Use of manufacture residue of fluidized-bed catalyst-cracking catalyzers as flame retardant in recycled high density polyethylene

The Municipal Company of Urban Cleaning uses plastic lumber to manufacture urban furniture items, whose process generates a post industrial waste scrap that is recycled once again. The Fabrica Carioca de Catalisadores produces catalysts for oil cracking in fluidized bed. This production process creates an inorganic solid residue with prospective flame retardant property in polymeric materials. This inorganic residue is currently sent to licensed landfill. The goal of the present work was to test the use of this inorganic solid waste from the manufacture of fluidized-bed catalytic cracking catalysts as flame retardants agent in polymer–matrix composites of rHDPE. The materials were processed in a Haake internal mixer, and the rHDPE/inorganic residue composites were compounded in the 100/0, 80/20, 60/40 and 40/60 proportions, by weight percentage. The composite materials were characterized by: flammability tests, tensile tests; TG/DTG, DSC and SEM. The results of the horizontal firing tests performed clearly showed that the incorporation of inorganic residue into the polymer material fostered the increase on fire resistance. The TG curves showed that the thermal decomposition of the material occurred between 480 and 500 °C. The DSC curves of the residue showed a characteristic peak of alumina dehydration, below 300 °C. The tensile test results demonstrated that when 20% residue was added, the Young's modulus of the rHDPE increased by about 17% but the tensile strength was similar to rHDPE. The incorporation of inorganic particles into the polymeric matrix resulted in a change in the behavior of the material – from ductile to brittle – as observed by SEM micrographs.