Mechanical Properties, Density, and Morphology Analysis of Strong and Lightweight Microfibril Cellulose Reinforced Epoxy/Micro Balloon Hybrid Composites

The study entitled "Mechanical Properties, Density, and Morphology Analysis of Strong and Lightweight Microfibril Cellulose Reinforced Epoxy/Micro Balloon Hybrid Composites" investigated the impact of microfibril cellulose (MFC) derived from Oil Palm Empty Fruit Bunch at varying concentrations (1–4 Parts per Hundred Resins, PHR) on the mechanical properties, density, and morphology of epoxy/micro balloon/MFC hybrid composites. These composites were created by mixing an epoxy matrix with low-density K-15 type micro balloons at a 70:30 volume ratio and subsequently moulding them. Mechanical properties were evaluated using a Universal Testing Machine (UTM) following ASTM D790 and D638 standards, while density was measured according to ASTM D792 guidelines. Specific strengths were calculated using standard formulas. Chemical functional groups were analysed using Fourier Transform Infrared Spectroscopy (FTIR), and filler dispersion was examined using Scanning Electron Microscopy (SEM). The results demonstrated that adding 3 PHR MFC significantly enhanced flexural strength by 90%, achieving 50.51 MPa compared to the E/MB composite. The composite containing 2 PHR MFC showed the highest tensile strength, with a 43.87% increase to 29.58 MPa. Specific flexural strength and specific tensile strength increased by 68.2% and 28.4% respectively, reaching 55.3 MPa·cm³/g and 32.6 MPa·cm³/g compared to the control composite. However, SEM analysis indicated agglomeration in the 4 PHR MFC composite, leading to reduced flexural and tensile strengths, as well as specific flexural and tensile strengths. Similarly, agglomeration in the 3 PHR MFC composite’s tensile specimens resulted in decreased tensile strength and specific tensile strength. Composites with 1–4 PHR MFC exhibited low densities of approximately 0.94 g/cm³, with the highest density observed in the 4 PHR MFC composite.