Studies on Mechanical Strength of Paper

Abstract

Effects of fiber length on mechanical strength, chemical strength, chemical properties and hygroscopic characteristics were investigated. Mechanical strength especially was measured inthe normal condition (R.H. 65%) and dry condition. The dry condition was obtained by the folloNN ing ways ; the paper sample was dried at 105°C for 3hr, and was impregnated with water-free oil.1) Tensile strength for fraction pulp decreases with increasing average fiber length, and in case of the same average fiber length, the tensile strength for whole pulp is higher than that for fraction pulp.2) Folding endurance and tearing resistance for fraction pulp increase with increasing average fiber length. There is a straight-line relationship between the average fiber length and tearing resistance of paper.3) Pentosan content of pulp decreases with increasing average fiber length, but DP of pulp increases.4) Moisture regain, dimensional change, water of monolayer absorption and internal surface area of paper decrease with increasing average fiber length, but crystallinites of paper fiber increase.