Effect of Particle Size, Fiber Content and Compatibilizer on the Long-term Water Absorption and Thickness Swelling Behavior of Reed Flour/Polypropylene Composites

Reed (Phalaris sp.) flour was used to produce natural fiber polypropylene composites and effects of particle size, compatibilizer, and fiber content on the physical properties of the produced composites were evaluated. The particle sizes ranged from 40 mesh to smaller than 100 mesh sizes and fiber contents were 60% and 70% by weight. Composites were made through the extrusion process. Particle size proved to have very significant effects on both water absorption and thickness swelling of the composite formulations. The lowest water absorption and thickness swelling values were obtained at the lower fiber content and smallest particle size. Water diffusion coefficients were also smaller for smaller particle sizes and at lower fiber contents. The effect of compatibilzer was positive in terms of enhancing the dimensional stability of the composites. Composites containing the smallest particle size exhibited different water absorption and thickness swelling behaviors as seen in their considerably longer time required to reach maximum values.