Biopolyols obtained via microwave-assisted liquefaction of lignin: structure, rheological, physical and thermal properties
The present study examined the application of polyols obtained via microwave-assisted liquefaction of lignin in the production of rigid polyurethane foam. Lignin was liquefied in crude glycerol and 1,4-butanediol at different temperatures (130–170 °C), without a catalyst and using various biomass co...
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Veröffentlicht in: | Wood science and technology 2018-05, Vol.52 (3), p.599-617 |
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Sprache: | eng |
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Zusammenfassung: | The present study examined the application of polyols obtained via microwave-assisted liquefaction of lignin in the production of rigid polyurethane foam. Lignin was liquefied in crude glycerol and 1,4-butanediol at different temperatures (130–170 °C), without a catalyst and using various biomass concentrations (15 and 30 wt%). The physicochemical properties, process yield, and FTIR-based identification of the obtained polyols were investigated. Under optimal conditions, i.e., a 5-min microwave heating time and a reaction temperature of 150 °C, a polyol characterized by a suitable hydroxyl number of 670 mg KOH/g was obtained with a 93% process yield. Liquefied biopolyol was directly used for the production of rigid polyurethane foams with the addition of polymeric diphenylmethane diisocyanate at the [NCO/OH] ratio of 2:1. Mechanical properties of the obtained foams gradually improved with increasing content of biopolyol. The 5% weight loss temperature (
T
5
) for bio-based foams was higher, respectively 6 and 13 °C compared to the petrochemical foam. Replacement of petrochemical polyether with biopolyols showed the ability to obtain rigid polyurethane foams from lignin and crude glycerol.
Graphical Abstract |
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ISSN: | 0043-7719 1432-5225 |
DOI: | 10.1007/s00226-018-0991-4 |