Raghavan Prasanth

Eco-friendly Polymer Nanocomposite—Properties and Processing

This chapter mainly reviews the concept, properties and processing, and design method of the eco-friendly polymer nanocomposite (EPN), which is generally biodegradable and renewable. The major attractions of EPN are that they are environmentally friendly, sustainable, and degradable. These polymer composites can be easily composted or disposed without harming the environment. Some efforts have been made on attaining biodegradable reinforcing fillers giving improved performance of composites. Another concern is focused on employing recyclable synthetic fibers with thermoplastic composites to reduce the waste of fillers, and also some research is devoted to reusing or recycling the whole composites for the similar purpose. Simultaneously, people also would like to make composites manufactured with traditional production process become eco-friendly by extra reprocessing. Throughout the stages of development––design, appraisal, manufacture, use, reuse–recycling, and disposal––researchers are supposed to be fully engaged in reducing waste as much as possible, keeping in mind the environment all the time. A series of natural or synthetic materials have been used, such as cellulose, thermoplastic starch, etc. The challenge posed by eco-friendly composites also needs considerable attention in terms of poor bonding between matrix and fillers, loose control of fiber orientation, and difficulty in shaping nanoscale particles.

Advances in Lithium-Ion Battery Technology Based on Functionalized Carbon Nanotubes for Electrochemical Energy Storage

Increasing demand for higher energy density and higher-power energy-storage devices from the portable power market and the automobile and telecommunication industries have led to the search for novel materials for electrodes or electrolytes that offer higher capacities and energy densities and better performance than the electrochemical energy-storage devices available today. It is recognized that these requirements cannot be met solely by the capabilities of conventional systems and energy materials. Nanomaterials, a cutting-edge technology, can serve as an alternative to traditional materials. Among these, carbon nanotubes (CNTs) and their hybrid nanostructures have been extensively studied in electrochemical energy storage devices such as lithium-ion batteries (LIBs), supercapacitors, solar cells, and fuel cells as ideal electrode materials. This is because of their unique, one-dimensional (1D) tubular structure and high surface area, aspect ratio, chemical stability, electrical, and thermal conductivities, along with their extremely high mechanical strength. Studies show that CNTs are capable of greatly improving the electrochemical characteristics of energy-storage systems, with enhanced energy conversion and storage capacities. This chapter discusses recent advances in lithium-ion/air batteries based on CNTs and their functionalized derivatives for electrochemical energy storage.

Application of Carbon Nanotubes for Resolving Issues and Challenges on Electrochemical Capacitors

In electrochemical capacitors electrode is the key factor to determine the energy density and power density; hence the selection of electrode materials is the most crucial part. The specific energy of commercial supercapacitors is limited to 5–6 Wh kg−1, whereas for batteries the lower limit is 35–40 Wh kg−1. In this chapter, the type of electrochemical capacitors, the storage principles, and the characteristics of composite electrode based on carbon nanotubes and carbon-based materials, transition metal oxides, and conducting polymers are briefly discussed. The composites combine the large pseudocapacitance with the fast charging/discharging double-layer capacitance and excellent mechanical properties of the carbon nanotubes. Most of the commercially available devices use carbon electrodes and organic electrolytes, and research efforts have been done to increase the specific capacitance of supercapacitor electrodes based on carbon nanotubes. Composite electrodes based on carbon nanotubes exhibit excellent electronic conductivity, electrochemical charge-storage properties, fast charge/discharge switching, and specific power making them promising electrode materials for high-power supercapacitors due to their unique properties of carbon nanotubes.

Eco-Friendly Polymer-Layered Silicate Nanocomposite–Preparation, Chemistry, Properties, and Applications

This chapter aims at exploring the revolutionary field of nanotechnology and some of its promising aspects in polymer nanocomposites in view of preparation, characterization, materials properties, and processing of polymer layered silicate nanocomposites. These materials are attracting considerable interest in polymer science research. Polymer layered silicate nanocomposites are an important class of hybrid, organic/inorganic materials with substantially improved mechanical, thermal, and thermomechanical properties in comparison to pristine polymers. In addition, they also show superior ultraviolet (UV) as well as chemical resistance and are widely being investigated for improving gas barrier and flame retardant properties. Hectorite and montmorillonite are among the most commonly used smectite-type layered silicates for the preparation of polymer–clay nanocomposites. Smectites are a valuable mineral class for industrial applications due to their high cation exchange capacities, surface area, surface reactivity, adsorptive properties, and, in the case of hectorite, high viscosity and transparency in solution. A wide range of polymer matrices are explored for the preparation of polymer–clay nanocomposites, however, this chapter deals with special emphasis on biodegradable polymers––cellulose and natural rubber. Also, the chapter describes the common synthetic techniques in producing polymeric layered silicate nanocomposites, its properties, and applications.

Functionalization of Carbon Nanotubes and Their Polyurethane Nanocomposites

Carbon nanotubes (CNTs) exhibit a unique combination of electrical, mechanical, and magnetic properties as well as nanometer-scale diameter and high aspect ratio, which make them an ideal reinforcing agent for high-strength polymer composites. However, there is still challenge to achieve the simple and economical method for improving the dispersion and solubilization of CNTs. To improve the dispersion of CNTs, several approaches have been applied by using covalent and noncovalent functionalization methods. Herein, in particular, we focused on CNT functionalization using dendritic polymer and click chemistry approach. The impact of CNT dispersion on the property improvement of composite materials is discussed. In particular, the polyurethane block copolymer-CNT composites are discussed in details.