METHOD FOR INCREASING THE TENSILE STRENGTH OF PULP

A method for increasing the initial tensile strength of pulp, wherein the pulp is chemical pulp and provided as a suspension, is disclosed. The method comprises at least one of:a) adding a carboxyl derivative of cellulose to the pulp suspension in alkaline conditions, wherein the carboxyl derivative of cellulose has a degree of substitution (DS) of greater than 0.5; b) adding a carboxyl derivative of cellulose to the pulp suspension such that the fiber charge of the pulp reaches a predetermined value; c) pre-refining the pulp in the suspension, wherein the pre- refining is performed prior to drying the pulp; ord) wet calendering the pulp suspension, thereby at least partially straightening fibers of the pulp prior to dewatering and/or drying of the pulp; thereby obtaining modified pulp; and drying the modified pulp, thereby obtaining modified market pulp. The methodmayfurther comprise adding multivalent counterions to the pulp suspension, for example Mg2+, Ca2+, Al3+ or any combinations or mixtures thereof.