Luciana De Simone Cividanes

Sonocatalytic Degradation of Methylene Blue in the Presence of TiO2 Doped Carbon Nanostructures—Catalytic and Adsorption Comparison by Different Carbon Forms

The main objective of this work was to evaluate nanocomposites formed by TiO2-CNT (carbon nanotube) and TiO2-C (resorcinol/formaldehyde) via a sonocatalytic process. The synthesis of composites was performed by the sol-gel method using titanium isopropoxide (Ti(OPr)4-TTIP), acetic acid and ethylene glycol as dispersing medium. Ultrasound was used as the irradiation source and methylene blue was chosen as a model substance. In addition, the adsorption capacity was studied in an attempt to achieve greater ratio degradation/adsorption. The methylene blue concentration after adsorption and sonocatalysis was investigated by UV–vis spectroscopy. It was found that adsorption was an important factor to achieve high degradation capacity. However, the sonocatalytic activity decreased when adsorption was too intense.

Influence of carbon nanotube concentration and sonication temperature on mechanical properties of HDPE/CNT nanocomposites

ABSTRACT Carbon nanotube (CNT) reinforced high-density polyethylene (HDPE) composites were prepared by a melt mixing procedure. The mechanical properties were analyzed using a central composite design where key factors were CNT concentration and sonication temperature during the sample preparation process. The results indicated that the optimum values were 0.8 wt% for the concentration of CNT and 55°C for the sonication temperature. The samples obtained at optimal conditions were systematically studied. Nanoindentation analysis showed an increase of 43% in Vickers hardness of the nanocomposite when compared to pure polymer. The improvement on the mechanical property is related to changes in the thermo-physical and viscoelastic properties of the nanocomposite.

Functionalization of Carbon Nanotube and Applications

Carbon nanotubes (CNTs) have unique structures, comprising diameters of few nanometers and length of several hundred nanometers, which provides outstanding mechanical, electrical, and thermal properties. Since their discovery in 1991, CNTs have received much attention and are a worldwide research subject due to their wide range of applications as biosensors, drug delivery, electrochemistry, nanoelectronics, superconductors, nanowires, graphene nanoribbons, nanocomposite materials, and so on. The functionalization treatments can enhance the usual CNT poor dispersion in solvents and improve their interactions with other materials, improving their technological application. Then, carbon nanotube is an extremely hot topic, and every day new research papers are published on this subject. This book contains complete and current reviews on CNT topics, such as synthesis, characterization, and application of functionalized CNTs. The characterization of functionalized CNTs is extremely important for determining the real physicochemical properties of the material obtained after functionalization treatments. However, this characterization is rarely addressed in books or review articles. Generally, the functionalization reviews are too wide-ranging, discussing the functionalization of various materials (e.g., nanomaterials), or too specific, analyzing only one functionalization agent (with some specific chemical group, e.g.). This book, however, proposes to discuss the functionalization of one of the most widely used nanomaterials in recent years: carbon nanotube. Thus, the reader will find information on CNT functionalization, using several functionalization agents, in the same book.

Anomalous behavior of thermal stability of amino-carbon nanotube–epoxy nanocomposite:

Carbon nanotube–epoxy nanocomposite was obtained using amino-carbon nanotube and its thermal stability was compared with neat resin. The results showed that at lower temperatures (below 360℃), nanocomposite is more stable than neat resin. However, at higher temperatures (above 380℃), the contrary was observed: neat resin is more stable. In order to understand this anomalous behavior, a complete kinetic study of the cure process was performed. The precure degree of the nanocomposite was higher than that of the neat resin. However, both samples showed virtually the same final cure degree. The cure heat and activation energy were very similar for both samples. Nevertheless, the difference in thermal stability between nanocomposite and neat resin is not related to the cure process. This behavior must be associated with the good adhesion of amino-carbon nanotube–epoxy and to the presence of the functional groups linked to the carbon nanotube surface, especially oxygen molecules.

Effects of octadecylamine functionalization of carbon nanotubes on dispersion, polarity, and mechanical properties of CNT/HDPE nanocomposites

Homogeneous dispersion of carbon nanotubes (CNTs) in polymers has significantly improved their processing and application as nanomaterials. Generally, CNTs tend to agglomerate due to their high aspect ratios and strong van der Waals interaction. Surface functionalization appears to be a solution to this problem. This study presents a controlled dispersion of carbon nanotubes in polyethylene through surface modification using a mixture of concentrated acid and octadecylamine (ODA). CNTs were characterized by Fourier transform infrared, Raman and X-ray photoelectron spectroscopy, and transmission electron microscopy. The results confirmed that carboxyl and alkane groups were successfully introduced on CNT surfaces. The acid- and amine-functionalized carbon nanotubes were dispersed in four solvents with different polarities (water, ethanol, acetone, and xylene) to correlate the degree of dispersion of CNT with their polarity. The results showed that CNT dispersion stability strongly depends on solvent and carbon nanotube polarities after the functionalization step. The nanohardness and tensile tests showed that the addition of CNTs, especially the functionalized with ODA, leaded the polymer harder, increasing its Young’s modulus and tensile strength. However, its toughness and deformation capacity were reduced. The potential applications of CNT-based polymer nanocomposites broaden considerably due to the surface engineering of carbon nanotubes.