High quality antique sheets of paper have been characterized by H-1 NMR relaxations and C-13 CP MAS spectra. Paper can be regarded as a bicomponent material made of cellulose and water plus a small amount of organic and inorganic impurities. Semicrystalline fibrous cellulose, rich in water, is present in the I-alpha and I-beta forms. The amorphous cellulose, with a low water content, contains a higher amount of paramagnetic Impurities and it is characterized by quite short 1(H) spin-lattice relaxations and by C-113 resonances with noticeable chemical shifts. Ad hoc tailored pulse sequences are able to produce C-13 CP MAS spectra in which only the amorphous content of paper is clearly observed. It is shown that water is fully bound to the cellulose lattice. It also seems reasonable to formulate the hypothesis that a larger concentration of paramagnetic ions is located in the amorphous fraction of highly degraded paper compared with paper in good condition.
Paci, M., Federici, C., Capitani, D., Perenze, N., Segre, A. (1995). NMR study of paper. CARBOHYDRATE POLYMERS, 26(4), 289-297 [10.1016/0144-8617(95)00011-U].
NMR study of paper
PACI, MAURIZIO;
1995-01-01
Abstract
High quality antique sheets of paper have been characterized by H-1 NMR relaxations and C-13 CP MAS spectra. Paper can be regarded as a bicomponent material made of cellulose and water plus a small amount of organic and inorganic impurities. Semicrystalline fibrous cellulose, rich in water, is present in the I-alpha and I-beta forms. The amorphous cellulose, with a low water content, contains a higher amount of paramagnetic Impurities and it is characterized by quite short 1(H) spin-lattice relaxations and by C-113 resonances with noticeable chemical shifts. Ad hoc tailored pulse sequences are able to produce C-13 CP MAS spectra in which only the amorphous content of paper is clearly observed. It is shown that water is fully bound to the cellulose lattice. It also seems reasonable to formulate the hypothesis that a larger concentration of paramagnetic ions is located in the amorphous fraction of highly degraded paper compared with paper in good condition.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
