Effect of kenaf bast and whole stalk pulp use in combination with recycled packaging pulp on produced paper properties

In this study, the effect of soda and kraft pulp of kenaf bast and whole stalk (Cubana cultivar from Hibiscus cannabinus) application on the possibility of improving in recycled packaging paper was investigated. Kenaf bast and whole stalk pulping was conducted by both soda and kraft processes. Pulping conditions included of liquor to kenaf chips ratio of 8:1, cooking temperature of 165 °C, active alkali of 28%, sulfidity of 25% and different cooking time to achieve the target kappa number of 25. Results showed that cooking time in the bast pulping was much lower than that in the whole stalk (25 and 35 in kraft and soda processes, respectively). However, the cooking times in the whole stalk pulping, to achieve the kappa number of 25, were 120 and 180 in kraft and soda processes, respectively. Because the bast to core ratio was 40-60, the combination of kenaf Pulps was conducted about 20% with the constant content of kenaf bast fiber. The findings indicated that kenaf bast pulps had the most strength properties in both of soda and kraft processes, but strength properties of soda whole stalk pulp were lower than kraft whole stalk pulp. In these pulp mixtures, the mixture of kraft pulp of kenaf whole stalk with recycled pulp had the most strength properties.