Investigations the effects of different fillers on thermal decomposition and fire behaviors of polypropylene based composite materials

In this thesis, the effects of different fillers and flame retardants on the thermal decomposition and the fire behaviors of polypropylene based composite materials especially used in vehicles were investigated. An intumescent flame retardant (IFR) system composed of ammonium polyphosphate and pentaerythritol was added into the polypropylene to enhance the thermal stability and the fire resistance. In addition, montmorillonite clay (MMT), boric acid (BA), walnut shell powder (CKT), hazelnut shell powder (FKT), olive husk powder (ZAT) and different fly ashes (UKs) were used with and without IFR to improve the properties of the composites. A twin screw extruder was used to incorporate the fillers and the flame retardants into the polypropylene. The test samples were produced by using a special mold and an injection machine. The flammability and combustion properties of composites were examined by UL 94, LOI and cone calorimeter tests. The thermal properties of composites were examined by TGA, DSC and thermal conductivity measurements. The examination of the morphological structure of composites was carried out by SEM and FTIR. In addition, tensile, flexural and impact strengths of the polypropylene composites were determined. Apart from the experimental studies, thermal degradation and combustion modelling studies were carried out using FDS (Fire Dynamics Simulator) program. The experimental results showed that % 25 IFR addition can improve the thermal and fire resistances of the polypropylene up to a certain level. Also, it was determined that the uses of MMT, BA, CKT, FKT, ZAT and UKs with IFR can generate further improvements in the thermal and fire resistances without significant adverse effects in the mechanical properties. Meanwhile, CKT, FKT, ZAT and UKs additions without IFR resulted in limited improvements in the thermal and the fire resistances. In addition, it was determined that the modelling results obtained using FDS were partially compatible with the experimental results.