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|Type:||Artigo de periódico|
|Title:||Evaluation Of Bleachability And Brightness Stability Of Thermomechanical Pulp From Eucalyptus Grandis [avaliação Da Branqueabilidade E Da Estabilidade De Alvura De Uma Polpa Termomeĉnica De Eucalyptus Grandis]|
|Abstract:||The bleachability and brightness stability of a thermomechanical pulp (TMP) produced from Eucalyptus grandis wood chips were evaluated. Unbleached TMP (freeness of 480 mL and 60% ISO brightness) was bleached with a QP sequence (treatment with DTPA followed by alkaline hydrogen peroxide bleaching). During the peroxide stage, the bleachability of the TMP from E. grandis was evaluated according to a 2 4 experimental design. The variables appraised were peroxide charge, consistency, temperature and bleaching time. The maximum final brightness in a single peroxide stage was reached with 8% of hydrogen peroxide, 10% of consistency, 30 minutes of bleaching and 60°C. Increased peroxide levels had negligible effects on the final brightness, whilst consistency levels higher than 10% reduced the TMP brightness up to 15 points. High-brightness pulps rapidly reverted by exposing the bleached TMP to light or heat.|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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