Solid State NMR Study of Polypropylene Composites Filled with Green Coconut Fiber

Dried green coconut fibers (GCF) consist of fibers of various length mixed with a fine powder. Both components can be separated by simple screening techniques, and the present paper summarizes an experimental study on the mechanical and molecular dynamic behaviors and the morphological aspect of green coconut fiber-reinforced polypropylene composites, with respect to the effects of content and granularity of the filler in the powder (0,841–0,500 mm) and fiber (10 mm) forms. All compounds were prepared in an internal mixer at 170°C, 60 rpm for 8 min. It was observed that the flexural modulus increases with increasing fiber content, either in powder or fiber forms. Impact tests show that fiber-filled composites have greater impact strength than powder-filled composites. The results obtained by low-field NMR show that the stiffness of composites decreases with higher fiber loading, due to the poor compatibility between fibers and matrix. The morphology of the system was studied by SEM analysis. In general, composites with fiber showed better properties than those with powder.