Synergistic interactions for saving energy and promoting the co-pyrolysis of polylactic acid and wood flour

Abstract

The rapid growth of polylactic acid (PLA) production and the slow hydrolysis rate make PLA a potential environmental pollutant. In order to make better reuse of the waste PLA in energy fields and solve the potential pollutant, PLA/wood flour (WF) compounds in all different proportions were co-pyrolyzed to study the co-pyrolysis behavior in terms of energy and products. The apparent activation energy of the 50%wtWF50%wtPLA compounds during co-pyrolysis decreased by 28% than PLA and 29.4% than WF. In addition, the pyrolysis of PLA provided additional energy for the co-pyrolysis of compounds which reduced the external input energy. The chemical reactions between WF and PLA during co-pyrolysis could be called synergistic interactions which promoted the free radical reaction of PLA and lead to the increase of lactide production. The yield of the harmful acetaldehyde reduced by 85.9% in the co-pyrolysis of 25%wtWF75%wtPLA compounds. In addition, the production of small molecular benzene ring substances was increased. For example, the phenol yield increased by 31.3% in the co-pyrolysis of 25%wtWF75%wtPLA compounds. The carbon number distribution of the main products was mainly concentrated on C5–C7 which was better for the reuse of bio-fuels during co-pyrolysis.