Production and characterization of hemp fiber reinforced epoxy matrix composites

In this study, the ability of hemp fibers, which are sustainable natural fibers, to be used as alternative reinforcement elements in composite material production and the change in material strength values of different angle arrangements were investigated. Hemp fibers provided in non-woven form were sized in equal sizes and arranged in a 20x20 cm mold with 90°, 60° and 45° angles and fed with epoxy matrix material. The specimens, which have 4 layers in total and each layer is laid at an angle opposite to the previous layer, are combined with the epoxy matrix and compressed under pressure. After compression, the specimens were left to harden in the open air for one day. Carbon fiber fibers, which are widely used in the production of composite materials, were also used in this study and the performances of the samples were analyzed in the study as a result of the reinforcement of hemp fibers with carbon fibers. The sandwich composite specimens produced by reinforcing carbon fiber with the same angles and lay-up methods were pressed under pressure and left to harden in the open air. In addition to these specimens, fibers sized as 1 cm and 2 cm based on the utilization of waste hemp fibers were produced by the same method using only hemp fiber and carbon fiber. Three-point bending and impact tests were performed on the produced specimens. Specimens were obtained in accordance with ASTM D790 standards, bending strengths were determined and microscopic images were obtained. When the results were examined, it was seen that the 90° hemp fiber + carbon fiber sample exhibited a higher bending strength value than the other samples. Only the flexural strength value of the carbon fiber sample was lower than the hemp reinforced sample. When the strength values of the samples produced in terms of the utilization of waste hemp fibers are examined, the shortening of the length of hemp fibers and reinforcement with carbon fiber caused an increase in flexural strength values. Impact tests were performed by producing specimens in accordance with ASTM D256 standards. According to the impact test results, it was observed that the fractures in the 45° angle specimens occurred on the shear plane, while the 90° hemp fiber + carbon fiber specimen gave the highest impact toughness value.