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V. C. Setterholm. Factors that affect the stiffness of paper. In The Fundamental Properties of Paper Related to its Uses, Trans. of the Vth Fund. Res. Symp. Cambridge, 1973, (F. Bolam, ed.), pp 253–266, FRC, Manchester, 2018.


Use of paper for structural purposes has prompted research toward better utilisation of materials, determining potential stiffness and procedures to attain such stiffness.

Stiffness is dependent on thickness and a new definition of thickness is proposed that facilitates the quantification of paper stiffness with traditional engineering concepts without introducing errors caused by surface roughness.

Perhaps equally important as thickness in achieving potential stiffness is specific gravity, because the modulus of elasticity will usually vary as the cube of specific gravity if densification occurs while paper is wet.

The most efficient means for control of stiffness is restraint during drying, with a potential for threefold increases in modulus of elasticity. Even larger increases in stiffness in the order of five or sevenfold are awaiting a better means of controlling fibre orientation.

A new method is being developed for quantifying interfibre bonding that will be independent of sheet grammage and additives.

Moisture is seen as the greatest obstacle to making high performance structural fibre products because of the inability of these products to maintain reasonable levels of stiffness when wet, even when treated with synthetic resins. In spite of this problem, the potential high stiffness and strength-to-weight ratios that are available in wood fibre makes the creation of new structural products from pulp fibres inevitable.

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