title: Citric acid crosslinking of paper products for improved high-humidity performance.
abstract: Fibre crosslinking with polycarboxylic acids can be used to improve certain properties of paper products, including wet tensile and compressive strength. In the present work it was proposed that citric acid (CA) crosslinks the cellulosic fibres of linerboard by self-catalysed esterification of cellulosic hydroxyl groups, which makes an additional catalyst unnecessary. An increase in CA dose or curing temperature increased linerboard compressive strength. In CA-treated corrugated board most of the applied CA was esterified with fibres while some CA thermolysis products were also present. A significant portion of the applied CA was unaccounted for. The deficit was attributed to thermolysis to give volatile anhydrides of unsaturated acids. Under cyclic humidity and static compressive loading, CA-treated corrugated boxes showed a greater than three-fold increase in resistance to compressive creep, showing that CA treatment can be used to extend the lifetime of corrugated boxes used for horticultural produce storage.
authors.affiliation: Scion, Te Papa Tipu Innovation Park, 49 Sala Street, Private Bag 3020, Rotorua, New Zealand. Electronic address: petri.widsten@scionresearch.com.
authors.forename: Petri
authors.initials: P
authors.lastname: Widsten
authors.forename: Nicola
authors.initials: N
authors.lastname: Dooley
authors.forename: Robin
authors.initials: R
authors.lastname: Parr
authors.forename: Jaworski
authors.initials: J
authors.lastname: Capricho
authors.forename: Ian
authors.initials: I
authors.lastname: Suckling
mesh_terms: D002384:Catalysis; D002482:Cellulose / Q000737:chemistry*; D019343:Citric Acid / Q000737:chemistry*; D019245:Compressive Strength; D006813:Humidity; D010209:Paper; D013696:Temperature; D013997:Time Factors
chemical_list: D019343:Citric Acid; D002482:Cellulose
keywords: Citric acid; Crosslinking; Fibre; Linerboard; Paper