TENSILE-STRENGTH OF A MIXTURE OF 2 PULPS

A theory on the effect of distributions of pulp fibre properties on th e tensile strength of paper is applied to a furnish consisting of two pulps. The tensile strength of a mixture of two pulps of different duc tility may be lower than would be expected assuming linear mass-propor tion additivity of the tensile indices of the components. This phenome non is most pronounced in cases where the stronger of the pulps has a lower modulus, i.e. a lower ratio of strength and rupture strain. The tensile strength of a mixture of two pulps can be interpreted as the p roduct of the mean specific modulus and the rupture strain of the mixt ure. The specific moduli of the constituent pulps appear to remain con stant with changing sheet composition, brit the rupture strain of the mixture depends on particle size and conformability distributions, whi ch themselves change with the proportions of the pulp components.