Combustion enhancement of hydroxyl-terminated polybutadiene by doping multiwall carbon nanotubes

Hydroxyl-terminated polybutadiene (HTPB) is extensively used in propulsion; however, it's trapped in low regression rate, partly related to poor thermal transfer from combustion. Carbon nanotubes (CNT) act as an energy transfer media, potentially accelerating the heat transfer and combustion performance of HTPB. Herein, multiwall CNT (MWCNT)/HTPB composites were prepared by dispersing MWCNT and surfactant into HTPB and toluene solvent through ball milling . Low MWCNT content (≤1%) promoted combustion, and excess MWCNT (≥2%) depressed, despite MWCNT shifting the HTPB-O 2 reaction to higher temperatures. (0.5%, 1%, 2% and 3%) MWCNT/HTPB composites reinforced the instantaneous regression rate by 11.2%, 31.6%, −21.3%, and −39.7% at Gox  = 365 kg/m 2 ·s; by 27.0%, 25.0%, −26.4%, and −36.6% at Gox  = 150 kg/m 2 ·s; while strengthened the average regression rate by 0.9%, 8.5%, −17.4%, and −36.7% at Gox  = 365 kg/m 2 ·s; and by 5.4%, 8.9%, −8.3%, −22.6% at Gox  = 100 kg/m 2 ·s. Specifically, the optimal MWCNT level was 1%, as demonstrated by the optimized reinforced thermal conductivity and slightly reduced energy release, since excessive MWCNT (>2%) hinders combustion through heat dissipation, high viscosity of the melting layer, low energy release and an attached carbon layer on the burning surface blocking the energy transfer.