A comparative study on lyocell-fabric based all-cellulose composite laminates produced by different processes

摘要

Lyocell-fabric based all-cellulose composite (ACC) laminates were produced using a compression molding technique by four different routes using ionic liquid (1-butyl-3-methylimidazolium chloride) as solvent. Process I to Process III were used to produce cross-plied ACC laminates while unidirectional ACC laminates were produced by Process IV. The microstructures of the laminates were analyzed on the basis of SEM images and percentage void content. The relations between microstructure and mechanical properties of ACCs were studied on the basis of effect of dissolution time and different process techniques. The tensile and flexural properties of lyocell-ACCs manufactured through the present routes were also compared with conventional biocomposites. In all processes, longer dissolution times resulted in more reduction of internal void content as well as improved microstructure and properties. Compared to Process I, slightly better mechanical properties were achieved by Process II and Process III. An important improvement was observed in tensile and flexural properties for the unidirectional ACC produced using Process IV. The ACC-laminate prepared by Process III with 2 h dissolution time showed the highest inter-laminar adhesion strength (2.15 N/mm). The best tensile strength obtained was 102.6 MPa for the sample produced by Process IV with 1 h dissolution time. ACC-laminate prepared by Process IV with 2 h dissolution time showed the highest flexural strength, flexural modulus and Young's modulus which were 178.3 MPa, 11 and 4.2 GPa, respectively. These mechanical properties are better than those of most conventional biocomposites.