Study on Char Structure of Intumescent Flame-Retardant Polypropylene

The structure and properties of the char of intumescent flame retardant polypropylene (IFR-PP) have been studied by cone calorimeter, scanning electron microscope (SEM) and differential scanning calorimeter (DSC). Charring tendency analysis indicates IFR-PP is more likely to form a thick and homogenous char at low heat flux than that at higher heat fluxes. The SEM study indicates different char structures are formed at different stages. DSC analysis studies thermal stability of IFR-PP. Theoretical analysis of intuemscent charring shows when intumescent velocity increases, the heat diffusing into the underlying material will decrease if the thermal diffusivity of the material keeps constant.

Keywords:

• Cone calorimeter
• DSC
• Intumescent char
• Intumescent flame retardant
• Polypropylene

ACKNOWLEDGMENTS

The authors gratefully acknowledge the financial support of China NSFC Funds (No. 50176021) and China Special Doctorate Funds for Colleges and Universities.