Edcleide Maria Araújo

Preparação de argilas organofílicas e desenvolvimento de nanocompósitos com matrizes poliméricas de polietileno e nylon6. Parte 1: comportamento mecânico

Bentonite clays from Boa Vista/PB were used to obtain organophilic clays. Organophilic clays were obtained with four types of quaternary salts of ammonium: asalkyldimethylbenzylammonium chloride (Dodigen), esthearildimethylammonium chloride (Praepagen), cethyltrimethylammonium chloride (Genamin) and cethyltrimethylammonium bromide (Bromide). The treated clays with salts and untreated clays were characterized by X- ray diffraction (XRD) and Fourier transformed infrared spectroscopy (FTIR). Then, the clays were incorporated into polyethylene (PE) and Nylon6 (PA6) polymer matrices using conventional processing techniques. The mixtures were characterized by XRD, scanning electron microscopy (SEM) and mechanical properties. The results obtained by FTIR showed the presence of specific groups of the salts in the clay, while their intercalation among the clay layers was verified by XRD. As for the mechanical properties, the mixtures were more rigid than the pure polymers.

Nanocompósitos de polietileno/argila bentonita nacional: influência da argila e do agente compatibilizante PE-g-MA nas propriedades mecânicas e de inflamabilidade

High density polyethylene/national bentonite clay nanocomposites were prepared with the melt intercalation technique. The effect of the clay without treatment and clay treated with quaternary ammonium salt Cetremide with polyethylene-graft-maleic anhydride as coupling agent was evaluated. The systems were characterized by flammability, mechanical and rheological properties, X ray diffraction and transmission electron microscopy. In general, the results of X ray diffraction and transmission electron microscopy showed partially exfoliated and/or intercalated structures with higher tensile modulus and torque value. The flammability test showed that the addition of clay in the polymer matrix and PE-g-MA reduced the burning rate, indicating an improved flammability resistance of the nanocomposites. In general, the system containing PE-g-MA coupling agent led to partially exfoliated nanocomposites with higher thermal stability than the high density polyethylene matrix. The polyethylene-graft-maleic anhydride promoted the exfoliation of clay and adhesion between matrix and filler, thus resulting in enhanced mechanical properties.

Desenvolvimento de nanocompósitos polipropileno/argila bentonita brasileira: I tratamento da argila e influência de compatibilizantes polares nas propriedades mecânicas

In this work, polypropylene/bentonite and polypropylene/compatibilizer/bentonite nanocomposites were prepared by the melt intercalation method, using a counter-rotating intermeshing twin-screw extruder attached to a Haake System 90 Rheometer. Initially the natural bentonite clay, from Boa Vista - PB, was subjected to a purification process and then treated with sodium carbonate. Further, it was treated with ammonium quaternary salt to obtain an organoclay. The clays were characterized, according to granulometric, by laser diffraction, chemical analysis, infrared spectroscopy - FTIR, and X ray diffraction - XRD. The granulometric and chemical analysis results showed that the purification process was effective for removing the coarse fractions and eliminating some accessory minerals. FTIR and XRD results showed that the ammonium quaternary salt was incorporated to the clay, confirming the organophilization. In the subsequent stage of this work, the bentonite organoclay was incorporated to both polypropylene (PP) and PP/compatibilizer (PPgAA and PPgMA are polypropylenes grafting acrylic acid and maleic anhydride, respectively). The formation of nanocomposites as well as the properties of PP/ORG (ORG - organoclay) and PP/compatibilizer/ORG mixtures were analyzed by XRD, MET and mechanical properties. XRD and MET results showed that the formation of interlayer/flocculated nanocomposites has occurred for PP/compatibilizer/ORG systems. The mechanical properties results showed that some mechanical properties (final elongation and toughness) have been considerably improved.

Fiberglass wastes/polyester resin composites: mechanical properties and water sorption

The mechanical properties of polyester/fiberglass composites were studied. The aim of this work was to evaluate the possibility of reusing the wastes taken from spray-up processing of Paraiba state Industries as reinforcement in polyester matrix composites. Composites with 20, 30, 40, 50 and 60 wt. (%) of recycled fiberglass were prepared by compression molding and compared with polyester/ virgin glass fiber composites. The mechanical properties and water sorption behavior were evaluated. The results showed that fiberglass wastes are promising to be reused in polyester resin composites. The impact strength was excellent. It can be concluded that the reusing of the fiberglass wastes is viable.

Morfologia de nanocompósitos de polietileno e poliamida-6 contendo argila nacional

High density polyethylene and nylon 6 nanocomposites with national bentonite clay were prepared with the melt intercalation technique. Different quaternary ammonium salts were used to obtain the organoclays. The unmodified and modified clays with the salts were incorporated in the polymer matrices and different procedures were used for the modification of clays: for the polyethylene nanocomposites, the clay was prepared with four quaternary ammonium salts and for the nylon 6 nanocomposites only one type of quaternary ammonium salt was used, which had its contents varied in the organophilization of the clay. The objective of this work was to obtain polyethylene and nylon 6 nanocomposites. They were characterized by transmission electron microscopy (TEM) and by X-ray diffraction (XRD). The results indicated that the polyethylene/organoclay systems presented structures of intercalated nanocomposites and/or partially exfoliated. The nylon 6/organoclay systems presented an exfoliated morphology with clay particles dispersed in the matrix.

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.

Preparação de argilas organofílicas e desenvolvimento de nanocompósitos de polietileno. Parte 2: comportamento de inflamabilidade

High density polyethylene/Bentonite clay nanocomposites were prepared by the melt intercalation technique. The clay was organically modified with different quaternary ammonium salts to obtain the organoclay. The unmodified and modified clays with the quaternary ammonium salts were introduced in a polyethylene matrix with 1 and 3 wt. % of clay. The thermal stability and the flammability of the systems were investigated by thermogravimetry and UL-94HB standard, respectively. The dispersion analysis and the interlayer distance (d001) of the clay particles were obtained by X ray Diffraction (XRD) and transmission electron microscopy (TEM). The organoclay presence in the polymer matrix increased the degradation temperature in relation to the pure polymer. The systems showed a reduction on the burning rate, indicating that the flammability resistance of the nanocomposites was improved.

Compatibilização de blendas de poliamida 6/ABS usando os copolímeros acrílicos reativos MMA-GMA e MMA-MA. Parte 1: Comportamento reológico e propriedades mecânicas das blendas

Polyamide 6 (PA6) is a semicrystalline polymer suitable to be used in engineering applications with a number of advantages, but its processing instability and relatively low impact strength are limiting aspects. The addition of acrylonitrile-butadiene-styrene (ABS) as an impact modifier to PA6 can improve these properties. However, this blend is immiscible and incompatible, hence the use of an adhesion promoter is necessary to improve the interfacial interaction between the phases. This study focuses on the influence of poly(methyl methacrylate-co-glycidyl methacrylate) (MMA-GMA) and poly(methyl methacrylate-co-maleic anhydride) (MMA-MA) copolymers as compatibilizers for PA6/ABS blends. These copolymers are miscible with SAN phase of ABS due to the presence of PMMA and they have also the esther and anhydride functional groups capable of reacting with polyamide end groups. PA6/ABS/MMA-MA blends showed an excellent impact performance, being super-tough at room temperature and maintaining a good ductility in subambient temperatures.

Tenacificação do poli(ácido lático) pela adição do terpolímero (etileno/acrilato de metila/metacrilato de glicidila)

The Poly(lactic acid) is a biodegradable polymer from renewable sources with potential to replace non-biodegradable polymers derived from petroleum. However its use is restricted in certain applications due to its high brittleness and rigidity. In order to make the PLA more tenacious, the terpolymer (ethylene/methyl acrylate/glycidyl methacrylate) - EMA-GMA was added to PLA in different concentrations. The addition of EMA-GMA to PLA turned the blends more stable during processing. The FTIR data confirmed the chemical reaction between groups in PLA and the EMA-GMA. A three fold increase was observed in the impact strength compared to pure PLA.