Composites of Polycaprolactone with Cellulose Fibers: Morphological and Mechanical Evaluation

Abstract

SummaryIn the present work, alkaline followed by acid treatment was performed on curauá and jute fibers to remove the amorphous portion and to aid fibrillation. X‐ray diffraction revealed that the chemical treatments led to better organization of cellulose microfibrils and consequently an increase in their crystallinity index. Thermogravimetric analysis showed a slight decrease in thermal stability of the chemically treated cellulose fibers, however not to the point of preventing their use as filler in polycaprolactone (PCL) matrixes. SEM micrographs revealed that the chemical treatments reduced the fibers’ dimensions. Composites of PCL were prepared in a twin‐screw extruder, adding different cellulose fibers (treated curauá and jute fibers, commercial cellulose and amorphized cellulose) at 2, 5 and 10 wt.%, maintaining the processing time constant. The results suggest that increasing the fiber crystallinity leads to increased nucleation effect for PCL and that fiber with low crystallinity (amorphized) hinders crystallization of the matrix. Moreover, shorter fibers promote higher nucleation effect in the PCL matrix. SEM micrographs also revealed the presence of nanofibrillated cellulose dispersed in PCL containing chemically treated curauá and jute fibers. Finally, dynamic‐mechanical analysis (DMA) showed an increase in modulus and Tg of the composites containing 5 wt.% fibers.