Flame retardant PP/PA6 blends: A recipe for recycled wastes

Abstract Disposal of plastics in the form of discarded scrap or waste is an environmental nightmare to the developed and under-developing countries. In this sense, modern technologies are every day growing; meanwhile recycling wastes are taking credit for higher performance to pave the way towards a cleaner planet. Recycling of polymer blends is associated with serious complexities in finding appropriate additives acting in each phase or at the interface of non-miscible polymers to attain materials with higher properties. A flame retardant system was designed and intended to play the role of typical recycled flame retardant polypropylene/polyamide (PP/PA6) blends by incorporation of two kinds of talc, sepiolite, and a phosphorus-based flame retardant. First, two types of talcs having different physical properties were added to PA6 in combination with melamine cyanurate (MC) or melamine pyrophosphate (MPP) to find the one acting as a barrier during combustion. Then, high-aspect-ratio talc that appeared more effective in the first-stage survey was then used in combination with MC, MPP and ammonium polyphosphate (APP) together with a compatibilizer for PP/PA6 blend. Then, thermogravimetric analysis (TGA), microcalorimeter of combustion (PCFC) and cone calorimeter measurements were performed to study thermal degradation and flammability behavior. The results are indicative of successful formulation of flame retardant system containing the aforementioned precursors to be intended to the recycled PP/PA6 blends.