais de amônio quanto de fosfônio apresentam limitações.…”