title: Degradation of cellulose at the wet-dry interface. II. Study of oxidation reactions and effect of antioxidants.
abstract: To better understand the degradation of cellulose upon the formation of a tideline at the wet-dry interface when paper is suspended in water, the production of chemical species involved in oxidation reactions was studied. The quantitation of hydroperoxides and hydroxyl radicals was carried out in reverse phase chromatography using triphenylphosphine and terephthalic acid, respectively, as chemical probes. Both reactive oxygen species were found in the tideline immediately after its formation, in the range of micromoles and nanomoles per gram of paper, respectively. The results indicate that hydroxyl radicals form for the most part in paper before the tideline experiment, whereas hydroperoxides appear to be produced primarily during tideline formation. Iron sulfate impregnation of the paper raised the production of hydroperoxides. After hygrothermal aging in sealed vials the hydroxyl radical content in paper increased significantly. When aged together in the same vial, tideline samples strongly influenced the degradation of samples from other areas of the paper (multi-sample aging). Different types of antioxidants were added to the paper before the tideline experiment to investigate their effect on the oxidation reactions taking place. In samples treated with iron sulfate or artificially aged, the addition of Irgafos 168 (tris(2,4-ditert-butylphenyl) phosphate) and Tinuvin 292 (bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate) reduced the concentration of hydroperoxides and hydroxyl radicals, respectively. Tinuvin 292 was also found to considerably lower the rate of cellulose chain scission reactions during hygrothermal aging of the paper.
authors.affiliation: Centre de Recherche sur la Conservation des Collections, Muséum National d'Histoire Naturelle, CNRS-USR 3224, 36 rue Geoffroy-Saint-Hilaire, 75005 Paris, France. Electronic address: myung-joon.jeong@boku.ac.at.
authors.forename: Myung-Joon
authors.initials: MJ
authors.lastname: Jeong
authors.forename: Anne-Laurence
authors.initials: AL
authors.lastname: Dupont
authors.forename: E René
authors.initials: ER
authors.lastname: de la Rie
mesh_terms: D000975:Antioxidants / Q000737:chemistry*; D002482:Cellulose / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000737:chemistry; D017665:Hydroxyl Radical / Q000737:chemistry; D008970:Molecular Weight; D010084:Oxidation-Reduction; D010209:Paper; D013431:Sulfates / Q000737:chemistry; D013499:Surface Properties; D014867:Water / Q000737:chemistry
chemical_list: D000975:Antioxidants; D013431:Sulfates; D014867:Water; D017665:Hydroxyl Radical; D002482:Cellulose; D006861:Hydrogen Peroxide
keywords: Antioxidant; Cellulose; Hydroperoxide; Hydroxyl radical; Hygrothermal aging; Molar mass