TY - JOUR
T1 - Impact of residual extractives on the thermal stability of softwood Kraft pulp
AU - Jusner, Paul
AU - Barbini, Stefano
AU - Schiehser, Sonja
AU - Bacher, Markus
AU - Schwaiger, Elisabeth
AU - Potthast, Antje
AU - Rosenau, Thomas
N1 - Funding Information:
The financial support by the Austrian Biorefinery Center Tulln (ABCT) is gratefully acknowledged.
Publisher Copyright:
© 2022, The Author(s).
PY - 2022/11
Y1 - 2022/11
N2 - Wood extractives are known to cause problems during the production of pulp and paper and to impact their mechanical properties. In the present work, we systematically explored whether minute residual amounts of extractives that reprecipitate on the fiber surface in the final stages of the pulping process would lower the thermal resilience of softwood Kraft pulp. Pulp samples subjected to different extraction methods were characterized by means of thermogravimetric analysis. The compound classes constituting the respective extracts were identified and quantified via gas chromatography-mass spectrometry/flame ionization detector (GC-MS/FID) and the influence of the individual compound classes on the thermal stability of the samples was investigated separately. Soxhlet extraction with an ethanol/toluene solvent system clearly led to increased thermal stability. Besides fatty acids and resin acids also sterols and sterol esters that do not carry carboxylic acid functionalities contributed to the deterioration of the thermal pulp properties. Lateral order indices derived from Fourier transformed infrared spectra and crystallinity indices derived from solid-state 13C nuclear magnetic resonance spectra indicate that upon thermal degradation, the presence of even minute amounts of extractives leads to an increased degree of supramolecular disorder. Moreover, the characterization of the samples’ carbohydrate composition by means of acidic hydrolysis showed a tendency towards facilitated pyrolysis of the hemicelluloses if extractives were present in the pulp.
AB - Wood extractives are known to cause problems during the production of pulp and paper and to impact their mechanical properties. In the present work, we systematically explored whether minute residual amounts of extractives that reprecipitate on the fiber surface in the final stages of the pulping process would lower the thermal resilience of softwood Kraft pulp. Pulp samples subjected to different extraction methods were characterized by means of thermogravimetric analysis. The compound classes constituting the respective extracts were identified and quantified via gas chromatography-mass spectrometry/flame ionization detector (GC-MS/FID) and the influence of the individual compound classes on the thermal stability of the samples was investigated separately. Soxhlet extraction with an ethanol/toluene solvent system clearly led to increased thermal stability. Besides fatty acids and resin acids also sterols and sterol esters that do not carry carboxylic acid functionalities contributed to the deterioration of the thermal pulp properties. Lateral order indices derived from Fourier transformed infrared spectra and crystallinity indices derived from solid-state 13C nuclear magnetic resonance spectra indicate that upon thermal degradation, the presence of even minute amounts of extractives leads to an increased degree of supramolecular disorder. Moreover, the characterization of the samples’ carbohydrate composition by means of acidic hydrolysis showed a tendency towards facilitated pyrolysis of the hemicelluloses if extractives were present in the pulp.
KW - Carbohydrate composition
KW - Extractives
KW - Softwood Kraft pulp
KW - Supramolecular order
KW - Thermal stability
KW - Thermogravimetric analysis (TGA)
UR - http://www.scopus.com/inward/record.url?scp=85136795209&partnerID=8YFLogxK
U2 - 10.1007/s10570-022-04807-z
DO - 10.1007/s10570-022-04807-z
M3 - Article
AN - SCOPUS:85136795209
SN - 0969-0239
VL - 29
SP - 8797
EP - 8810
JO - Cellulose
JF - Cellulose
IS - 16
ER -