Extracting hemicelluloses prior to aspen chemi-thermomechanical pulping: Effects of pre-extraction on pulp properties

► The effects of acid pre-extraction on aspen chemi-thermomechanical pulp properties were investigated. ► Some hemicelluloses and acetic acid can be pre-extracted prior to CTMP pulping with sulfuric acid. ► Acid pre-extraction significantly reduced refining energy consumption to a given freeness. ► The resultant chips can still be used to produce mechanical pulps under suitable conditions. ► At similar specific refining energy, pulps with pre-extraction had higher strength, less shives, and more fines.