Abstract
In order to understand the physical properties of paper, it is important to study the porous structure and the state of pores in paper. This work was undertaken to investigate the relationships between the physical properties and porous structure of paper (handsheets (100g/m2) made from N- and L-BKP were used). The porosity of paper was determine by the mercury pressure porosimeter.
The following results were obtained.
(1) Pore size was influenced by beating degree. In the early time of beating, large pores more than 3 μm decreased rapidly, and then the decreasing rate of all pore radius became small.
(2) The effect of calendar treatment of paper showed same tendency as increasing of beating degree.
(3) The pore radius about 1 to 10 μm found in paper were correspond to the order of size of air spaces or voids among fibers and uneven structure of paper surface. The micro-pores of about 0.1 μm found in paper, were correspond to space of inter fibril structure or lumen of fiber.
(4) The author found the correlation between cumulative pore volume distribution curve and physical properties of paper. The upper limit pore radius (M50 μm) occupying 50 vol. % of pore volume calculated from cumulative pore volume distribution curve showed the existence of following correlation to physical properties of paper.
M50∝ 1/tensil strength
M50∝ 1/bulk density
M50∝ water absorption degree
M50∝ -log (air permeability)
log M50∝ -log (beating degree)
