Synergistic effect of carbon nanotube on improving thermal stability, flame retardancy, and electrical conductivity of poly(butylene succinate)/piperazine pyrophosphate composites

Abstract

Biodegradable poly (butylene succinate) (PBS) is considered as promising material for replacing conventional nondegradable polymers in various engineering fields, but its applications are limited by inherent flammability and low electrical conductivity. In this study, the synergistic effect of carbon nanotube (CNTs) on improving thermal stability, flame retardancy and electrical conductivity of poly(butylene succinate)/piperazine pyrophosphate (PBS/PAPP) composites was investigated. Thermogravimetric analysis (TGA) demonstrated that the addition of CNTs could improve the thermal stability of PBS/PAPP composites, where the maximum mass loss temperature (Tmax) of PBS/18PAPP-2CNT increased by 9.1 o C in comparison with that of PBS/20PAPP. Meanwhile, PBS/18PAPP-2CNT exhibited the optimal flame retardancy with limited oxygen index (LOI) of 30.1%, V0 rating in UL-94 vertical burning test and 79.6% reduction on the peak of heat release rate (PHRR) in cone calorimeter test. The synergistic effect of CNTs and PAPP was beneficial to form high-quality char layer, resulting in the enhanced flame retardancy of PBS. Furthermore, the CNTs could improve the electrical conductivity of PBS/PAPP composites with low percolation threshold of 1.75 wt%, which was ascribed to the "volume excluded effect" of PAPP. Thus, the current work provided an efficient strategy to prepare multifunctional PBS composites to meet various engineering applications.