On the combustion of heterogeneous AP/HTPB composite propellants: A review

Agglomeration and combustion characteristics of solid composite propellants containing aluminum-based alloys

A new micromechanical formulation based on a unit cell model is developed to predict the effective thermal conductivities of carbon nanotube (CNT)-shape memory polymer (SMP) nanocomposites. Model predictions considering interfacial thermal resistance between the CNT and SMP, agglomerated state of CNTs into the SMP matrix and CNT non-straight shape are in reasonable agreement with the experiment reported in the literature. It is found that the CNT agglomeration must be removed to obtain a maximum level of thermal conductivities of SMP nanocomposites. The effects of volume fraction, diameter, cross-section shape, arrangement type and waviness factors of CNTs as well as interfacial thermal resistance on the axial and transverse thermal conductivities of aligned CNT-reinforced SMP nanocomposites are extensively investigated. The results show that the alignment of CNTs into the SMP nanocomposites along the thermal loading can be an efficient way to dissipate the heat. When the CNT waviness increases, a nonlinear decrease in the axial thermal conductivity is occurred, however, the nanocomposite thermal conductivity along the transverse direction quickly rises. It is observed that the interfacial thermal resistance, cross-section shape and arrangement type of CNTs do not affect the axial thermal conductivity of CNT-SMP nanocomposites. But, the interfacial thermal resistance can play a key role in the transverse nanocomposite thermal conductivity. The present fundamental study is very important for understanding the thermal conducting behavior of CNT-SMP nanocomposites which may have a wide range of applications in temperature sensing elements and biological micro-electro-mechanical systems.

Thermal conductivity of shape memory polymer nanocomposites containing carbon nanotubes: A micromechanical approach

Military systems have become more complex, and the development of future advanced materials for defence applications has received much attention. Nanocellulose has been identified as a ‘super versatile material’ that will become a replacement material for many applications including in the military. Nanocellulose can be synthesized from discarded fibers that are left over from forestry and agricultural waste that can be transformed into high-value products. Thanks to its interesting properties, comprising low thermal expansion coefficient, high aspect ratio, high crystallinity, and good mechanical and optical properties, nanocellulose has emerged as a new material class for high end military products such as bulletproof vests, fire-retardant materials, as a component of propellants and filtration materials, and in textile, electronic and energy products. Therefore, in this review, current and future applications of nanocellulose in the military are critically discussed. This review is intended to impart to readers some of the excitement that currently surrounds nanocellulose research, and it's fascinating chemical and physical properties and applications in the military.

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Nanocellulose: the next super versatile material for the military

The effects of packing structure on the effective thermal conductivity of granular media: A grain scale investigation

An effective method to embed catalyst on AP and its effect on the burn rates of aluminized composite solid propellants

Estimation of burning characteristics of AP/HTPB composite solid propellant using a sandwich model

Combustion of Ammonium Perchlorate monopropellant: Role of heat loss

Thermal conductivity estimation of high solid loading particulate composites: A numerical approach

The present study reports the development of a novel technique to quantify binder melt on the surface of the propellant. Non-aluminized AP-HTPB propellants of 86% particulate loading are used to illustrate the technique. Elemental maps of unburnt and extinguished propellant surface are obtained using EDS (Energy Dispersive Spectroscopy). Overlap between the elements is identified and the elemental maps are processed to calculate AP and binder area exposed in unburnt and extinguished samples. The AP area exposed is found to be around 72.3% and 63.3% for unburnt and extinguished samples, respectively, indicating a reduction in AP exposed area with extinguished samples. This has been attributed to the binder melt discussed in literature but never quantified. Simulations have been carried out to analyze and understand the effects of this binder melt. A random packing algorithm is used to simulate propellant packs. Also, a methodology to account for binder melt layer is introduced and is used to capture AP exposed areas. Effect of binder melt in propellants with different solid loading and varying particle size is discussed. It is shown that fine AP particles are more prone to being covered by binder melt than the coarse AP particles. A possible explanation to the behavior of plateau burning propellants observed in literature has been provided through this analysis.

Chaitanya Vijay

Papers

An effective method to embed catalyst on AP and its effect on the burn rates of aluminized composite solid propellants

Estimation of burning characteristics of AP/HTPB composite solid propellant using a sandwich model

Combustion of Ammonium Perchlorate monopropellant: Role of heat loss

Thermal conductivity estimation of high solid loading particulate composites: A numerical approach

Binder melt: Quantification using SEM/EDS and its effects on composite solid propellant combustion