This study has shown that ultrafiltration allows the selective extraction from industrial black liquors of lignin fraction with specific thermo-mechanical properties, which can be matched to the intended end uses. Ultrafiltration resulted in the efficient fractionation of kraft lignin according to its molecular weight, with an accumulation of sulfur-containing compounds in the low-molecular weight fractions. The obtained lignin samples had a varying quantities of functional groups, which correlated with their molecular weight with decreased molecular size, the lignin fractions had a higher amount of phenolic hydroxyl groups and fewer aliphatic hydroxyl groups. Depending on the molecular weight, glass-transition temperatures (Tg) between 70 and 170C were obtained for lignin samples isolated from the same batch of black liquor, a tendency confirmed by two independent methods, DSC, and dynamic rheology (DMA). The Fox-Flory equation adequately described the relationship between the number average molecular masses (Mn) and T g's-irrespective of the method applied. DMA showed that low-molecular-weight lignin exhibits a good flow behavior as well as high-temperature crosslinking capability. Unfractionated and high molecular weight lignin (Mw >5 kDa), on the other hand, do not soften sufficiently and may require additional modifications for use in thermal processings where melt-flow is required as the first step.

Sevastyanova, O., Helander, M., Chowdhury, S., Lange, H., Wedin, H., Ek, M., et al. (2014). Tailoring the Molecular and Thermo-Mechanical Properties of Kraft Lignin by Ultra-Filtration. JOURNAL OF APPLIED POLYMER SCIENCE, 131(18), n/a-n/a [10.1002/app.40799].

Tailoring the Molecular and Thermo-Mechanical Properties of Kraft Lignin by Ultra-Filtration

LANGE Heiko;
2014

Abstract

This study has shown that ultrafiltration allows the selective extraction from industrial black liquors of lignin fraction with specific thermo-mechanical properties, which can be matched to the intended end uses. Ultrafiltration resulted in the efficient fractionation of kraft lignin according to its molecular weight, with an accumulation of sulfur-containing compounds in the low-molecular weight fractions. The obtained lignin samples had a varying quantities of functional groups, which correlated with their molecular weight with decreased molecular size, the lignin fractions had a higher amount of phenolic hydroxyl groups and fewer aliphatic hydroxyl groups. Depending on the molecular weight, glass-transition temperatures (Tg) between 70 and 170C were obtained for lignin samples isolated from the same batch of black liquor, a tendency confirmed by two independent methods, DSC, and dynamic rheology (DMA). The Fox-Flory equation adequately described the relationship between the number average molecular masses (Mn) and T g's-irrespective of the method applied. DMA showed that low-molecular-weight lignin exhibits a good flow behavior as well as high-temperature crosslinking capability. Unfractionated and high molecular weight lignin (Mw >5 kDa), on the other hand, do not soften sufficiently and may require additional modifications for use in thermal processings where melt-flow is required as the first step.
Articolo in rivista - Articolo scientifico
Biopolymers and renewable polymers; glass transition; rheology; crosslinking; thermal properties.
English
2014
131
18
n/a
n/a
reserved
Sevastyanova, O., Helander, M., Chowdhury, S., Lange, H., Wedin, H., Ek, M., et al. (2014). Tailoring the Molecular and Thermo-Mechanical Properties of Kraft Lignin by Ultra-Filtration. JOURNAL OF APPLIED POLYMER SCIENCE, 131(18), n/a-n/a [10.1002/app.40799].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/316842
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