title: The role of water in the degradation process of paper using1H HR-MAS NMR spectroscopy.
abstract: The thermodynamic properties of water are essential for determining the corresponding properties of every biosystem it interacts with. Indeed, the comprehension of hydration mechanisms is fundamental for the understanding and the control of paper degradation pathways induced by natural or artificial aging. In fact, the interactions between water and cellulose at the accessible sites within the fibres' complex structure are responsible for the rupture of hydrogen bonds and the consequent swelling of the cellulose fibres and consumption of the amorphous regions. In this paper we study the hydration process of cellulose in naturally and artificially aged paper samples by measuring the proton spin-lattice (T1) and spin-spin (T2) relaxation times of the macroscopic magnetization through nuclear magnetic resonance (NMR) experiments. The observed behaviour of T1and T2is quite complex and strictly dependent on the water content of paper samples. This has been interpreted as due to the occurrence of different mechanisms regulating the water-cellulose interaction within the fibres. Furthermore, we have measured T1as a function of the artificial aging time comparing the results with those measured on three paper samples dated back to the 15th century. We found that the evolution of T1in model papers artificially aged is correlated with that of ancient paper, providing therefore a way for estimating the degradation of cellulosic materials in terms of an equivalent time of artificial aging. These results provide fundamental information for industrial applications and for the preservation and restoration of cultural heritage materials based on cellulose such as ancient paper or textiles.
authors.affiliation: CNR-IPCF, Istituto per i Processi Chimico-Fisici del CNR di Messina, Viale F. Stagno d'Alcontres 37, 98158 Messina, Italy. ccorsaro@unime.it.
authors.forename: Carmelo
authors.identifier: http://orcid.org/0000-0002-1497-8750
authors.initials: C
authors.lastname: Corsaro
authors.affiliation: Consorzio Interuniversitario per lo Sviluppo dei Sistemi a Grande Interfase - CSGI, Via della Lastruccia 3, 50019 Sesto Fiorentino, Firenze, Italy.
authors.forename: Domenico
authors.initials: D
authors.lastname: Mallamace
authors.affiliation: Dipartimento MIFT, Sezione di Fisica, Universitá di Messina, Viale F. Stagno d'Alcontres 31, 98166 Messina, Italy.
authors.forename: Sebastiano
authors.identifier: http://orcid.org/0000-0003-0480-3321
authors.initials: S
authors.lastname: Vasi
authors.affiliation: Dip. di Fisica, "Sapienza" University of Rome, P.le A. Moro 2, 00185 Rome, Italy.
authors.forename: Luciano
authors.initials: L
authors.lastname: Pietronero
authors.affiliation: CNR-IPCF, Istituto per i Processi Chimico-Fisici del CNR di Messina, Viale F. Stagno d'Alcontres 37, 98158 Messina, Italy. ccorsaro@unime.it and Dipartimento MIFT, Sezione di Fisica, Universitá di Messina, Viale F. Stagno d'Alcontres 31, 98166 Messina, Italy and Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
authors.forename: Francesco
authors.initials: F
authors.lastname: Mallamace
authors.affiliation: Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, UOS Sapienza, Piazzale Aldo Moro 5, 00185 Roma, Italy. mauro.missori@isc.cnr.it.
authors.forename: Mauro
authors.initials: M
authors.lastname: Missori