Parametric analysis of flammability performance of polypropylene/kenaf composites

With the high amount of flame retardant content required to produce acceptable levels of fire retardancy for natural fibre composites, it is a challenge to achieve a balance between the mechanical and the flammability properties of these composites because often the fire retardants adversely affect the mechanical performance. In this research, we have used the Taguchi design of experiments approach using standard L₉(3⁴) orthogonal array to develop the favourable flame retardant combination for polypropylene/kenaf composites. The parametric responses have been analysed to maximise the fire performance index (FPI) obtained under the cone calorimeter testing. Furthermore, Underwriters Laboratory Vertical burning (UL-94 V) tests have also been conducted to take into the account the flame extinguishing ability under sustained combustion for evaluating the desired parametric combination. The results indicate that the maximum levels of intumescent flame retardant ammonium polyphosphate (APP) content and synergistic natural flame retardant additive (wool) content are the most significant influencing factors in the development of desired flame retardant combination. The compatibiliser and antioxidant contents have been observed to be relatively less influential in FPI evaluation and an increased level of maleic anhydride-grafted polypropylene compatibiliser is found to be adversely affecting to the sustained combustion under UL 94 V tests.