Morphological, thermal and mechanical properties of ramie crystallites - Reinforced plasticized starch biocomposites

A series of environmentally friendly glycerol plasticized starch (PS) biocomposites were successfully prepared, using ramie cellulose nanocrystalites (RN) of 0-40 wt% as fillers. The ramie cellulose nanocrystalites, having lengths of 538.5±125.3 nm and diameters of 85.4±25.3 nm on average, were prepared from ramie fibers by acid hydrolysis. The morphology, thermal behavior and mechanical properties of the resulting composites were investigated by scanning electron microscopy, differential scanning thermal analysis, dynamic mechanical thermal analysis, and measurements of mechanical properties and water absorption. The results indicate that the synergistic interactions between fillers and between filler and PS matrix play a key role in reinforcing the composites. The PS/RN composites, conditioned at 50% relative humidity, increases, respectively, in both tensile strength and Young's modulus from 2.8 MPa for PS film to 6.9 MPa and from 56 MPa for PS film to 480 MPa with increasing RN content from 0 to 40 wt%. Further, incorporating RN fillers into PS matrix also leads to a decrease in water sensitivity for the PS based biocomposites.