The Effect of Volume Fraction Variation on the Tensile Strength of Polyester Composites Reinforced with Praksok Leaf Fiber (Cordyline australis).

Abstract

In everyday life, the use of composite materials in engineering is increasing. This is because the nature of composite materials has advantages compared to conventional materials. One of the natural fibers that can be used as a raw material for composites is praksok fiber (Cordyline australis). Praksok fiber has good strength value and has high economic value so that it can be used as a substitute for synthetic fibers. This study aims to analyze how the effect of volume fraction variations on tensile strength in composites using polyester resin reinforced with praksok leaf fiber (Cordyline australis) supported by 10% NaOH alkalization treatment for 2 hours which is printed using the Hand Lay-Up method. Using polyester resin as a matrix that will support praksok fiber as a composite. The fiber direction used is random with a 1 cm cut, with variations in the fiber volume used in the specimen being 15%, 20%, and 25%. The testing tool used is the Tensilon RTG-1250 Tensile Tester with ASTM D638 as its standard. The test results show that the highest tensile stress value is found in the variation of the fiber volume fraction of 20% with a tensile stress value of 22.340 MPa, and there is a decrease in tensile stress in the variation of the fiber volume fraction of 25%. The highest tensile strain is also obtained by the variation of the fiber volume fraction of 20% with a value of 3.752% and there is a decrease in the strain value in the variation of the fiber volume fraction of 25% with a tensile strain value of 2.846%. Meanwhile, the highest modulus of elasticity value is obtained by the variation of the fiber volume fraction of 15% with a modulus of elasticity value of 0.704 GPA, then followed by the fiber volume fraction of 20% with a value of 0.615 GPA and the fiber volume fraction of 25% with a value of 0.591 GPA. The lowest value of each tensile stress, tensile strain, and modulus of elasticity test is obtained by the variation of the resin without reinforcement. This indicates that the addition of praksok fiber as a reinforcing material is effective in increasing the strength of the composite material. It is also reinforced by the results of SEM photos which show that the interfacial bonding of polyester composite specimens reinforced with praksok leaves (Cordyline australis) is better than without the addition of praksok leaf fiber