Effects of Mountain Pine Beetle Grey-Stage Infestation and Chip Moisture Content on TMP Pulping of Lodgepole Pine

Abstract

We performed pilot-plant thermomechanical pulping on green and dry, mountain pine beetle-infested, grey-stage lodgepole pine sapwood chips with different moisture contents. The energy requirements and the tensile strength of the thermomechanical pulps (TMPs) from the dry, early-grey-stage chips were similar to those from the green chips, but there were indications of slightly higher energy requirements and lower tensile strength for the pulps from the late-grey-stage chips. The late- or early-grey-stage TMP had lower sheet density (because of the lower chip moisture content), lower ISO brightness, and higher handsheet surface roughness than the green TMP. Chip blends with 50% and 25% of late-grey-stage chips could be used to produce TMP pulps with energy require-ment, tensile strength, handsheet surface roughness, and density similar to those of green TMP, but with lower ISO brightness. The fiber saturation points of the green and the late-grey-stage chips were estimated to be 23.1% and 22.4% (wet basis), respectively.