Paper in a calender nip is subjected to a pressure pulse which reduces its thickness and roughness, thus improving the product quality. Strain recovery after the nip is time-dependent, and some permanent strain remains. The material behaviour is viscoelastic; recovery depends on the pulse magnitude and duration, and does not occur immediately on exiting the nip. An improved description of the viscoelastic response to a calender pulse would allow design of adaptive control systems using feedforward techniques. / Measurements of paper thickness in the nip, immediately after the nip and 24 hours after calendering were made with newsprint sheets running through an experimental calender operating at industrial conditions. The calculated strains were first related to the operating conditions using empirical curve-fitting methods, then using linear viscoelastic models. Empirical results describe the data well, and can be used to design improved control systems. Linear viscoelastic modeling was less successful since the material behaviour is not linear. Photomicrographs of sheet cross-sections were taken, and the observed non-linearities were discussed qualitatively in terms of paper and fibre properties.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.28698 |
| Date | January 1994 |
| Creators | Browne, Thomas, 1955- |
| Contributors | Douglas, W. J. M. (advisor), Crotogino, R. H. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Chemical Engineering.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001448047, proquestno: NN05681, Theses scanned by UMI/ProQuest. |
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