PIN flame retardants were tested to enable fire safety of polypropylene – recycled newspaper fibre composites. Waste fibres can replace glass fibre to provide strength in plastic composites, enabling waste valorisation and also reducing tool wear and processing constraints. Magnesium hydroxide (MDH, Mg(OH)2) was tested as PIN flame retardant, compounded into the polypropylene, on its own 25% and with zinc borate/ATO 5%, in composites of 50% polymer compound – 50% secondary fibres. The MDH alone provided the best fire performance improvement with a decrease in horizontal burning rate of >50% and an increase in LOI (limiting oxygen index) of nearly 25% compared to the PP-fibre composite without FR. The inclusion of the PIN FRs reduced mechanical performance of the PP-fibre composite only slightly or not significantly.
“Recycled Newspaper Fiber/Polypropylene Composites with Inorganic Flame Retardants: Flame Retardant and Mechanical Characteristics”, H. Zaman & R. Khan, Adv. J. Sc. Eng. 2023; 4 (2): 042014.