Effect of the dissolution time on the structure and properties of lyocell‐fabric‐based all‐cellulose composite laminates

Abstract

In this study, all-cellulose composite laminates were prepared from lyocell fabric with ionic liquid (1-butyl-3-methyl imidazolium chloride), a conventional hand layup method, and compression molding. Eight layers of lyocell fabric, which were impregnated with ionic liquid, were stacked symmetrically and hot-pressed under compression molding for various times; this resulted in the partial dissolution of the surface of the lyocell fibers. The dissolved cellulose held the laminas together and resulted in a consolidated laminate. Finally, the prepared laminate was impregnated in water to remove the ionic liquid and to regenerate a matrix phase in situ; this was followed by hot-press drying. Optical microscopy and scanning electron microscopy studies were used to analyze composite structures. With increasing dissolution time, the void content in the composites decreased, and the interlaminar adhesion improved. For LC-2h and LC-3h, the highest tensile strength and modulus values obtained were 48.

All-Cellulose Composites: A Review of Recent Studies on Structure, Properties and Applications

“…Regenerated cellulose fibers mostly consist of cellulose II. One of the most important parameters that makes regenerated fibers favorable in ACC production on a commercial scale is their uniformity in properties and shapes between different batches [60,78,94,[115][116][117][118]. Adak et al [117] manufactured Lyocell-based ACCs via a compression molding technique using IL (1-butyl-3-methylimidazolium chloride) as a solvent.…”

Processing of Cellulose Using Ionic Liquids

“…In a subsequent coagulation process, for example, in water, the IL is removed and the cellulosic matrix is regenerated. While different routes for the preparation of ACCs with derivatizing and non‐derivatizing solvent systems are described in literature, dimethylacetamide/lithium chloride (DMAc/LiCl) besides NMMO and ILs is the most frequently used as the solvent system. Generally, there are two processing paths for the preparation of ACCs.…”

Ionic Liquid Approach Toward Manufacture and Full Recycling of All‐Cellulose Composites

“…On the other hand, as single‐origin composites, they promise a very easy recycling, as the fiber and the matrix components do not have to be separated in order to obtain pure materials. In fact, all‐cellulose composites (ACCs), as completely cellulose‐based composites, show mechanical properties superior to classical biocomposites . For their manufacture, the nonmeltable cellulose is processed from solution (=matrix precursor) in order to form the composite's matrix.…”

“…From an ecological point of view, ACCs are much more sustainable than traditional NFRPs because they are biodegradable, and they can potentially be recycled by redissolution in a suitable solvent for a subsequent composite manufacture (vide infra). So far, ionic liquids (ILs) have been used in single‐step processes . Generally, the manufacture of ACCs with the aid of ILs is an environmentally friendly, resource efficient way for the processing of cellulose, which is infusible and difficult to dissolve.…”