Shear modulus of single wood pulp fibers from torsion tests

Abstract The shear modulus of pulp fibers is difficult to measure and only very little literature available on this topic. In work we are introducing a method fiber property utilizing custom built instrument. From the geometry cross section, twisting angle applied torque, derived by de Saint Venant’s theory torsion. deformation moving coil mechanism. support rotating part consists taut bands, making it nearly frictionless, which allows easy control torque twist fiber. A permanent magnet meter was fitted with sample holder for references. Measurements fine metal bands were performed validate irregular shape reconstructed from several microtome cuts an apparent torsion constant computed applying theory. Fibers two types industrial measured: thermomechanical (TMP) Kraft pulp. average determined as (2.13 $${\pm }$$ ± 0.36) GPa TMP (2.51 0.50) fibers, respectively. showed smaller but, due their less collapsed state, higher torsional rigidity than kraft fibers.