Combustion experiments of aluminum-fluoropolymer composites: A study of additive influences
| dc.contributor.committeeChair | Pantoya, Michelle | |
| dc.contributor.committeeMember | Chaudhuri, Jharna | |
| dc.contributor.committeeMember | Parameswaran, Siva | |
| dc.contributor.committeeMember | Ekwaro-Osire, Stephen | |
| dc.contributor.committeeMember | Green, Micah J. | |
| dc.creator | Kappagantula, Keerti S. | |
| dc.date.available | 2014-09-03T20:10:18Z | |
| dc.date.issued | 2014-08 | |
| dc.description.abstract | Composite energetic materials with nanoscale aluminum particles as fuel have a huge niche in industrial and ordnance applications, due to their numerous advantages over the traditional micron scale counterparts. Fluoropolymers have been gaining popularity over the last decade as a favored oxidizer in these composite energetic systems because of their unique ability to react with the passivating alumina shell present over aluminum particles. The current body of work investigates the tailorability of energetic composites made of nano aluminum (Al) combined with different fluoropolymers, by incorporating different additives into the reactive material. The effect of the proximity of the oxidizer was investigated by performing flame propagation experiments on molybdenum trioxide combined with aluminum particles with and without surface functionalized perfluoro tetradecanoic acid. Results showed that the surface functionalization enhanced the burn rate twice that of non functionalized energetic composite. In order to control the burn velocity by altering their surface functionalizations, three different energetic composites consisting of aluminum (Al) particles with and without surface functionalization, combined with molybdenum trioxide (MoO3) was performed. Perfluoro tetradecanoic (PFTD) and perfluoro sebacic (PFS) acids were used to form organic corona around the aluminum nanopartices. Flame propagation studies revealed that energetic composite made of Al functionalized with PFTD (Al-PFTD) displayed burn velocity 86% higher than Al/MoO3 whereas Al with PFS/MoO3 are almost half of Al/MoO3. Results showed that the fluorine content in the acids and their structural differences contribute to difference in burn velocity. Impact sensitivity of Al combined with polytetrafluoroethylene (PTFE) was investigated by incorporating chemically similar but structurally different additives into the energetic matrix, namely graphene, carbon nanotubs and amorphous nanocarbon spheres. Burning of the composites was studied under an insult scenario using a drop weight apparatus. Results showed that composites consisting of carbon nanotubes were significantly more sensitive to impact ignition compared to those with graphene. A unique diagnostic technique, combining multiwavelength pyrometry and high speed infra-red imaging was developed to measure the temperatures in a combustion cloud post material ignition. Temperature resolved thermal images of Al combined with copper oxide (Al/CuO) and Al/PTFE embedded with different additives were analyzed. Temperatures were plotted as a function of distance from the point of ignition such that inflection points distinguishing temperature gradients provide an indication of the range of the thermal influence. Gas generation and heat of combustion were identified as the principal factors affecting temperature fields: greater gas generation in addition to condensed phase products promoted higher temperatures in the far field. | |
| dc.format.mimetype | application/pdf | |
| dc.identifier.uri | http://hdl.handle.net/2346/58903 | |
| dc.language.iso | eng | |
| dc.rights.availability | Unrestricted. | |
| dc.subject | Nanoparticles | |
| dc.subject | Combustion | |
| dc.subject | Aluminum | |
| dc.subject | Fluoropolymers | |
| dc.subject | Composites | |
| dc.subject | Diagnostics | |
| dc.subject | Flame speed | |
| dc.subject | Temperature | |
| dc.title | Combustion experiments of aluminum-fluoropolymer composites: A study of additive influences | |
| dc.type | Dissertation | |
| thesis.degree.department | Mechanical Engineering | |
| thesis.degree.discipline | Mechanical Engineering | |
| thesis.degree.grantor | Texas Tech University | |
| thesis.degree.level | Doctoral | |
| thesis.degree.name | Doctor of Philosophy |