A Circular Economy Use of Post-Consumer Polypropylene Packaging for Low Thermal Conductive and Fire-Retardant Building Material Applications

Abstract

Wastes from polypropylene (PP) packages are accumulating every year because it is one of the most widely con-sumed and short lifecycle products. This paper aims to develop low thermal conductive and fire-retardant materials from post-consumer PP (pPP) packages. Ammonium polyphosphate (APP) and hollow glass microsphere (HGM) were further added to improve the fire retardancy and thermal conductivity of pPP. The influence of APP and HGM on the mechanical and thermal properties, fire retardancy and thermal conductivity of pPP were investigated and compared with that of virgin PP (vPP). HGM was constantly added at 5 wt% while the content of APP was varied from 5 to 20 wt%. Experimental results showed that the tensile and flexural strengths were reduced with increasing APP concentrations. A morphological study confirmed the poor interfacial adhesion and debonding of each component during the applied load. Formulations containing APP less than 10 wt% did not show a satisfying fire retardancy rating due to the long self-extinguishing time. Further flame dipping and cotton ignition were observed for these formulations. With 15 and 20 wt% APP, the fire rating was significantly improved from no rating to V-0. The conductive heat transfer coefficient (k) was reduced by the presence of HGM. Based on these results, the formulation with 15 and 20 wt% could be used as a low k, fire-retardant building material. © 2023, Tech Science Press. All rights reserved.