ANALYSIS OF VARIOUS MECHANICAL PROPERTIES OF BORON NITRIDE NANOTUBES BASED NANOCOMPOSITES

Abstract

Boron nitride nanotubes (BNNTs), are firstly manufactured in 1995, which are structurally similar to carbon nanotubes (CNTs) having alternate boron and nitrogen atoms in place of carbon atoms. Besides their structure, mechanical and thermal properties, BNNTs are very similar to CNTs. However, BNNTs have higher oxidation resistance than CNTs and also they are electrically isolated. Therefore, they are predictably more suitable fillers for the fabrication of mechanical and thermal enhanced polymeric composites, and can also preserve the electrical isolation of the polymer matrix. In this study, Polymethyl methacrylate (PMMA) - boron nitride nanotube (BNNT) composites were prepared using various methods. Mechanical properties of PMMA-BNNT composites were investigated as a function of nanotube loading. The nanotubes used in the composites were developed by reacting ammonia gas and powdered mixture of elemental boron and iron oxide. X-ray diffraction (XRD) analysis justified the predominant hexagonal boron nitride in end manufactured product. The primary objective of this work is to study the dynamic behaviour of single walled Boron nanotube composite and focus on their applications as mass sensors. The computational methods employed in this report include: Continuum Mechanics (CM) and FEM.First of all, Continuum mechanics(CM) approach has been used to study the effect of mass variations on the single walled nanotube composites. The effects of different boundary conditions of the BNNT on the computed frequencies have been identified for possible applications in vibrating mass sensors or electromechanical resonators(EMR). Cantilever boundary conditions have been explored for femtograms scale mass. The excitations are due to the change in mass as well as parametric excitations.. It has been observed that the mass sensitivity of single walled nanotubes can reach to 10-18 grams. Applications of nanocomposite based mass sensors have been explored. It has been shown that this type of mass sensing systems can be utilized for monitoring of acetone level in breath for monitoring diabetes. Based on the stiffness variation found between normal and cancerous cell it is revealed that early detection of cancer can be made possible. Apart from the applications in the medicine field, it is shown that this system is also used for sensing mass of gold, silver and chromium atoms. The use of nanocomposite based mass sensors for sensing zeptogram scale mass has been investigated. The shift in the resonant frequency due to the change in the attached mass has been used as a parameter for exploring composite as a bio nano mass sensor.