Influence of multilayered films containing cellulose nanocrystals on the properties of japanese paper

Abstract

Cultural heritage objects are precious witnesses of the past, so our mission is not only to preserve them for future generations, but also make them available or open to the public. Among most fragile historic materials are paper-based materials. They are susceptible to various forms of damage and deterioration, and their preservation presents a challenging task for conservators. In recent years, the use of advanced materials with unique properties has been growing at an increasing rate, even in the traditionally slow-changing cultural heritage sector. This study models how historic paper would be affected by application of multiple coating layers containing different quantities of cellulose nanocrystals (CNCs). In our study, a 4 % CNCs aqueous suspension was used to treat the samples. In order to form a uniform layer, bar-coating method was used, and in addition, a specific layer thickness was formed in both single and multiple passes. The prepared samples were analysed for their optical properties (colour coordinates, yellowness, opacity, gloss), physical properties (Taber stiffness, weight, thickness) and surface properties (roughness). An increase of wet film deposit thickness (single layer applications) resulted in an increase of paper thickness, grammage, gloss, opacity, yellowness, the ΔE value and Taber stiffness, while its average surface roughness decreased. Multi-layer applications have gradually decreased paper thickness, while Taber stiffness remained unchanged.