The Upcycling of Natural Waste Materials: Alternative Fibers in Papermaking

Abstract

In the actual scenario, characterised by a global crisis, sustainability is not a minor player; it has a crucial role in the global outlook. Sustainability at the environmental level evolves in recycling, reusing, upcycling, and no squandering policies. Nowadays, the incessant, excessive, and growing use of plastic has a strong impact on global warming and represents a threat to the Oceans and the Planet. The paper industry can play a crucial role in addressing this emergency, by substituting mostly or totally (where it is possible) this impacting material. To confer paper materials the same plastic resistances, some additives could be used. In detail, the feasibility of upcycling silk waste was investigated and paper products containing silk fibers were formulated to realize worthy substitutes for plastic materials. These alternative fibers were inserted as a filler (20%wt. and 30% wt) in the cellulosic matrix and the resulting suspension was used to produce special papers for packaging. Silk, in both cases, was subjected to a chemical pretreatment with NaOH before paper sheet formation, which guaranteed an appropriate silk-cellulose interaction, without compromising the final chemichal-physical properties. Moreover, the sheets were subjected to non-destructive and destructive testing, which confirmed respectively their high-quality degree and good mechanical resistances. Silk confers special characteristics, in particular, the resulting sheets with silk were fluffier to the touch than the reference in pure cellulose. The resulting materials can be used as semi-finished products to obtain more sustainable paper-based packaging materials and promote a plastic-to-paper transition. Keywords: Upcycling; Waste; Pretreatment; Sustainability, Paper-Based Pack