Cellulose foams from organosolv pulps with potential application as active packaging

Abstract This study demonstrates a green method to produce low-density cellulose using organosolv pretreated pulp, which also yields high-purity fractions of hemicelluloses and lignin that can be processed further to obtain different chemicals. A base-catalyzed organosolv pretreatment was employed on Norway spruce woodchips to release the cellulose fibrils, which were used to make low-density (20 kg/m 3 ) porous foams (98%). Sodium hydroxide was used as a catalyst, ranging from 0.25 to 1.5 M. The fibers obtained from these pretreatment conditions were characterized and correlated to the foam formation and properties. Furthermore, the samples were compared to foams made from commercially available unbleached and bleached sulfite pulp. A simple production technique was employed by rapidly agitating cellulose pulp with surfactant and additives to induce air into the system. The cellulose fibers arranged around the bubbles and formed a 3-D network upon drying. The lignin content and fiber aspect ratio of the organosolv fibers showed a positive correlation to the foam formation and stability. The foams presented good mechanical resistance (75%), and this property was tuned by the additives. High moisture adsorption tendency and comparably slower scavenging of antioxidant molecules were hypothesized to be due to the position of lignin in the interiors of the cell wall; these properties make the organosolv foams interesting for bioactive packaging applications.