عنوان مقاله [English]
Kenaf is one of the most successful industrial plants for cultivation in Iran due to its unique properties for papermaking. The present research was conducted in order to supply virgin fiber for corrugated board to compensate shortage of wood in Iran. Harvest age is one of the important technical-economic aspects, so sampling was done from Cuban type of kenaf at three harvest ages of 5, 6 and 7 months and biomass was determined at 7 months of age. Soda-anthraquinone (AQ) pulping trials of kenaf core was carried out by 18 combination using 14% and 16% alkali charges, 0.2% AQ, three cooking time (60, 90, and 120 min.), three cooking temperature (155, 165, and 175 °C) and 7:1 liquor to core ratio. Pulp freeness was increased to 33 °SR by PFI mill beater and 127 g/m2 handsheets were made from the selected pulps including three harvest ages, two alkali charges (14% and 16%), cooking time of 120 min. and cooking temperature of 165 °C. The results showed that the green and dry biomass of kenaf was 32 and 7.7 ton/ ha, respectively. Screen yield, kappa number, and reject contents of optimal cooking combinations were measured in range of 53.71% to 48.76%, 78.73 to 118.27, and 1.58% to 4.41%, respectively. These results indicated that kenaf harvest age of 5 months that cooked by 16% alkali (F4 treatment) is the optimal treatment. It was found a direct relationship between harvest age with increasing of kappa number and screen yield of pulp. The results of physical properties of hand sheet showed that there are significant differences among the means of all these properties. Handsheet properties made from the optimal treatment, including tensile index of 85.7 Nm/g, burst index of 3.8 kPam2/g, tear index of 4.7 mNm2/g, RCT index of 16.8 Nm/g and CMT index of 1.9 Nm2/g are superior compare to the national standard specification of floating paper.