Abstract

In this study, chemical composition and morphological properties of cotton stalks growing in Turkey were investigated. Typical chemical properties determined were the amount of holocellulose, α-cellulose, cellulose, lignin, ash, silica, solubility of cold and hot water and 1% soda and alcohol–benzene. The holocellulose, α-cellulose, cellulose, lignin contents and solubility of cold and hot water and 1% soda and alcohol–benzene in cotton stalks were determined similar to those of some common non-wood and hardwood raw materials. Also, sodium borohydride (NaBH₄) modified kraft pulping was performed by using cotton stalks and the effects of NaBH₄ addition on the total pulp yield and chemical properties of pulps were investigated. In order to determine the optimum cooking parameters, 30 different laboratory experiments were performed. It was noted that the increasing level of NaBH₄ improved the screened pulp yield, pulp viscosity and degree of polymerization, reduced the kappa number. Consequently, total pulp yield was increased (15.66%) by NaBH₄ addition. Pulp viscosity and degree of polymerization were found to be higher than those of kraft one by about 1.60 and 1.73%, respectively. However, kappa number of NaBH₄ added to kraft pulp is lower (15.86%) than those of kraft one.

Key words: Cotton stalks, chemical composition, fiber properties, NaBH₄, pulp.