DEVELOPMENT OF A MULTIFUNCTIONAL POLYSILOXANE BASED CONSERVATION TREATMENT FOR BRITTLE PAPER: THE APPLICATION TO AGED NEWSPRINT
Résumé
Developing a methodology allowing the simultaneous deacidification and strengthening of paper is of a great interest for restoration and conservation purposes. To achieve this goal, a conservation treatment based on the random copolymerization of a tri-alkoxysilane with a di-alkoxysilane was developed, the latter creating linear segments inside the 3D-network. This leads to the formation of a flexible copolymer network associated to paper and imparts its mechanical strengthening. For the purpose of deacidification the alkoxysilanes chosen also contain one amine function. The molar proportions of tri- and di- alkoxysilanes can be modified to adjust rigidity or flexibility to the system, which enables the treatment to be adapted to papers of various composition and states of degradation. Two application methods, immersion and spray, can be used at ambient temperature and pressure. In a previous study, the development of the treatments was carried out on pure cotton cellulose paper [1]. However, most papers, in particular newsprint paper, are made of mixed fibers from different pulping processes and often contain additives such as fillers and sizing. Papers containing various proportions of mechanical and chemical wood pulp and additives were therefore chosen and artificially aged in order to better simulate a natural degradation state. Different treatments were then applied and the main physicochemical properties of treated papers were studied (double fold resistance, zero-span tensile strength, alkaline reserve). The results showed that deacidification and alkaline reserve deposition were satisfactory and that efficient strengthening of the papers was achieved to various extents, depending on the copolymers used, their proportion and the type of paper. The stability of the treatments with time was evaluated using artificial aging, following which the most adequate treatment was applied to a degraded newsprint paper (1922) and its properties measured.
References
[1] C. Piovesan, A.-L. Dupont, I. Fabre-Francke, O. Fichet, B. Lavedrine, H. Cheradame, Cellulose 21 (2014) 705-715