All‐cellulose composites from pineapple leaf microfibers: Structural, thermal, and mechanical properties

Pineapple leaf microfibers (PALM) were used to prepare all‐cellulose composites using the surface selective dissolution method. Effect of dissolution times on mechanical and physical properties of the all‐cellulose composites was investigated. The structural transformation from cellulose I to cellulose II was observed when the fibers were dissolved in a mixed solution of lithium chloride (LiCl) and N,N ‐dimethylacetamide (DMAc). Values of 42.8 MPa and 1.2 GPa for tensile strength and Young's modulus, respectively, were obtained from the composites with 120 min dissolution time in the LiCl/DMAc solution, whereas the tensile strength and Young's modulus of the undissolved PALM mats were found to be only 1.5 MPa and 0.1 GPa, respectively. The failure mechanism of the composites was changed from the fiber pull‐out to the fiber breakage when the dissolution time was longer. However, lower thermal stability and degree of crystallinity of the composites were caused by the change of the cellulose structure. The composites prepared in this work can be called as biodegradable materials, and could be the potential candidates to replace nonbiodegradable materials. POLYM. COMPOS., 39:895–903, 2018. © 2016 Society of Plastics Engineers