Tomás Jefférson Alves de Mélo

Preparation of Poly(Lactic Acid)/Bentonite Clay Bio-Nanocomposite

Recent advances in biodegradable polymers have attracted a great interest not only in traditional areas such as biomedical and pharmaceutical industry, but also in packaging applications, articles and injected membranes. The aim of this work was to produce bio-nanocomposites poly (lactic acid) - PLA with bentonite clay. The bio-nanocomposites were produced by melt intercalation with incorporation of 1 to 3 wt% of organoclay. The degree of dispersion of clays in the polymer, and consequently the structure of bio-nanocomposites produced was evaluated by X-ray diffraction (XRD), and the thermal properties were studied by differential scanning calorimetry (DSC). XRD results indicated the formation of intercalated structures. It was observed the appearance of crystalline melting double peaks in bio-nanocomposites PLA.

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.

Influence of Organoclay on the Physical Properties of Polyethylene Nanocomposites

In this work, polyethylene/montmorillonite clay nanocomposites were produced by melt intercalation. The clays were treated with quaternary ammonium salts and then treated and untreated clays were introduced in polyethylene. The clays were characterized by X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FT-IR). The nanocomposites were characterized by mechanical and flammability properties. The results showed that the mechanical properties were improved by introduction of organoclay in polyethylene matrix. By adding only 3wt% montmorillonite, the burning rate of the nanocomposites was reduced by 17% in relation to PE matrix.

Influence of Molecular Weight of Polyamide 6 in Obtaining of Nanocomposites with National Organoclay

Much attention is being given to developing nanocomposites with layered silicates, owing to the great need for advanced materials engineering and the fact that the pure polymers do not present the behavior or properties needed for certain applications within that context, the objective of this study was to influence of the molecular weight of polyamide 6 in obtaining nanocomposites with national organoclay. For this, the mixture of polyamide 6/ organoclay was processed in a twin screw extruder, and then was characterized by thermogravimetry (TG), X-ray diffraction (XRD) and heat deflection temperature (HDT). It was then possible to observe by XRD to obtain a structure exfoliated or partially exfoliated in the studied systems. For TG, it was found that the nanocomposites were stabilities higher than the pure polymer. And the values of HDT of systems were significantly higher than those of pure polyamide 6.

Evaluation of the Behavior of Brazilian Bentonite Clays with Different Quantity of Quaternary Ammonium Salt

Paraíba is the main natural bentonite producing state of Brazil. Besides the advantage of abundance of bentonite clays, its transformation in organoclay is a simple method and there is only little study about the commercialization of Brazilian organoclays. In this work, Brazilian bentonite clay was organophilized with different quantity of a quaternary ammonium salt, such as 100, 125 and 150 wt.% in relation to Cationic Exchange Capacity (CEC) of the clay. The clays were characterized by X-ray Fluorescence (XRF), X-ray Diffraction (XRD), Thermogravimetry (TG) and Nuclear Magnetic Resonance (NMR). It was observed that with increasing amount of salt the degree of dispersion of the clay increased, leading in some cases to the delamination of the clay layers and its loss of thermal stability.

Influence of Speed of Processing in the Mechanical and Thermomechanical Properties of Polyamide 6 / Organoclay Nanocomposite

The improvement in the properties of nanocomposites is achieved with a load volume fraction of up to 10% due to the very high ratio of the load aspect. Moreover, they have the advantage of being processed with conventional equipment and techniques (extrusion, injection, etc.) used for polymers. In order for the clay to be uniformly dispersed in the polymer and there to be good interaction with the polymer matrix, superficial treatments of the clays with organic salts are essential for it to become organophilic, and, thus the material obtained has better performance. In this study, it was evaluated the influence of two speeds (100 and 200 rpm) of processing and thermo mechanical properties of nanocomposites with 3% of bentonite clay prepared with two speeds and two threads. The nanocomposites showed better properties as compared to properties of polyamide 6, especially the samples heated at screw speed of 100 rpm.

Mechanical and Morphological Behavior of Blends Obtained from Biopolymers (PLA/PLC)

In this work, the effect of the PCL content and E-GMA compatibilizer on the mechanical properties and morphology of poly (lactic acid) - PLA/ poly (ε-caprolactone)-PCL blends was investigated. The results of the mechanical properties showed that there was a reduction in the elastic modulus and tensile strength when PCL was added to PLA. The decrease in the modulus was more pronounced when the PCL content was increased from 10 to 20% (wt). The PLA/PCL/E-GMA blend showed the lower modulus and tensile strength. This blend also presented the higher elongation at break and impact strength. The morphology analysis by SEM showed that the PLA/PCL blends where characterized by lack of adhesion between the PLA and PCL phases. The presence of E-GMA in the PLA/PCL/E-GMA blend improved the adhesion between the PLA and PCL phases.Keywords: poly (latic acid); poly (ε-caprolactone); polymer blends; compatibilizer

Obtaining of Polymer Films from Nylon 6/Bentonite Clay Nanocomposites: Structural Characterization

The nanocomposites are hybrid materials where at least one of the components has nanometric dimensions and in the same way as traditional composites are formed, one of the components is the matrix in which nanoparticles are dispersed. One of the possibilities of applications of nanocomposites is to obtain polymer films for applications in the barrier, or separation promoted by the dispersion of the clay lamellae. In this work, nanocomposites of nylon 6/bentonite clay were obtained by melt intercalation. The used clay was the Brasgel PA, and quaternary ammonium salt was Praepagen-HY, used in organophilization of the clay. By XRD, it was observed the disappearance of the characteristic peak of clay, and this can be facilitate the possible exfoliation of clay in the produced films from the nanocomposite. By SEM, it was observed, an apparently dense layer with no pores.

Rheological Study of Polyamide 6/Waste Styrene-Butadiene Rubber (SBR) Blends

The application of polyamides is limited by low impact performance when notched in room temperature conditions. This situation is worsening, especially for use in temperatures below zero degrees Celsius. One way to outline this limitation is to prepare polymer blends where the dispersed phase is an elastomer, and then classified as an immiscible blend. Therefore, this study aims to develop polyamide 6/waste styrene-butadiene rubber (SBR) blends, with addition of compatibilizer PP-g-MA and PE-g-MA in order to achieve a balance between stiffness and tenacity. The results obtained with the rheological study showed that mixtures of PA6/PE-g-MA presented the best results in comparison with mixtures of PA6/PP-g-MA, indicating that there was probably a reaction between the components, which may allow a better dispersion and thus can achieve better properties.

Systematic Characterization of Different Quaternary Ammonium Salts to be Used in Organoclays

Studies of degradation have verified that the decomposition of some quaternary ammonium salts can begin to be significant at the temperature of about 180 ° C and like most thermoplastics are processed at least around this temperature, the thermal stability of the salt in clay should always be considered. Some salts are more stable than others, being necessary to study the degradation mechanisms of each case. In this work, four quaternary ammonium salts were characterized by differential scanning calorimetry (DSC) and thermogravimetry (TG). The results of DSC and TG showed that the salts based chloride (Cl-) anion begin to degrade at similar temperatures, while the salt based bromide (Br-) anion degrades at higher temperature. Subsequently, a quaternary ammonium salt was chosen to be used in organoclays, depending on its chemical structure and its thermal behavior.