The response of whole-stalk kenaf and kenaf core to chemimechanical treatments

The first part of the research subjected whole-stalk kenaf to impregnation with alkaline hydrogen peroxide, followed by disk refining. The alkali and hydrogen peroxide dosages were varied. An allca-to-peroxide dosage ratio of 1:1 resulted in improved pulp brightness. After post-refiner bleaching with hydrogen peroxide, it was possible to produce pulp with optical and strength properties similar to and superior than those found in the literature.; The second part of the research subjected kenaf core to soaking in water and sodium hydroxide solutions. Soaking time, temperature, and alkali concentration were varied. After soaking, the liquid pickup, water retention value (WRV), and fiber swelling were measured. For soaking in water only, water retention and fiber swelling were related to yield loss. Increasing the soaking temperature increased the rate of all measured responses. For soaking in alkali WRV was related to yield loss. All soaking variables had a negative effect on yield, and a good model was established. Alkali concentration had a strong negative effect on fiber swelling, while temperature had a more moderate positive effect. A good model for swelling was established.; The third part of the research subjected kenaf core to soaking in alkaline solutions, followed by bench-scale primary defibration and secondary refining. Soaking time, temperature, and alkali concentration were varied. An increase in alkali concentration had a negative effect on screened yield after primary defibration and a positive effect on freeness after primary defibration. An increase in temperature had a mild negative effect on screened yield, fiber length, and fiber coarseness after primary defibration and a mild positive effect on tensile strength after secondary refining. None of the soaking variables had any effect on the freeness response of the pulps when subjected to secondary refining. Significant differences were found for tear strength values for various pulps, and some of the values were significantly higher than reported in the literature. However, it was not possible to relate the differences to any of the soaking variables or the measured responses of water retention and swelling.