Nanomaterials Thermal Response and CNT Reinforced Polymer Composites: An ab initio Study
Tsafack Tsopbeng, Thierry Tsafack
Yakobson, Boris I
Doctor of Philosophy
Research achievements, both on nanomaterials thermal response and on reinforced polymer composites, are compendiously submitted. Each of the 4 chapters begins with (1) a terse summary of the context, methodology and keys results; segues into (2) the necessity for and the state-of-the-art on the subject with which it concerns itself; then proceeds with (3) the unique contribution the present findings make and the directions the research takes. Each chapter is self-contained and can be perused independently. Chapter 1 covers the relationship between the hole density of boron monolayers and their thermal as well as mechanical properties. The triangular boron sheet (δ6) is found to possess 2.06 and 6.60 times graphene’s lattice and electronic ballistic thermal conductances. Hexagonal sheets such as α and δ5 are predicted to be roughly twice as stiff as graphene. Chapter 2 covers the meaning of the Debye temperature for bulk and low dimensional materials. Two new approaches, one based on the polarization and mode dependent heat capacities and the other based on the mode dependent Debye temperatures, converge to a more precise computation and understanding of the polarization dependent Debye temperature. Chapter 3 covers the thermal properties of carbyne showing and discussing its room-temperature heat capacity at constant volume being 1.6 times that of graphene, a negative coefficient of thermal expansion being 4 times that of graphene, and a much higher thermal conductivity than graphene nanoribbons. Chapter 4 covers the interaction of carbon nanotubes (CNTs) with DGEBA epoxy thermosets for the purpose of identifying strengthening mechanisms. Among doped (Si, B, N), defective (Stone-Wales, three nitrogen atoms surrounding one monovacancy, four nitrogen atoms surrounding one divacancy, monovacancy), functionalized (amine, hydroxyl, carboxyl, oxygen) and different size CNTs, Si-doped, a combination of oxygen and hydroxyl as well as smaller tubes exhibit the strongest indication for mechanical reinforcement.
Thermal properties; Mechanical Properties; Nanomaterials; Densifty functional theory; Molecular Dynamics.