The Effect of Fiber Volume Fraction on the Mechanical and Morphological Properties of Fiber Cissus Sicyoides Reinforced Epoxy Composites

Pengaruh Fraksi Volume Serat Terhadap Sifat Mekanik dan Morfologi Komposit Epoxy Diperkuat Serat Cissus Sicyoides

Abstrak

Abstract: This study aims to analyze the effect of varying fiber volume fractions (2.5%, 7.5%, 10.5%, 15%, and 20%) on the tensile strength of the composite, with a total of 30 specimens prepared (15 specimens for tensile testing and 15 specimens for flexural testing) in accordance with ASTM D3039 and ASTM D790 testing standards. The composites were fabricated using the manual hand lay-up method, and microstructural analysis was performed using Scanning Electron Microscopy (SEM). The tensile test results showed that increasing the fiber volume fraction did not improve the tensile strength of the composites. The tensile stress values generally decreased sequentially from a fiber volume fraction of 2.5% to 20%, with the highest value at 17.964 MPa and the lowest at 8.824 MPa. SEM analysis indicates that this decrease is caused by poor fiber-matrix interface quality, as evidenced by the presence of a distinct gap between the fiber walls and the matrix. Conversely, in flexural testing, an increase in the fiber volume fraction generally increased the composite’s flexural strength, reaching a maximum value of 35.391 MPa at a 20% fraction. However, a drastic decrease occurred at a 15% fraction, with a minimum value of 9.483 MPa, due to a suboptimal matrix composition and the formation of excessive voids resulting from the manual manufacturing process. Soaking the fibers in a NaOH solution effectively removes oil, wax, lignin, and hemicellulose to strengthen the interfacial bonds, thereby optimizing the transfer of mechanical stress from the matrix to the fibers in subsequent studies.