Comprehensive Investigation of the Behavior of Polyurethane Foams Based on Conventional Polyol and Oligo-Ester-Ether-Diol from Waste Poly(ethylene terephthalate): Fireproof Performances, Thermal Stabilities, and Physicomechanical Properties
Chi T. Pham, Binh T. Nguyen, T. Hien Nguyen, Soo‐Jung Kang, Jinhwan Kim, Pyoung‐Chan Lee, DongQuy Hoang
Abstract
The chemical recycling of postconsumer poly(ethylene terephthalate) (PET) bottles to produce highly thermally stable polyurethane foam (r-PUF) with excellent flame-retardant (FR) performance could be applied on an industrial scale to create a sustainable recycling industry. The advantage of oligo-ester-ether-diol obtained from waste PET glycolysis is its application in r-PUF, generating a durable foam with excellent fire resistance at rather low loadings of phosphorus-nitrogen FRs (P-N FRs), especially in high moisture environments. Compared to polyurethane foam from commercial polyol (c-PUF), r-PUF is notably more thermally stable and efficient in terms of flame retardancy, even without adding FRs. By incorporating 15 php diammonium phosphate (DAP) as a P-N FR, r-PUF/DAP self-extinguished 5 s after the removal of the 2nd flame application with a limited oxygen index value of 24%. However, for c-PUF, a much higher DAP (30 php) loading did not exhibit any rating in the vertical burning test. The aromatic moiety in the oligo-ester-ether-diol structure strongly enhanced the compressive strength and thermal stability. The positive outcomes of this study also confirmed that the r-PUF/DAP prepared from oligo-ester-ether-diol not only satisfied the fire safety requirements of polymer applications but also contained a high percentage of postconsumer PET, which could help reduce the amount of recycled polymer materials and improve waste management.