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

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.

Bioinspired Adenosine Triphosphate as an “All-In-One” Green Flame Retardant via Extremely Intumescent Char Formation

“…When it reaches 400 °C, NH 3 (∼966, ∼1630, and ∼3335 cm –1 ) is dominant in the gaseous state, which means that noncombustible gases begin to flow out of the ATP. This result is clear evidence that noncombustible gases such as CO 2 , H 2 O, and NH 3 , which are produced in large quantities from ATP, play an important role in fuel dilution and the cooling effect during combustion . If ATP continues to be heated above 800 °C, HCN (∼714 and ∼3289 cm –1 ) was released due to the pyrolysis reaction and rearrangement of the adenine ring …”

“…This result is clear evidence that noncombustible gases such as CO 2 , H 2 O, and NH 3 , which are produced in large quantities from ATP, play an important role in fuel dilution and the cooling effect during combustion. 57 If ATP continues to be heated above 800 °C, HCN (∼714 and ∼3289 cm −1 ) was released due to the pyrolysis reaction and rearrangement of the adenine ring. 58 Figure S8 shows the change in the outgassing peak of ATP over time, gradually dominated by ammonia gas and hydrogen cyanide in the atmosphere.…”

Lignin-Based Low-Density Rigid Polyurethane/Polyisocyanurate Foams

“…Though fire properties in rigid foam are generally enhanced via the use of reactive flame retardants, active flame retardants, or flame-retardant coatings, higher density foams and the use of PUR/PIR over PUR formulations will increase fire retardant behavior. This is due to the presence of a more compact burn layer and the presence of more thermally stable PIR bonds, respectively. Since all of our foams were within the low-density range for rigid PUR foams (30–60 kg/m 3 ), the effects of density should not be significant. , This is confirmed by the low correlations between apparent density and fire properties: burn time after flame removal ( r = −0.3), percent weight loss ( r = 0.5), and burn length ( r = −0.5).…”

Fire-retardant and smoke-suppressant rigid polyurethane foam composites

“…Inorganic fillers affect the density of FR-RPUF foam composites (Szycher, 2013). During the formation of FR-RPUF foam cells, solid additive particles may act as heterogeneous nucleation sites, resulting in foam cell size decrease and density increase (Pham, 2020). The addition of solid inorganic fire-retardant partly inherited the expansion of the foam.…”