The packaging industry, apart from the construction industry, is one of the largest consumers of wood in the world. The obtained cellulose fibers (usually in a kraft pulping process) are the basis for producing paper and corrugated cardboard. Despite the numerous advantages of this solution, primarily the relatively low price and the massive amount of fibers that come from recycling, one of the main disadvantages of paper is the sorption of liquid water and water contained in moist air. Water sorption significantly influences the quality and properties of paper and packaging products. The sorption processes are responsible for paper hygroexpansion and their dimensional instability. The strength properties of paper are substantially affected by water vapor sorption, while cyclic changes of air relative humidity induce mechanosorptive creep (e.g., Fellers, 2007). Increasing the moisture content of a paper product by 1% causes a decrease in the BCT (Box Crush Test), the primary indicator determining the strength of the packaging material, by 7% to 10% (Frank, 2014; Mark and Borch, 2001). The absorption of liquid water or water vapor from humid air and the resultant reduction in strength can render cellulose unsuitable in its natural form as a material for producing eco-friendly items intended for the food service sector. This includes applications like crafting plates and packaging for fast-food products that possess a notable water content. This topic is critical at present, given the strong trends, also sanctioned by the regulations in force in the European Union, aimed at eliminating plastics, particularly in single-use products. Some of these types of products are already included in the Directive of the European Parliament (Directive (EU) 2019/904 (June 5, 2019) on the reduction of the impact of certain plastic products on the environment.
In the study, model papers were produced and hydrophobized in bulk and on the surface through polysaccharides modified with methyltrimetoxysilane (MTMS). The following methods were used to assess the water-cellulose interaction: water contact angle, vapor sorption, liquid water sorption, and water penetration dynamics.
Keywords: cellulose hydrophobization, silylated starch, water sorption, water penetration dynamic
Authors
Waldemar Perdoch
Poznań University of Life Sciences, Faculty of Forestry and Wood Technology, Poland
Bartłomiej Mazela
Poznań University of Life Sciences, Faculty of Forestry and Wood Technology, Poland
Andreas Treu
Norwegian Institute of Bioeconomy Research, Norway
Tomasz Nowak
Poskładani.pl, Poland
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