Study of coatings for the protection of paper

Abstract

High humidity or direct contact with water are the main causes of degradation of cellulosic materials, such as paper and fabrics. Over the years a variety of protective products have been proposed such as carboxylate-alumoxanes sol-gel, titanium dioxide nanoparticles, modified copolymer lattices. The research, carried out in collaboration with the Smart Materials Department at the Italian Institute of Technology (IIT) in Genoa, had as main objective the development of formulations based on two water-repellent products commercially available: a fluoroacrylic co-polymer (Capstone® ST-100) and a polydimethylsiloxane (PDMS, Sylgard® 184). The purpose was to test their applicability to paper substrates, both ancient and modern, assessing morphological changes, water repellence, colorimetric changes even after artificial aging, water vapour permeability and hygroscopy. For this reason, different analytical techniques have been used, such as FTIR-ATR, colorimetric analysis, observations by SEM-EDX and light microscopy, contact angle measurement and mechanical strength. The applications of the products were carried out by spray and immersion achieving a systematization of the method and the choice of non-toxic solvents. Two of the four formulations tested were prepared with the addition of small percentages of silica nanoparticles (AEROSIL® R812) to observe the interactions with the polymer and the samples. The results were analysed both separately and through careful comparison in order to identify the best combination of formulation and method of application useful for future employment in the field of cultural heritage.