Effect of beating time on properties of soda and monoethanolamine pulp from wheat straw

In this study, the effect of beating time on morphologic, physical and strength properties of soda and monoethanolamine pulps obtained from wheat straw was studied, in order to optimize the time for beating operation. Beating of the pulps was applied in different time by laboratory jokromill beater. The results showed that rising time of beating leads to increasing the freeness (SR) of pulps and monoethanolamine pulp reached to maximum amount of freeness (SR) in less time as compared to soda pulp. In addition, it is found that monoethanolamin pulp obtained the maximum amount of tensile index (91.3 N.m/g) after 30 min beating time and after that longer time of beating process had no significant effect on increasing the tensile index. About soda pulp it is observed that tensile index was increased significantly by rising the time of beating process and for this kind of pulp, maximum amount of tensile index (87.7N.m/g) was obtained in 50 min beating process. The highest burst index for soda pulp was 5 Kp.m2 which was obtained by 50 min beating process. About mono ethanolamine pulp burst index increased by rising time of beating Process and reached to its maximum amount (5.6 Kp.m2) and after that its amount decreased. Rising the time of beating process led to decreasing the tear index in both of kinds of pulp consist of monoethanolamin and soda pulp. The results showed that mono ethanolamine pulp had the higher yield and better beating ability in comparison with soda pulp which can be caused by better ability for carbohydrates and minerals retaining in monoethanolamin pulp.