Performance of Lammelar Zirconium Phosphate as Flame Retardant for Post-Consumer Poly (Ethylene Terephthalate)

Due to the damage caused to human lives and financial losses, there is a global concern about materials that offer greater fire resistance. This research investigated the action of the lammelar zirconium phosphate (ZrP) as flame retardant (FR) when added in post-consumer poly(ethylene terephthalate) named as rPET. ZrP was tested alone and in combination with aluminum hydroxide [Al(OH)3] and sodium hypophosphite [NaPO2H2·H2O]. PET beverage bottles were collected, washed, shredded as flakes and ground. Firstly, masterbatches of rPET/FR (80/20 wt./wt.%) were processed in co-rotating twin-screw extruder, processing window 120 - 260˚C, at 300 rpm. The addition of each flame retardant altered the domain distribution curve and relaxation time of rPET. The presence of flame retardant did not modify the X-ray diffraction pattern of rPET. Calorimetric data indicated that the flame retardants increased the cooling crystallization temperature, while their effects on melting temperature and degree of crystallization varied depending on the specific retardant system. Rheology showed that storage and loss moduli varied with the kind of flame retardant and that rPET changed the behavior from Newtonian to pseudoplastic. Finally, composites of rPET/masterbatch (75/25 wt./wt.%) were processed in a mixing chamber, at 260˚C, 60 rpm for 6 minutes. Compression moulding specimen was prepared for flammability test. Field emission scanning electron microscopy and energy dispersive spectroscopy revealed that ZrP nanoparticles were better dispersed and distributed in the specimen when compared to the microparticles of Al(OH)3 and NaPO2H2·H2O. ZrP showed the best dripping speed and flame extinguishing time.