Influence of Fiber Composition and Drying Conditions on the Bending Stiffness of Paper

Abstract

Changes in thickness, elastic modulus, and bending stiffness were studied for handsheets prepared using different fiber compositions and dried under restraint or unrestraint conditions, when exposed to various humidity conditions. Four sets of experimental studies were carried out to investigate the effect of (1) different amounts of fines (or long fibers), (2) two-ply sheet forming, (3) high temperature restraint press drying, and (4) the use of recycled fibers on the thickness, elastic modulus, and bending stiffness. The results showed that thickness, elastic modulus, and bending stiffness changed depending upon the fiber composition, single or multi-ply forming, drying conditions, and recycling of fibers. Thickness change, restraint drying, and fiber hornification during recycling were the principal factors affecting the bending stiffness in cyclic humidity conditions.