Evaluating pulp stiffness from fibre bundles by ultrasound

T. Karppinen, R. Montonen, Marjo Määttänen, A. Ekman, M. Myllys, J. Timonen, Edward Haegström

Research output: Contribution to journalArticleScientificpeer-review

1 Citation (Scopus)

Abstract

A non-destructive ultrasonic tester was developed to measure the stiffness of pulp bundles. The mechanical properties of pulp are important when estimating the behaviour of paper under stress. Currently available pulp tests are tedious and alter the fibres structurally and mechanically. The developed tester employs (933 ± 15) kHz tweezer-like ultrasonic transducers and time-of-flight measurement through (9.0 ± 2.5) mm long and (0.8 ± 0.1) mm thick fibre bundles kept at (19.1 ± 0.4) °C and (62 ± 1)% RH. We determined the stiffness of soft wood pulps produced by three kraft pulping modifications: standard kraft pulp, (5.2 ± 0.4) GPa, prehydrolysis kraft pulp, (4.3 ± 0.4) GPa, and alkali extracted prehydrolysis kraft pulp, (3.3 ± 0.4) GPa. Prehydrolysis and alkali extraction processes mainly lowered the hemicellulose content of the pulps, which essentially decreased the fibre-wall stiffness hence impairing the stiffness of the fibre networks. Our results indicate that the method allows ranking of pulps according to their stiffness determined from bundle-like samples taken at an early phase of the papermaking process.
Original languageEnglish
Article number065603
JournalMeasurement Science and Technology
Volume23
Issue number6
DOIs
Publication statusPublished - 2012
MoE publication typeA1 Journal article-refereed

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Fiber Bundle
Ultrasound
bundles
Pulp
stiffness
Stiffness
Ultrasonics
fibers
Fibers
Kraft pulp
Fiber
test equipment
alkalies
Bundle
ultrasonics
ranking
Time-of-flight
Kraft process
Ultrasonic transducers
Transducer

Cite this

Karppinen, T., Montonen, R., Määttänen, M., Ekman, A., Myllys, M., Timonen, J., & Haegström, E. (2012). Evaluating pulp stiffness from fibre bundles by ultrasound. Measurement Science and Technology, 23(6), [065603]. https://doi.org/10.1088/0957-0233/23/6/065603
Karppinen, T. ; Montonen, R. ; Määttänen, Marjo ; Ekman, A. ; Myllys, M. ; Timonen, J. ; Haegström, Edward. / Evaluating pulp stiffness from fibre bundles by ultrasound. In: Measurement Science and Technology. 2012 ; Vol. 23, No. 6.
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Karppinen, T, Montonen, R, Määttänen, M, Ekman, A, Myllys, M, Timonen, J & Haegström, E 2012, 'Evaluating pulp stiffness from fibre bundles by ultrasound', Measurement Science and Technology, vol. 23, no. 6, 065603. https://doi.org/10.1088/0957-0233/23/6/065603

Evaluating pulp stiffness from fibre bundles by ultrasound. / Karppinen, T.; Montonen, R.; Määttänen, Marjo; Ekman, A.; Myllys, M.; Timonen, J.; Haegström, Edward.

In: Measurement Science and Technology, Vol. 23, No. 6, 065603, 2012.

Research output: Contribution to journalArticleScientificpeer-review

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AU - Karppinen, T.

AU - Montonen, R.

AU - Määttänen, Marjo

AU - Ekman, A.

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AU - Haegström, Edward

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AB - A non-destructive ultrasonic tester was developed to measure the stiffness of pulp bundles. The mechanical properties of pulp are important when estimating the behaviour of paper under stress. Currently available pulp tests are tedious and alter the fibres structurally and mechanically. The developed tester employs (933 ± 15) kHz tweezer-like ultrasonic transducers and time-of-flight measurement through (9.0 ± 2.5) mm long and (0.8 ± 0.1) mm thick fibre bundles kept at (19.1 ± 0.4) °C and (62 ± 1)% RH. We determined the stiffness of soft wood pulps produced by three kraft pulping modifications: standard kraft pulp, (5.2 ± 0.4) GPa, prehydrolysis kraft pulp, (4.3 ± 0.4) GPa, and alkali extracted prehydrolysis kraft pulp, (3.3 ± 0.4) GPa. Prehydrolysis and alkali extraction processes mainly lowered the hemicellulose content of the pulps, which essentially decreased the fibre-wall stiffness hence impairing the stiffness of the fibre networks. Our results indicate that the method allows ranking of pulps according to their stiffness determined from bundle-like samples taken at an early phase of the papermaking process.

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