Oxidative and non-oxidative degradation of a TDI-based polyurethane foam: volatile product and condensed phase characterisation by FTIR and solid state 13C NMR spectroscopy

D. Allan; J. Daly; J.J. Liggat

doi:10.1016/j.polymdegradstab.2018.12.027

Oxidative and non-oxidative degradation of a TDI-based polyurethane foam

volatile product and condensed phase characterisation by FTIR and solid state ¹³C NMR spectroscopy

D. Allan, J. Daly, J.J. Liggat

Research output: Contribution to journal › Article

1 Citation (Scopus)

Abstract

The oxidative and non-oxidative degradation behaviour of a flexible polyurethane foam, synthesised from toluene diisocyanate and a polyether polyol, is reported. Both toluene diisocyanate and diaminotoluene were identified as major products under non-oxidative conditions, which indicates that the urethane linkages are degrading by two competing degradation mechanisms. Degradation of the urethane linkage by a depolymerisation reaction to yield toluene diisocyanate and polyol is proposed to occur initially. In addition, the atmospheric pressure conditions favour the degradation of the urethane linkages via a six-membered ring transition state reaction to form diaminotoluene, carbon dioxide and alkene terminated polyol chains. Solid-state ¹³C NMR spectroscopy and elemental analysis of the residues indicates that at temperatures above 300°C ring fusion of the aromatic components within the foam occurs, and this leads to a nitrogen-containing carbonaceous char which has a complex aromatic structure. It is proposed that under the confined conditions of the degradation the aromatic nitrogen-containing species, such as toluene diisocyanate and diaminotoluene, undergo secondary reactions and ring fusion to yield a complex char structureUnder oxidative conditions, degradation, including ring fusion, occurs at a lower temperature than under non-oxidative conditions. Neither toluene diisocyanate nor diaminotoluene were observed as major degradation products. The polyol is observed to undergo thermo-oxidative degradation at much lower temperatures than purely thermal degradation. As a consequence, the depolymerisation reaction via the six-membered ring transition state is limited in extent and diaminotoluene is not evolved. The absence of toluene diisocyanate is proposed to be a result of this species undergoing oxidative degradation reactions which lead to it being incorporated into the char.

Original language	English
Pages (from-to)	57-73
Number of pages	17
Journal	Polymer Degradation and Stability
Volume	161
Early online date	24 Dec 2018
DOIs	https://doi.org/10.1016/j.polymdegradstab.2018.12.027
Publication status	Published - 1 Mar 2019

Fingerprint

polyurethane foam

Toluene 2,4-Diisocyanate

Nuclear magnetic resonance spectroscopy

Polyurethanes

Foams

diisocyanates

degradation

solid state

Degradation

nuclear magnetic resonance

Toluene

toluene

products

Polyols

spectroscopy

urethanes

Urethane

linkages

rings

depolymerization

Keywords

polyurethane foam
TDI
solid state NMR
condensed phase
thermal degradation
oxidation

Cite this

Allan, D., Daly, J., & Liggat, J. J. (2019). Oxidative and non-oxidative degradation of a TDI-based polyurethane foam: volatile product and condensed phase characterisation by FTIR and solid state ¹³C NMR spectroscopy. Polymer Degradation and Stability, 161, 57-73. https://doi.org/10.1016/j.polymdegradstab.2018.12.027

Allan, D. ; Daly, J. ; Liggat, J.J. / Oxidative and non-oxidative degradation of a TDI-based polyurethane foam : volatile product and condensed phase characterisation by FTIR and solid state ¹³C NMR spectroscopy. In: Polymer Degradation and Stability. 2019 ; Vol. 161. pp. 57-73.

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abstract = "The oxidative and non-oxidative degradation behaviour of a flexible polyurethane foam, synthesised from toluene diisocyanate and a polyether polyol, is reported. Both toluene diisocyanate and diaminotoluene were identified as major products under non-oxidative conditions, which indicates that the urethane linkages are degrading by two competing degradation mechanisms. Degradation of the urethane linkage by a depolymerisation reaction to yield toluene diisocyanate and polyol is proposed to occur initially. In addition, the atmospheric pressure conditions favour the degradation of the urethane linkages via a six-membered ring transition state reaction to form diaminotoluene, carbon dioxide and alkene terminated polyol chains. Solid-state 13C NMR spectroscopy and elemental analysis of the residues indicates that at temperatures above 300°C ring fusion of the aromatic components within the foam occurs, and this leads to a nitrogen-containing carbonaceous char which has a complex aromatic structure. It is proposed that under the confined conditions of the degradation the aromatic nitrogen-containing species, such as toluene diisocyanate and diaminotoluene, undergo secondary reactions and ring fusion to yield a complex char structureUnder oxidative conditions, degradation, including ring fusion, occurs at a lower temperature than under non-oxidative conditions. Neither toluene diisocyanate nor diaminotoluene were observed as major degradation products. The polyol is observed to undergo thermo-oxidative degradation at much lower temperatures than purely thermal degradation. As a consequence, the depolymerisation reaction via the six-membered ring transition state is limited in extent and diaminotoluene is not evolved. The absence of toluene diisocyanate is proposed to be a result of this species undergoing oxidative degradation reactions which lead to it being incorporated into the char.",

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Allan, D, Daly, J & Liggat, JJ 2019, 'Oxidative and non-oxidative degradation of a TDI-based polyurethane foam: volatile product and condensed phase characterisation by FTIR and solid state ¹³C NMR spectroscopy', Polymer Degradation and Stability, vol. 161, pp. 57-73. https://doi.org/10.1016/j.polymdegradstab.2018.12.027

Oxidative and non-oxidative degradation of a TDI-based polyurethane foam : volatile product and condensed phase characterisation by FTIR and solid state ¹³C NMR spectroscopy. / Allan, D.; Daly, J.; Liggat, J.J.

In: Polymer Degradation and Stability, Vol. 161, 01.03.2019, p. 57-73.

Research output: Contribution to journal › Article

TY - JOUR

T1 - Oxidative and non-oxidative degradation of a TDI-based polyurethane foam

T2 - volatile product and condensed phase characterisation by FTIR and solid state 13C NMR spectroscopy

AU - Allan, D.

AU - Daly, J.

AU - Liggat, J.J.

PY - 2019/3/1

Y1 - 2019/3/1

N2 - The oxidative and non-oxidative degradation behaviour of a flexible polyurethane foam, synthesised from toluene diisocyanate and a polyether polyol, is reported. Both toluene diisocyanate and diaminotoluene were identified as major products under non-oxidative conditions, which indicates that the urethane linkages are degrading by two competing degradation mechanisms. Degradation of the urethane linkage by a depolymerisation reaction to yield toluene diisocyanate and polyol is proposed to occur initially. In addition, the atmospheric pressure conditions favour the degradation of the urethane linkages via a six-membered ring transition state reaction to form diaminotoluene, carbon dioxide and alkene terminated polyol chains. Solid-state 13C NMR spectroscopy and elemental analysis of the residues indicates that at temperatures above 300°C ring fusion of the aromatic components within the foam occurs, and this leads to a nitrogen-containing carbonaceous char which has a complex aromatic structure. It is proposed that under the confined conditions of the degradation the aromatic nitrogen-containing species, such as toluene diisocyanate and diaminotoluene, undergo secondary reactions and ring fusion to yield a complex char structureUnder oxidative conditions, degradation, including ring fusion, occurs at a lower temperature than under non-oxidative conditions. Neither toluene diisocyanate nor diaminotoluene were observed as major degradation products. The polyol is observed to undergo thermo-oxidative degradation at much lower temperatures than purely thermal degradation. As a consequence, the depolymerisation reaction via the six-membered ring transition state is limited in extent and diaminotoluene is not evolved. The absence of toluene diisocyanate is proposed to be a result of this species undergoing oxidative degradation reactions which lead to it being incorporated into the char.

AB - The oxidative and non-oxidative degradation behaviour of a flexible polyurethane foam, synthesised from toluene diisocyanate and a polyether polyol, is reported. Both toluene diisocyanate and diaminotoluene were identified as major products under non-oxidative conditions, which indicates that the urethane linkages are degrading by two competing degradation mechanisms. Degradation of the urethane linkage by a depolymerisation reaction to yield toluene diisocyanate and polyol is proposed to occur initially. In addition, the atmospheric pressure conditions favour the degradation of the urethane linkages via a six-membered ring transition state reaction to form diaminotoluene, carbon dioxide and alkene terminated polyol chains. Solid-state 13C NMR spectroscopy and elemental analysis of the residues indicates that at temperatures above 300°C ring fusion of the aromatic components within the foam occurs, and this leads to a nitrogen-containing carbonaceous char which has a complex aromatic structure. It is proposed that under the confined conditions of the degradation the aromatic nitrogen-containing species, such as toluene diisocyanate and diaminotoluene, undergo secondary reactions and ring fusion to yield a complex char structureUnder oxidative conditions, degradation, including ring fusion, occurs at a lower temperature than under non-oxidative conditions. Neither toluene diisocyanate nor diaminotoluene were observed as major degradation products. The polyol is observed to undergo thermo-oxidative degradation at much lower temperatures than purely thermal degradation. As a consequence, the depolymerisation reaction via the six-membered ring transition state is limited in extent and diaminotoluene is not evolved. The absence of toluene diisocyanate is proposed to be a result of this species undergoing oxidative degradation reactions which lead to it being incorporated into the char.

KW - polyurethane foam

KW - TDI

KW - solid state NMR

KW - condensed phase

KW - thermal degradation

KW - oxidation

UR - https://www.sciencedirect.com/journal/polymer-degradation-and-stability

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DO - 10.1016/j.polymdegradstab.2018.12.027

M3 - Article

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SP - 57