Packaging and packing materials have an important role in the transport and storage of goods. However, due to the widespread use of fossil, non-biodegradable raw materials, packaging is a topic of environmental discussions. Several packages consist of materials, which cannot be recycled in closed recycling loops. Instead, they are thermally recycled or enter the environment.<br/>Paper as bio-based, biodegradable and fully recyclable material plays an important role in the packaging sector due to the sustainability of the material, its flexibility and its high specific strength. However, in addition to the advantages, paper also has weaknesses in terms of certain functionalities. It does not have high stiffness, is not waterproof, and does not provide a barrier to the migration of gaseous substances. These weaknesses have so far been overcome by coating paper or making laminates of paper and other materials.<br/>An alternative to such multi-material solutions could be All-Cellulose Composite (ACC). These are made of cellulosic fibers through a conversion process. The result is a composite material in which the matrix and the fiber reinforcement are made of cellulosic materials. The first materials corresponding to an ACC according to today's definition has been produced since the mid-19th century by impregnating raw papers made of cotton fibers with zinc chloride solution or sulfuric acid on an industrial scale. In more recent publications, various alternative solvent systems have been investigated on a laboratory scale and their influence on the mechanical properties described. However, with regard to wet strength and especially barrier properties, there are only a few publications.<br/>In this study, a solvent system consisting of NaOH and Urea was investigated. This solvent system enables rapid dissolution of the cellulose, is environmentally compatible and comparatively inexpensive. Various cellulosic materials were used as starting material for ACC production. The cellulosic papers were immersed in the solvent system for short period of time (1-2 s) and the reaction was stopped by adding water. The cellulosic raw materials and process parameters were varied to study the interactions with the ACC material properties. It was found that the tensile strength, wet strength and barrier effect could be significantly improved by conversion of cellulosic paper to ACC. In addition, by modifying a paper machine, it was shown that a continuous production of ACC is possible.

All-cellulose composite: A contribution to the understanding of the interaction between manufacturing parameters and material properties

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