Abstract: Pulping properties of Eucalyptus urograndis×E.grandis (E.u.×E.g.) and Acacia mangium Willd. wood chips were investigated by using preconditioning refinerchemical alkaline peroxide mechanical pulping(P-RC APMP) process. Specific refining energies were recorded and both physical properties and optical properties of pulps were evaluated. Results show that similar brightness of P-RC APMP pulps could be produced from both E.u.×E.g. and A.mangium wood chips. At the chemical dosage level of H₂O₂ 4.0% and NaOH 3.5%, which is a very low chemical consumption, pulp brightness of both pulps was able to reach 75%ISO. The pulp yield of A. mangium wood chips was 3.0% higher than that of E.u.×E.g. wood chip. At the freeness level of 250mL Canadian Standard Freeness (CSF), pulps from A.mangium wood chips was much stronger than that from E.u.×E.g.. For example, the tensile strength of P-RC APMP pulp from A.mangium was above 26N·m/g, about 30% higher than that of E.u.×E.g. pulp; Further refining could improve chemimechanical pulp strength. For the same CSF level,pulping of A.mangium wood chips requires more refining energy than that of E.u.×E.g. wood chips.

Key words: Eucalyptus urograndis×E.grandis, Acacia mangium Willd., P-RC APMP