Burning behavior analysis of polypropylene composite containing poly-siloxane encapsulated expandable graphite

Expandable graphite (EG) was encapsulated by a poly-siloxane ([email protected]) and introduced into polypropylene (PP) composite as flame retardant additives. Compared with that of PP/EG composite, PP/[email protected] composite achieved the V-0 rating with a loading of 25 wt.%. Additionally, the total heat release of PP/[email protected] composite was decreased by 42% compared with that of control PP in the cone calorimeter test. To investigate the burning behavior of PP/[email protected], a burning rate measurement was designed and finite element analysis was introduced to evaluate influences brought by char volume and shape formed by EG. The temperature field was calculated among EG and [email protected] expanding in the PP matrix. Additionally, Fourier transforms infrared spectroscopy and scanning electron microscope observation were operated to investigate the char residues. It was proposed that the outstanding flame retardancy brought by [email protected] was owing to the compact and dense char.