In this study, mountain pine beetle (MPB, Dendroctonus ponderosae Hopkins) infested lodgepole pine (Pinus contorta
Dougl.) barks were liquefied in phenol using sulfuric acid as the catalyst. Results showed that liquefaction conditions, such as reaction
time, reaction temperature, phenol/bark ratio, and catalyst loading had significant effects on the liquefaction yield, free phenol content of
the liquefied bark fraction and the properties of the unliquefied bark residues. Higher reaction temperature and prolonged reaction time
not only promoted the degradation of the bark components during the liquefaction but also induced recondensation reactions among the
degraded bark components. Higher phenol/bark ratio increased the bark liquefaction yield by retarding the recondensation reactions
among the degraded bark components. The liquefaction yield, free phenol content in the liquefied bark fraction and residues properties
were found to be mostly affected by the catalyst loading, followed by the reaction temperature, reaction time and phenol/bark ratio.