The potential of using tomato stalk pulp as long fibers in reinforcement of wheat straw commercial cold soda pulp

In this research, the strengthening of wheat straw cold soda pulp produced in Iran using tomato stalk fibers prepared by soda-anthraquinone process was investigated. Length, diameter, cell cavity diameter, and fiber thickness; Runkle ratio, slenderness ratio and flexibility coefficient of tomato stalk fibers were measured. The chemical composition of tomato stalk including percentage of ash, lignin, cellulose and hemicelluloses were determined. Unbleached pulp was produced from tomato stalk in 180 minutes with optimal conditions of 170°C, 20% active alkali and 0.1% anthraquinone. The average yield percentage after screening and kappa number of tomato stalk pulp were measured as 43.09 % and 27.33, respectively. Hand sheets made from this pulp has the tensile index of 34.75 (Nm/g), tear index of 6.02 (mNm2/g) and burst index of 2.16 (kPam2/g), respectively. The combination of tomato stalk pulp with wheat straw cold soda pulp available in the market was done at three levels: 75:25, 50:50 and 25:75. The amount of tensile, tear and burst indices increased by 28, 63 and 36 % respectively after mixing. The most obvious effect of mixing in terms of mechanical properties is observed in the increase of tear index. The results show that the addition of unbleached soda-anthraquinone tomato stalk pulp as an unused agricultural waste to the unbleached wheat straw cold soda pulp can improve and increase the mechanical indices by reducing the weaknesses of the cold soda pulp and also leads to expanding the application and demand for this pulp.