Investigation and Comparison of Bagasse Soda Pulps Properties Bleached with Total Chlorine Free (TCF) and Elemental Chlorine Free (ECF) Stages

The objective of this research was accomplished on the effects of total chlorine free (TCF) and elemental chlorine free (ECF) bleaching on optical and mechanical properties of bagasse soda pulps. For this purpose, some unbleached bagasse soda pulps were randomly selected from Ahvaz Pars industry. Then these pulps were bleached with one, two and three P, OP, OPY, O(Ep)P, EHP and O(Ep)H bleaching stages by using oxygen(O) hydrogen peroxide(P), alkali extraction with hydrogen peroxide(Ep), sodium hypochlorite(H) and sodium dithionite(Y). The hand sheets with 70 gr/m2 were prepared from above-mentioned of pulps, and then the optical and mechanical properties were measured and compared according by using TAPPI standard test methods. The results showed that brightness, greenness, tear (except EHP stages), tensile, burst, breaking length strengths and folds were increased and opacity and a* factor were decreased by ECF and TCF bleaching stages. The effects of TCF bleaching stages were more sensible than ECF bleaching stages in improve of bagasse soda properties, too. In general, role of three OPY and O(Ep)H stages and two OP bleaching stages were better than EH(control) stage and unbleached bagasse soda pulps mill in improve of brightness and its paper strengths, too.