Keila Machado Medeiros

Study of Morphology Membrane of Polymeric Nanocomposites Obtained by Phases Inversion

In this work, were obtained nanocomposite membranes polyamide66/Paraíba bentonite clay, treated with a quaternary ammonium salt in order to make it organophilic. The membranes were prepared as thin films using the technique of phase inversion from the nanocomposites obtained by solution. The membranes were characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetry (TG) and scanning electron microscopy (SEM). By means of X-ray diffractogram, it was revealed that the membranes remained organically treated clay presented exfoliated and/or partially exfoliated structure. From curves of DSC and TG, it was observed that membrane of PA66 with 3% w/w of with treatment clay showed higher thermal stability compared with the same content of clay without treatment. From the SEM photomicrographs, there was a selective layer (skin filter) on top and one porous layer at the bottom of all membranes studied. Moreover, it was verified that the presence of clay provided a significant structural modification in the membranes of polymer nanocomposites.

Analysis of the Efficiency of Surface Treatment of Bentonite Clay for Application in Polymeric Membranes

The bentonite clay fillers are mostly used for the development of nanocomposites, due to having characteristics which provide to obtain in nanometric particles. The bentonite clay was treated with an ammonium quaternary salt to modify it to organophilic clay. The polymeric membranes and nanocomposites were prepared using the phase inversion technique. The bentonite and organophilic clays were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The membranes were characterized by XRD. The results of XRF, XRD and FTIR confirmed the presence of quaternary ammonium salt in the organoclay structure. The XRD diffraction patterns of nanocomposites membrane showed exfoliated and/or partially exfoliated structure. According to the obtained results, it could be seen that the treatment performed on the surface of the clay was quite promising and efficient to be added as nanofillers on polymeric membranes.

Obtaining of Polyamide 6.6 Plane Membrane Application in Oil-Water Separation

Nanocomposites are a class of materials formed by hybrids of organic and inorganic materials, where the inorganic phase is dispersed at the nanometer level in a polymeric matrix. Several polymers have been used as matrices for the preparation of polymer / clay nanocomposite, among which, polyamide 6.6, by presenting excellent chemical, thermal and mechanical. The nanocomposites exhibit excellent properties the point of view optical, electrical and barrier, and reduced flammability. In this research, micro-porous membranes were obtained from the polyamide 6.6/argila montmorillonite nanocomposite, in order to verify its application in the separation water / oil. The results obtained by scanning electron microscopy (SEM) showed that the obtained membranes have a dense layer and a porous layer, and that after the test oil-water separation was observed that the relative flow (J/J0) was greater in compositions with 3% clay, 1.5 bar pressure.

Development of Polymer Membranes Modified with a Porogenic Agent

Membrane is a barrier that separates two phases and limits wholly or partially carrying one or several chemical species present in the phases. In this study, membranes with a polyamide6 porogenic agent were obtained. The membranes were prepared as thin films by phase inversion method using the immersion technique, precipitation by varying the percentage of porogenic agent introduced and the time of exposure of the membranes during the process of immersion-precipitation. The membranes obtained were characterized by scanning electron microscopy (SEM). From the SEM photomicrographs, a large morphological change was observed over the entire surface layer of the membranes, significantly affecting the size and number of pores. Furthermore, porogenic agent promoted the formation of pores and the increase in planar microporous membranes obtained.

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.

Study of Nanocomposites of Polyamide 6.6/National Bentonite Clay

Polymers nanocomposites are a class of materials where inorganic substances with nanometrics dimensions are modified and used as dispersed loads in polymers matrices. In this work, polyamide 6.6 was chosen because of its excellent chemical, mechanical and thermal properties. The bentonite clay was treated with quaternary ammonium salt (Cetremide®) to make it organophilic and to improve the interaction with the polymer matrix. It was verified by the Torque Rheometry that the system with salt presented a bigger torque in relation to the torque of the system with untreated clay and pure polyamide 6.6. The nanocomposites presented an exfoliated and partially exfoliated structure, as evidenced by XRD. By DSC, it was observed that the treated clay increases the decomposition temperature of the nanocomposite.

Membranes from Nylon 6/Regional Bentonite Clay Nanocomposites

In this work, it was produced hybrids organic/inorganic membranes of nylon6 and clay mineral constituted of silicate layers, from the interior of the Paraiba. The sodic clay was used in the untreated and treated (with quaternary ammonium salts) form (to become compatible with polymer). Commercial salts Genamin and Cetremide were used to prepare organoclay by cationic exchange reaction in aqueous phase. The nanocomposites were obtained by melt intercalation and from these nanocomposites it was synthesized the membranes for dissolution in predetermined amounts of formic acid and a precipitation in a non-solvent, also called immersion-precipitation technique to prepare thin films. Thus, on the basis of the results, it can be observed that the presence of the treated and untreated clay confer a significant alteration in the structure/morphology of the pores and the porosity of the membrane.

Influence of Clay Content in Membrane Morphology of Polymer Polyamide 6.6/Montmorillonite Clay

Membranes can be defined as a barrier that separates two phases and is widely applied in industrial separation processes. The development of membrane separation processes (PSM) has the major advantage of phase change without separation of components, besides selectivity and simplicity of operation. The addition of mineral fillers in polymers is intended for the cost reduction and increase in rigidity of the materials. When these loads have sizes of nanometric dimensions, this system is called nanocomposites, which exhibit improved properties compared to the pure polymers or conventional composites. Microporous membranes were obtained from polyamide 6.6 nanocomposites of varying amounts of regional montmorillonite clay through the immersion-precipitation process. In general, the membranes showed a filter skin, which contains very small pores and a porous layer, with variations in microstructure, detected by scanning electron microscopy (SEM).

Polyamide66/National Bentonite Clay Nanocomposites Membranes for Water-Oil Separation

Membranes can be defined as polymer film that acts as a semipermeable barrier to filtration in a molecular scale, separating two phases. In this work, microporous membranes were obtained from hybrid organic/inorganic polyamide66 (PA66) and clay mineral from Paraíba State, treated with a quaternary ammonium salt in order to make it organophilic. The membranes in the form of thin films were prepared by immersion-precipitation technique from the nanocomposites obtained by solution, with a pre-determined reaction time of 2 h, with characteristics suitable to be used in microfiltration process for separation of the oil present in water. Samples of natural and organophilic clay were characterized by X-ray fluorescence (XRF) and Fourier transform infrared spectroscopy (FTIR). Meanwhile, the membranes were characterized by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). The results of FRX and FTIR confirmed the presence of quaternary ammonium salt in the clay structure after treatment with organic salt. Through DSC analysis it was observed almost no change in the melting temperature of the pure polyamide66 membranes. By SEM, it was revealed an asymmetric morphology consisting of a skin layer and a porous sublayer, showing the pore size distribution appropriated to water-oil separation.

Study of Hybrid Membranes Prepared with the Addition of Calcium Chloride

In this work, hybrid membranes were obtained with the addition of calcium chloride (CaCl2). Hybrids were obtained by the melt intercalation method. Membranes were prepared by phase inversion technique. Hybrid and hybrid membranes were characterized by differential scanning calorimetry (DSC). The DSC curve of the polymer and polymer membrane was changed by addition of the clay, increasing the degree of crystallinity. For all membranes, it was observed the existence of two endothermic peaks corresponding to the two crystalline phases of the polymer characteristics, in the range of 220 °C related to the alpha phase and, in the range of 210 °C related the gamma phase. In addition, there was the appearance of an endothermic peak at about 70 °C, related to the temperature of the dry polymer glass transition. The addition of CaCl2 changed the crystalline behavior of hybrids, becoming less evident the nucleating effect of the clay.