Literature

"A Note on the Mechanism of Tearing Strength," by Derek Page. Tappi Journal Mar. 1944 p. 201-203. High tearing strength appears to depend mainly on fiber strength, rather than on fiber bonding. (3A9.7)

Prüfung von Papier, Pappe, Zellstoff und Holzstoff. 3 vols. Hrsg. von Werner Franke. The second and third volumes of this set of books on test methods for paper, board, cellulose and wood is favorably reviewed by Gerd Brinkhus in Restauro, 1/94 (Jan.-Feb.), p. 15. The first volume appeared in 1991 or 1992 and was reviewed earlier, so he does not say much about it. The second volume covers microscopic and photometric (?) methods, while the third covers physical tests for pulp. Both were published in 1993. The full references for them are:

Bd. 2: Werner Franke (Hrsg.) Mikroskopische und photometrische Verfahren. Berlin u.a.: Springer 1993. XVII, 431 S., 202 Abb., DM 298

Bd. 3: Otmar Töppel: Physikalisch-technologische prüfung der Papierfaserstoffe. Berlin u.a.: Springer 1993. XV, 252 S., 110 Abb., DM 198. (3B1)

"Physical Aging in Paper: A Newly Recognised Effect," by Z.V. Padanyi. Paper presented at 47th Appita Annual General Conference held 19-23 Apr. 1993 at Rotarua, New Zealand. Vol. 2, pp 639-640 (Parkville, Australia: Appita, 1993, 818 pp, 2 vols. 1993 PBA Abstr. # 4864 )

The author defines physical aging of paper as "structural changes taking place at the molecular level and involving no chemical changes." Four tests carried out on linerboard led the author to conclude that elastic and viscous responses of paper may be influenced by physical aging as evidenced by the rapid failure of corrugated boxes under variable humidity conditions.

A subsequent paper on this topic by Padanyi, given at the FRC 10th Fundamental Research Symposium in September, was reported in the November issue of this Newsletter.

Comment: Paper is known to deteriorate more rapidly under certain conditions than under others. Such conditions or stressors include elevated temperature and/or relative humidity, containment in a small enclosure, gamma radiation, light at different wave lengths, and cycling of temperature and humidity. All have been used to induce accelerated aging. Deterioration resulting from all these physical conditions takes place largely through induced chemical changes within the paper and between it and its surroundings. The effects induced in a given material may vary according to the stressor used. Both the chemical and the physical properties of the paper change measurably as a result. If anyone wants to show that a type of physical deterioration has been induced that does not involve any chemical deterioration (i.e., "physical aging"), then they have to demonstrate that no chemical changes have taken place. This task would be expensive and time-consuming, and perhaps even impossible. (3B1.2)