Effect of drying, molding pressure, and strain rate on the flexural mechanical behavior of piassava (Attalea funifera Mart) fiber-polyester composites

The flexural strength of piassava-polyester composites was evaluated as a function of the molding force, strain rate and drying condition of the fibers. Composites with as-received fibers and with pre-dried fibers were fabricated, with mass fraction of fibers ranging from 0.20 to 0.40. The pre-drying of the fibers was shown to be the most relevant variable. Reduction of absorbed water before the incorporation of the fibers to the polyester matrix strongly affected the wetting of the fiber by the polymeric matrix, enhancing the fiber to matrix interaction. The composites manufactured with the pre-dried fibers show better flexural strength. Their behavior was independent of the molding pressure. The flexural strength of the composites decreased with the increase of the strain rate, but only minor variations were measured under the range of strain rates analyzed. The composites with the higher fiber loading, and pre-dried fibers, showed flexural strength values similar to the higher values reported for other lignocellulosic fiber-reinforced composites.