Filme à base de nanocompósito de polietileno de baixa densidade e argila organofílica

• Autor(a) principal: Santos, Johnson Clay Pereira
• Data de Publicação: 2013
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/481
• topic: nanotecnologia; Argila organofilica; Nanocompósito; Nanotechnology; Organoclay; Nanocomposite; CNPQ::CIENCIAS AGRARIAS::CIENCIA E TECNOLOGIA DE ALIMENTOS::TECNOLOGIA DE ALIMENTOS

Technological advances are associated with the improvement of the properties of existing materials and the development of new materials that provide superior structural and functional performances. Thus, many technologies used in a daily basis would not be feasible without the input of novel materials. A good example of such development is composites. The present work aimed to elaborate and characterize a low density polyethylene (LDPE)-based nanocomposite films incorporated with montmorillonite clay (MMT) in different concentrations and types (Cloisite 20 A and Cloisite 93 A). The films were processed by the melt intercalation technique in a twin screw extruder set to present four heating zones (175, 185, 190 and 190 °C). The nanocomposites were prepared in a mixing chamber with two different types of clay and concentrations (0, 0.5, 1.0, 1.5, 2.5, 3.5 and 4.5% w/w). The nanocomposites were mixed for 7 minutes at 190 °C and 80 rpm in the chamber capable of mixing 50 g per batch and then were pressed and cut for subsequent extrusion in a single screw extruder. The nanocomposite films were characterized by X-ray diffraction (XRD), absorption spectroscopy in the infrared Fourier transform spectroscopy (FTIR), scanning electron microscopy (SEM), atomic force microscopy (AFM), thermogravimetric analysis (TGA) and rheology. The tests led to the formation of nanocomposites with good dispersion and exfoliation, especially in concentrations of clay lower than 3.5%. XRD showed a marked increase in the basal spacing with increasing clay concentration, but at concentrations of 3.5 and 4.5% this distance decreased, indicating that there was a good dispersion of the clay for small concentrations. Micrographs showed rod morphology, suggesting exfoliation and intercalation in concentrations of 1.5 and 2.5%, whereas at a concentration of 4.5%, the surface morphology of the samples showed agglomeration, implying hampered dispersion. FTIR and AFM analyses corroborate the results of XRD and SEM, as also indicated better interaction of MMT with LDPE in low clay concentrations. TGA analysis showed a remarkable increase in the thermal decomposition temperature after clay was incorporated in the polymeric matrix. Rheological tests were unable to determine the best characteristic of the material as to the incorporation of clay into LDPE.