The effect of kenaf core and bast mixing on soda pulping and paper strengths

Paper industry has been experiencing growing shortage of cellulosic material over the last decades. As a fast-growing plant, kenaf has good potential to compensate wood shortages taking into account its long historical record of cultivation in Iran. Kenaf variety of 432 was collected from Varamin research station. Kenaf stalk yield was determined roughly as 10.5 air-dried metric tonnes (ADMT) per hectare for a single crop rotation. Soda pulping of core, bast and their mixture were carried out at three weight percent ratios of 50:50, 40:60 and 30:70. H-factor for the delignification process was adjusted about 800 using cooking treatment combination of 175 °C, 30 min, 18% sodium hydroxide, and 5:1 liquor to raw material ratio. Under similar cooking condition, yield and kappa no. of soda pulp prepared from the mixture of kenaf core and bast showed highest yield and kappa number. Kappa no. decreased with increasing bast fiber percent from 50% to 70%, and required increased PFI revolution to achieve certain freeness. Handsheet properties including thickness, breaking length, burst and specially tear index increased at higher bast fiber content