Thermal Properties and Fire Retardancy of Polypropylene/Wood Flour Composites Containing Eco-friendly Flame Retardants

Abstract

Thermal properties and the flame retardancy of polypropylene/wood flour (PP-WF) composite were improved by adding aluminum hydrogen phosphonate (AHP) and triphenyl phosphate (TPP) flame retardants. PP-WF composites containing 30 wt% of AHP and 30 wt% of TPP achieved UL-94 HB standard with the horizontal burning rate of 20.8 mm/min and of 11.5 mm/min, respectively. Thermal properties of PP-WF composite with and without flame retardant, as well as the interaction between PP-WF and flame retardant were investigated through TGA analysis. The flame retardant mechanism is mainly in condensed phase for AHP and in gas phase for TPP. The residual char after the decomposition of PP-WF/AHP composite was analyzed by FTIR to understand how the formation of char affected on the flame retardancy and thermal stability PP-WF composite.