Effective Phosphorus/Phosphorus-Nitrogen Fire Retardants Applied to Biocomposites Based on Polypropylene-Wood Flour: Flammability, Thermal Behavior, and Mechanical Properties

摘要

By adding diammonium phosphate (DAP) or aluminum diethyl phosphinate (OP) as flame retardants, flame retardancy of composites based on polypropylene and wood flour (PP-WF) improved significantly. A loading of 25 wt% DAP achieved a UL-94 V-0 rating as well as LOI value of 29%, which increased by 52.6% compared with that of the PP-WF composite alone. A 30 wt% OP loading provided a rating of UL-94 HB standard, and achieved LOI value of 28%. Meanwhile, the PP-WF composite without flame retardant, completely burned to the sample holder clamp with low LOI value (19%). Thermal properties of the PP-WF composite with and without DAP and OP flame retardants, were investigated using TGA and DSC. Flame retardant performance was also studied, through the morphology and chemical structure of residual char by TGA, FTIR, SEM, and XPS analyses. There was interaction between DAP and the composite, which played a key role in maintaining mechanical properties of the material.