Estimation of Mechanical and Thermal Properties of Glass and Sisal Fiber Composites with Polyester Resin Matrix

In this study, hybrid composites were produced using a manual layup technique, incorporating natural fibers as reinforcements, namely sisal (S) and glass (G) fibers, combined with a polyester resin matrix. The manufacturing process maintained a constant 30 wt% of total fiber content while varying the weight ratios of glass and sisal fibers. Test specimens adhering to ASTM standards were prepared. The primary focus of this investigation was on the development of sisal–glass fiber-reinforced polyester composites and the assessment of their mechanical properties, encompassing tensile strength, flexural strength, and impact strength. Scanning Electron Microscope (SEM) analysis was employed to examine interfacial properties, internal cracks, and fractured surfaces’ internal structure. Thermal properties were evaluated using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Specifically, DSC analysis gauged the thermal characteristics of sisal/hemp composites, while TGA analysis assessed the degradation and decomposition of materials in sisal and hemp fibers, as well as in the composites. The findings revealed a decrease in composite density with increasing fiber content.