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Pretreatmentof biomass is expected to improve the pulp propertiesand facilitate the main components in the raw materials to be betterused. In this work, the refining energy consumption and propertiesof the poplar chemithermomechanical pulp (CTMP) from different autohydrolysispretreatment intensities of wood chips were investigated, and thepulp bleaching ability was also studied. The results showed that theCTMP with autohydrolysis pretreatment at a severity factor of 3.47could have a 26% energy reduction in pressurized refining, a 60% energysaving in PFI refining, and 44% and 46% increases in tensile and tearindices, respectively. Autohydrolysis pretreatment prior to pulpingcould result in CTMP with a higher water retention value, higher finescontent, better strength properties, lower shives content, and lowerbulk and ISO brightness after PFI refining. The brightness of CTMPcan be improved by alkaline peroxide bleaching. [ABSTRACT FROM AUTHOR]

Pre-extraction of hemicelluloses prior to pulping andconversionof the extracted hemicelluloses to other byproducts will provide additionalrevenue to the traditional pulp and paper industry. The effect ofhemicelluloses pre-extraction with dilute sulfuric acid on the propertiesand bleachability of aspen (Populus tremuloides)chemithermomechanical pulp (CTMP) was investigated. The acid pre-extractionsignificantly reduced refining energy consumption to a given freeness.However, at the same freeness, the acid pre-extraction resulted inthe reduction of bulk, tensile index, and zero-span breaking length,fewer long fibers and more fines, but an increase of the Scott bondstrength.Alkaline peroxide bleaching can compensate the strength loss, butthe bleachability of pulps with acid pre-extraction was lower thanthat of the control. [ABSTRACT FROM AUTHOR]