Iconic Papers from The Pulp and Paper Fundamental Research Symposia

Steve I'Anson: To start off our new venture of including reproductions of some iconic papers from the symposia, I would like to recommend the following paper by Petri Mäkelä which is included in the proceedings of the 2009 symposium held at St Anne's College, Oxford and which was awarded the Van den Akker Prize for Paper Physics.
This paper takes a somewhat contentious proposal on the link between drying strain and tensile stiffness and tests it with a set of elegantly designed experiments, showing that it is entirely justified. In Petri's abstract he states:

"The results showed that the tensile stiffness, tensile strength, strain at break, and tensile energy absorption of the dried sheets, respectively, were linearly related to the total strain during drying of the sheets. These linear relations were shown to be unaffected by drying temperature, final drying time, and drying constraint history. On the other hand, the corresponding relations between the in-plane tensile properties and final drying stress were found to be both non-linear and greatly dependent on the drying constraint history."

P. Mäkelä. Effect of drying conditions on the tensile properties of paper. In Advances in Pulp and Paper Science Research, Oxford 2009, Trans. XIVth Fund. Res. Symp. Oxford, 2009, (S. J. I'Anson, ed.), pp 1079–1094, FRC, Manchester, 2009. ISBN: 978-0-9545272-6-6.

Warren Batchelor: This very well written review, thoroughly covering both historical and contemporary literature, is the Fundamental Research Symposium paper that I most frequently recommend to group members and colleagues as essential reading. Lindström, Wågberg and Larsson produced this paper as a review of the subject and the 105 pages, including 21pages of references to the literature, achieve this goal admirably.

T. Lindström, L. Wågberg and T. Larsson. On the nature of joint strength in paper - a review of dry and wet strength resins used in paper manufacturing. In Advances in Paper Science and Technology, Trans. XIIIth Fund. Res. Symp. Cambridge, 2005, (S. J. I'Anson, ed.), pp 457–562, FRC, Manchester, 2005. ISBN: 0 9545272 3 2.

Bill Sampson: This paper represents the first attempt to apply the statistical geometry of fibre networks to model the structure of paper. The emphasis is on thin random, i.e. Poissonian, fibre networks which have become the standard reference model for the structure of paper; several key results are presented for these, for example: the expected number of crossings per fibre, the expected free fibre length and its distribution and an estimate of the mean polygon (pore) area. These results have guided subsequent analyses in the study of paper structure for over 50 years; they have been applied to the study of non-woven textiles also and have more recently been applied in emerging fields such as the characterization of electrospun polymer networks and nanotube assemblies, though these works typically cite a separate, and arguably less polished, version of the theory published a year beforehand in Tappi Journal. Importantly the article considers also the effects of anisotropy and flocculation on structural parameters and presents a first attempt at modelling multiplanar structures. This is a seminal work of significant breadth and represents an excellent example of the application of original and fundamental science to our understanding of paper properties.

H. Corte and O.J. Kallmes. Statistical geometry of a fibrous network. In Formation and Structure of Paper, Trans. IInd Fund. Res. Symp. Oxford, 1961, (F. Bolam, ed.), pp13–46, FRC, Manchester, 2003. ISBN: 0 9541126 2 8

Norayr Gurnagul: Derek Page and his co-workers developed numerous image analysis procedures to quantify fibre deformations such as curl and were among the first group of researchers to link these measurements to observed pulp and paper properties. During that time curl and microcompression were often disregarded because they could not be easily measured. This paper gives an excellent review of the importance of curl and microcompression for mechanical and chemical pulps. Since this seminal publication, numerous developments have led to the manufacture of both laboratory and online equipment to measure fibre curl, kink and other parameters.

D.H. Page, R.S. Seth, B.D. Jordan and M.C. Barbe. Curls, crimps, kinks and microcompressions in pulp fibres – their origin, measurement and significance. In Papermaking Raw Materials, Trans. VIIIth Fund. Res. Symp. Oxford, 1985, (V. Punton, ed.), pp 183–227, FRC, Manchester, 2003. ISBN: 0 9541126 8 7.

Doug Coffin: To me, this contribution by Seth and Page stands out as one of the significant contributions in paper mechanics providing us a frame of reference from which we can evaluate the mechanical response of paper and how we can change it with processing. The concept that one efficiency factor can be used to explain the contribution from changes in degree of bonding on the resultant stress-strain curve is profound. It means that the basic shape of the stress-strain curve is a reflection of the fibers and its constituent materials. Even after multiple readings, I am still picking out useful information from this manuscript. One can extrapolate much from the work. For example, useful refining energy only allows us to better connect our materials together and better utilize the material to carry load (higher efficiency factor). Excessive refining energy damages fibers thus permanently changing the shape of the stress-strain curve. The inverse of the efficiency factor can be considered a load magnification factor, and thus easily incorporated into a constitutive equation to account for the role of bonding on creep. Damage evolution can be tracked with changes in the efficiency factor. For me, the use of the efficiency factor provides a simple and effective means of separating the role of bonding and fibers. The use of the efficiency factor provides a strong basis from which one can evaluate and interpret their results. I think it could be utilized to a greater extent than current practice shows, and by framing work in this vein one could further elucidate secondary and tertiary contributions of fibers and bonds to the mechanical behavior of paper.

R.S. Seth and D.H. Page. The stress-strain curve of paper, In The Role of Fundamental Research in Paper Making, Trans. VIIth Fund. Res. Symp. Cambridge 1981, (J. Brander, ed.), pp 421–452, FRC Manchester, 2003. ISBN: 0 9541126 7 9

The proceedings of the first 15 FRC Symposia are on fully searchable CDs. Ordering information is available on the FRC homepage: www.ppfrs.org Delegates to the recent 16th Symposium in Oxford in September 2017 received a fully searchable copy of ALL past proceedings on a Flash Drive.