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Three recent updates (Emsley, Ding & Wang and Calvini) of the old Ekenstam equation applied to the degradation of cellulose have been analysed using (1) internal coherence, (2) boundary conditions and (3) physical meaning. The Ekenstam, Emsley and Calvini equations belong to the same class (random scissions), while the Ding and Wang equation appears to be tracking a different mechanism (peeling/stopping). The analysis allowed a deeper insight into these equations as well as some upgrades of their original versions.

In this study, several deteriorated pressure sensitive adhesive tapes (PSATs) applied in the past for repairing ripped paper documents of 19th century and books of 20th century were analyzed by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy technique. The comparison of FTIR spectra of the old tapes with those of some commercially available tapes subjected to accelerated aging allowed us to identify, in a fast and nondestructive way, the main classes of old tapes on the basis of their backing (cellophane, cellulose acetate, polyvinyl chloride and polypropylene) and adhesive (natural rubber, synthetic rubber and acrylic polymer) compositions. This procedure's results were very useful to the paper restorers and conservators, who will have the possibility of choosing the most appropriate conservation treatment for the removal of pressure sensitive adhesive tapes that can be found on many paper documents.

The kinetics of periodate oxidation of cellulose was followed by exploiting the β-alkoxy degradation of oxidised units in alkaline medium, that brings about a decrease of viscometric degree of polymerisation. The parallel strong weight loss after NaOH treatment indicates a non-random mechanism of oxidation. The obtained results are interpreted on the basis of an appositely derived kinetic model that can be applied to other mechanisms of bulk and surface degradation.

The meaning of the Ekenstam equation (1/DP − 1/DP°) = kt is shortly discussed. Several misleading statements about its application to cellulose hydrolysis are underlined in order to improve the reliability of kinetic analyses. To this end, some further simple analyses are suggested to the experimentalists.

A sample set of model graded papers containing known organic and inorganic components was used to culture an Aspergillus terreus strain able to produce acidic metabolites and cellulolytic enzymes. This study set out to document the biogenic formation of calcium oxalate crystals, as a consequence of fungal activity and growth, on a range of paper samples. Scanning electron microscopy and FTIR spectroscopy techniques were employed to achieve this end. Bioleaching processes induced by fungi on carbonate used in the manufacture of paper, together with the capacity of fungi to produce - very rapidly - significant biogenesis of monohydrate and dihydrate calcium oxalate crystals on the surface of papers, were investigated. SEM images of calcium containing paper samples disclosed a very clear difference in the pattern of inorganic material distribution when areas spoiled by fungi and those not affected by fungal growth were compared. In addition, the FTIR spectrum of CaCO(3) sized paper clearly demonstrated, following fungal growth, the FTIR absorbance of fungus and calcium oxalate, together with the disappearance of carbonate bands. (C) 2010 Elsevier Ltd. All rights reserved.

International audience; Water cleaning of paper leaves is a preliminary step in many customary deacidification treatments of ancient books in conservation workshops. Usually, the washing solutions are considered “waste waters” and they are thrown away. In this work, an analytical protocol for the analysis of wash waters for the assessment of the conservation state of ancient books is proposed. Wash waters of leaves under different conservation conditions of a 16th-century- rinted book were investigated using UV-Vis, IR, Raman, NMR, EPR, XRF, ESI-MS, ICP-MS, CE-PDA and elemental microanalysis. Analysis of the wash water extracts allowed one to identify a large number of degradation by-products, ranging from low-molecular mass organic acids to cellulose oligomers. Reasons for the very different conservation conditions of the leaves emerged, indicating that wash water analysis provides a deep insight into the conservation state and composition of leaves as well as degradation reactions occurred on them

Paper lamination is a widely used method to consolidate fragile documents. Previous studies have presented a new method of lamination that allows the consolidation of documents before undertaking aqueous treatments. In this method a thin Japanese paper coated with an acrylic resin is applied on the fragile document by means of a heated press. In this work we optimised the preparation of the lamination sheets as well as the working procedures, and we were able to establish that our laboratory-made specimens are chemically stable, easily reversible and permeable to aqueous solutions. The latest property is of particular importance, since it allows a subsequent aqueous deacidification even for fragile documents. The laminated paper documents were further analysed by means of colorimetry and FTIR spectroscopy before and after accelerated ageing as well as by determination of the alkali reserve left on the coated paper, in order to compare our lamination method with other commercially available lamination sheets.

Periodate oxycellulose was subjected to alkaline hydrolysis at room temperature in both homogeneous (cupriethylenediamine) and heterogeneous (sodium hydroxide) medium, and the degradation kinetics was followed for nearly three months. By comparing the obtained results with the degradation kinetics of both hydrocellulose and periodate oxycellulose reduced with tert-butylamine borane, it was demonstrated that the β-alkoxy fragmentation of oxidised sites is a very fast reaction, which reaches completeness during the preparation of samples for viscometric analyses. The subsequent degradation is due to other mechanisms, such as autoxidation and peeling. A comparison between the degrees of polymerisation of periodate oxycellulose before and after its reduction allows the quantitative determination of dialdehyde groups, without the interference of reducing end groups. Although this technique might not be valid for other kinds of oxycellulose, it supplies a simple and fast method for the analysis of mildly oxidised cellulose.

In this work, we present a wide-range spectrochemical analysis of the degradation products from naturally aged paper. The samples obtained from wash waters used during the de-acidification treatment of leaves from a 16th-century-printed book were analysed through NMR, IR, Raman UV/Vis, EPR and X-ray fluorescence (XRF) spectroscopy and HPLC-MS and inductively coupled plasma (ICP) analysis. By these methods we also studied some of the previous samples treated by acidification (sample AP) and catalytic hydrogenation (sample HP). Crossing all the data, we obtained precise indications about the main functional groups occurring on the degraded, water-soluble cellulose oligomers. These results point out that the chromophores responsible for browning are conjugated carbonyl and carboxyl compounds. As a whole, we show that the analysis of wash waters, used in the usual conservation treatments of paper de-acidification, gives much valuable information about both the conservation state of the book and the degradation reactions occurring on the leaves, due to the huge amount of cellulose by-products contained in the samples. We propose therefore this procedure as a new very convenient general method to obtain precious and normally unavailable information on the cellulose degradation by-products from naturally aged paper.

Des etudes experimentales realisees a l'aide de solutions aqueuses de percarbonate de sodium [2Na 2 CO 3 3H 2 O 2 ] incitent a recommander l'utilisation de ce moyen de blanchiment dans le traitement des papiers jaunis, decolores et taches. Le choix de ce produit est justifie par la bonne stabilite chimique presentee par l'agent chimique reactif qu'est le percarbonate solide lorsqu'on le compare aux solutions d'hydrogene peroxyde (eau oxygenee) frequemment utilisees dans la restauration du papier. L'objet de cette etude consiste a evaluer les avantages et les inconvenients du traitement d'echantillons de papier prealablement oxydes au percarbonate de sodium. Les echantillons soumis a l'experience ont ete obtenus par oxydation du papier de Whatman N° 1 a l'aide de periodate de sodium. Par ailleurs des papiers de pâte mecanique, jaunis et taches, vieillis naturellement ont ete egalement traites. Le mecanisme chimique de la procedure de blanchiment a partielement ete elucide au moyen de la methode FTIR ainsi que d'autre part selon des criteres d'analyse gravimetriques et viscosimetriques. Apres le traitement de blanchiment les echantillons analyses ont ete places dans des solutions de chlorure de calcium afin d'eliminer l'effet destructeur des ions de sodium apres le traitement d'une part, et d'introduire directement une reserve alcaline sous forme de carbonate de calcium dans la matrice du papier d'autre part. Les resultats obtenus jusqu'a present demontrent que le percarbonate de sodium pourrait, apres l'etablissement d'une methode pratique d'utilisation, representer une alternative adequate au peroxyde d'hydrogene (eau oxygenee) pour le blanchiment de papiers anciens de pâte mecanique jaunis et taches. Le percarbonate de sodium presente egalement d'autres avantages, notamment en raison de sa stabilite chimique et de la securite de son emploi ainsi que pour sa bonne degradabilite.

The kinetics of cellulose degradation was analysed by means of a two-stage model, characterised by an autoretardant and autocatalytic regime, later tempered by the consumption of glycosidic bonds in the amorphous regions. The proposed model explains the effects on the kinetic equations of different modes of ageing (acid hydrolysis, ageing in ventilated oven or sealed vessels), initial oxidation of cellulose and experimental procedures (with or without reduction of oxidised groups). The autoretardant branch can be analysed in a quantitative way, while the integration of the non-linear autocatalytic branch is allowed in some cases, characterised by the decrease of pH and/or emission of acid volatile organic compounds (VOCs). Most of the controversial results of the literature can be easily explained, but the proposed model offers also a guide for further studies on the kinetics of cellulose degradation.

Le processsus de restauration de documents historiques sur papier est soumis a de fortes contraintes en ce qui concerne un eventuel mode de traitement a base de produits chimiques et de solvants. Au cours de la presente etude les auteurs se sont penches sur l'effet fongicide du proponiate de calcium. Cette liaison aussi proposee comme reactif deoydant peut etre utilisee dans une solution aqueuse ou encore dans une solution alcoolique. L'effet fongicide du proponiate de calcium a ete compare avec un produit sous forme de spray commercialise a base de 4-hydroxybenzoate et de propyle 4-hydroxybenzoate. Une partie des tests a ete effectuee sur des organismes ayant pu etre isoles de taches d'humidite de papiers historiques. Une autre serie a ete faite sur des souches provenant d'une plaque de verre posee sur du papier pique par les taches d'humidite, ceci en tenant compte des positions du mycelium sur la plaque avec laquelle les taches d'humidite sur le plapier etaient couvertes. On a pu ainsi identifier dix especes generant du mycelium, dont cinq especes de penicillium De plus, on a reussi a identifier une espece de levure. Les fongicides ayant ete soumis aux tests se sont reveles etre tres differents sur le plan de leur efficacite a entraver la croissance de micro-organismes. Les auteurs ont prouve qu'une solution saturee de proponiate de calcium (3,5g/l) dans de l'ethanol avait un effet fongicide significatif.

Afin de determiner les facteurs cles responsables de la deterioration du papier place dans un environnement clos, ou range dans des rayons, un modele autocatalyctique de degradation en conteneurs scelles a ete cree. En raison de la non-linearite du modele une solution analytique ne peut etre trouvee si facilement mais une simulation sur ordinateur indique de facon qualitative que l'acidite initiale du papier exerce une une influence sur la forme du deroulement cinetique alors que l'ampleur d'un accroissement de composes acides volatiles (VOCs) provoque un accroissement de la deterioration. Nos resultats demontrent que l'acidite initiale et le mecanisme chimique d'oxydation devraient etre pris en consideration dans les recherches, plutot que le degre de polymerisation, tant en ce qui concerne le processus de vieillissement accelere que celui du vieillissement naturel du papier dans des environnements clos, c'est-a-dire non ventiles (non aeres).

La cinetique de la degradation du papier a ete brievement reconsideree et remise a jour afin de mettre en evidence les facteurs essentiels qui avaient ete (et qui sont encore) largement negliges lors de l'interpretation des resultats experimentaux. Un simple re-examen des donnees de la litterature revele le caractere discutable de maintes declarations faites dans le domaine de la recherche relative a la conservation du papier. On a demontre en particulier que les techniques du vieillissement accelere ne permettent pas de predire l'esperance de vie du papier, comme le met en evidence la structure exponentielle de l'equation d'Arrhenius. Il apparait par ailleurs que certains resultats obtenus lors d'analyses viscosimetriques aient ete mal interpretes car lors de la planification des experiences aucune difference n'avait ete faite entre la degradation actuelle (hydrolytique) et la degradation potentielle (oxydative) de la cellulose. Enfin l'ordre pseudo-zero de la cinetique de la degradation conduit a des declarations discutables car la plupart des mecanismes de degradation du papier ne se conforment pas a ce modele simple. Les resultats de la recherche dans le domaine de la conservation du papier devraient etre partiellement revises.

The kinetics of periodate oxidation of cellulose was followed through the alkaline degradation of the dialdehyde groups by measuring the viscometric degree of polymerisation and the alkali consumption. The obtained results show that a fast but limited attack of periodate occurs in the amorphous region of cellulose, causing the decrease of degree of polymerisation to its levelling-off value. The alkali consumption indicates at least two further slower reactions, that lead to the asymptotic complete oxidation of cellulose units. With the pseudo first-order approximation, the oxidation half-time of these three reactions can be calculated, corresponding to 1.2, 20 and 854 h respectively. In spite of the high oxidation of the analysed samples (up to about 46%), the residue after alkaline degradation shows a relatively high value of degree of polymerisation rather than the narrow molecular weight distribution of oligomers expected from a random oxidation, thus indicating that periodate oxidises cellulose in isolated domains. The sequence of analyses over the same sample utilised in this work (titrimetry, weight loss and viscometry), performed at room temperature in mild conditions, makes it possible to investigate the topochemistry of oxidation of paper and textiles of historic and artistic value with microdistructive techniques on a single, very small fragment of material.

Cellulose paper (Whatman no.1, chromatographic grade) was oxidised with 0.1 M sodium metaperiodate at different oxidation levels (0–11 days at room temperature), and analysed with FTIR before and after chemical treatments (reduction, further oxidation, alkaline hydrolysis). The deconvolution of infrared data allowed us to verify that periodate oxidises cellulose in isolated domains, leading to the decrease of crystallinity, in agreement with the results of wide angle X-ray scattering (WAXS). In particular, the alkaline hydrolysis (β-alkoxy fragmentation) followed by mild acid treatment removed the oxidised groups and recovered most of the crystallinity of cellulose, as determined by the FTIR crystallinity index.

Paper lamination is a widely known method to consolidate fragile and brittle documents. Since the loss of mechanical strength of paper documents is almost completely due to their acidity, the procedure generally adopted by restorers consists of an aqueous treatment of deacidification followed by consolidation. The drawback of this method is due to the loss of paper fragments during the deacidification step, that must be therefore accurately controlled. Some preliminary experiments showed that a better and faster practice would be the lamination of paper documents with a water-resistant sheet before their immersion in the deacidification bath. The aim of this work is to evaluate the permeability, chemical stability and reversibility of the lamination sheets coated with two commercially available acrylic resins. From both gravimetric and FTIR analyses it appeared that slight modifications of the acrylic monomers led to different properties, and this behaviour can be exploited to improve the properties of lamination sheets in order to set up a reliable method of aqueous mass deacidification.

Les spectres infrarouges des echantillons de papier montrent souvent de nombreuses bandes qui se chevauchent de facon tres significative aux alentours de 1400-1900 cm. La deconvolution numerique revele les informations sous-jacentes comme l'ont demontre certains exemples de deconvolution effectuee sur des echantillons anciens de papier original ainsi que sur des echantillons de papier specialement prepares. Grâce a la technique de deconvolution numerique il est possible de detecter l'absorption d'infrarouge par les groupes oxydes (conjugues ou non conjugues) dans la molecule de cellulose, ainsi que dans la gelatine, la colophane et la lignine et ceci meme en presence de larges bandes provoquees par absorption d'eau a -1630 cm. La technique de deconvolution permet d'identifier approximativement le mecanisme de degradation qui entraine le jaunissement et le brunissement des echantillons de papier.

Des echantillons de papier de cellulose contenant du FeCl 3 et du CuCl 2 ont ete soumis a une analyse FTIR avant et apres le vieillissement accelere a 90+/-10°C (technique des tubes scelles). On a pu constater qu'une forte hydrolyse et une deshydratation des chaines cellulosiques avec formation de liaison double de C4-C5 et d'une oxydation de C6 sont les phenomenes essentiels observes lors de la degradation de FE(III). Cu(II) oxyde les groupes C2- et C3-OH en aldehydes et carboxyles en entrainant une cassure des composes cycliques qui hydrolyse et oxyde le groupe C4-OR avec formation de C4-C6 β-ceto-aldehyde ou β-ceto-acide. Parmi les bandes de deconvolution FTIR du domaine situe entre 1250 et 1850 cm -1 on attribue le signal 1660 cm -1 au groupe insature de C=C-cO et le signal 1612-1622 cm -1 au groupe CO-C-CO (forme chelatee de tautomerie ceto-enolique). Ces bandes qui ne peuvent etre detectees qu'a l'aide de la technique de deconvolution apparaissent plus distinctement que celles de groupes libres (non-lies) au-dela de 1700 cm -1 .

Dans cette etude deux echantillons de cellulose pure a differents degres de polymerisation ont ete soumis a une degradation oxydante par un agent specifique (sodium metaperiodate) et par un agent non-specifique (sodium hypochlorite). Le processus de degradation a ete controle en effectuant des mesures de la viscosite afin de determiner le degre de polymerisation. L'etude a demontre que les deux echantillons ont un comportement similaire et que le processus de degradation aboutit a la meme valeur limite du degre de polymerisation. Les echantillons ont ete egalement soumis a une spectroscopie FTIR et les resultats ont mis en evidence que differents groupes fonctionnels proviennent du processus d'oxydation.