Authors:

Varunavi Kaveri Raghuraman

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About Paper:

Polymer-bonded explosives (PBXs) must be engineered to deliver high energy output while remaining stable and predictable under thermal, mechanical, and environmental stress. Inconsistencies in pellet microstructure, such as voids, nonuniform binder distribution, or porosity, can lead to unpredictable initiation, poor performance, or dangerous handling conditions. New hydroxyl-terminated polybutadiene (HTPB) molding powders reduce the need for toxic solvents in traditional manufacturing processes and cure thermally over time. Storing the powders at cold temperatures could extend the processing lifetime, yet the effect of storage on final pellet properties is not understood. This study aims to understand how storing partially cured HTPB molding powder at different temperatures and varying durations affects the microstructural and mechanical properties of the resulting PBX pellets. Molding powders were prepared using partially cured HTPB with a precure time of either 2 or 4 hours. Both powders were stored in refrigerator (0°C) or freezer (-17°C) conditions for 24, 48, or 168 hours. After storage, the powders that were precured for 4 hours were immediately pressed, while the powders that were precured for 2 hours were thermally cured for an additional 2 hours and then pressed. Optical profilometry, Archimedes density testing, and compression testing were used to assess surface uniformity, bulk density, and mechanical integrity, respectively. A rheometer with parallel plate geometry and temperature control was used to study the degree of crosslinking and processing time of HTPB. This research identified storage times and temperatures extending molding powder processability and investigated how precure interruptions affect final PBX properties. Keywords: [no keywords provided]

Source:

Purdue University / 2025

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Co-authors:

Varunavi Kaveri Raghuraman