Effect of fused technique to the density and mechanical properties of the nylon 12 filled epoxy composites

In polymer composites, fillers like Nylon are often added to improve mechanical and physical properties. However, the presence of filler-filler interactions can lead to agglomeration, creating voids that weaken the composite's strength. To address this issue, a fusion technique was applied in this study to reduce void formation and improve the overall performance of Nylon-filled epoxy composites. Two types of Nylon powders, Nylon SP301 (pure Nylon) and Nylon SP305CF (Nylon with Carbon Fibers), were used in varying weight percentages (3%, 6%, 9%, 12%, and 15%). The fusion technique involved heating the cured composites at specific temperatures and times. The density results showed that Nylon SP305CF/Epoxy composites had slightly higher densities (1.15 g/cm³ to 1.12 g/cm³) than Nylon SP301/Epoxy composites (1.14 g/cm³ to 1.11 g/cm³) due to the presence of carbon fibers. At 195°C, the density of SP305CF composites decreased more, as the carbon fibers interfered with the fusion of Nylon particles, causing voids. A larger density reduction occurred at 205°C. The mechanical properties showed that the elastic modulus and stress of Nylon SP301 composites increased after fusion, with stress relaxation fluctuating depending on filler loading. SP305CF composites, while inconsistent due to carbon fibers, generally exhibited higher elastic modulus and stress than SP301 composites. The DSC analysis indicated that at 195°C, the glass transition temperature (Tg) of both Nylon and epoxy increased with fusion time, especially in SP301 composites, reflecting increased stiffness. In SP305CF composites, the presence of carbon fibers caused fluctuations in Tg. At 205°C, the Tg values of Nylon and epoxy in SP301 composites converged, suggesting better material compatibility with longer fusion time. A fusion temperature of 205°C for 20 minutes was selected for further study as it provided more complete fusion, especially at higher filler loadings, compared to 195°C where incomplete fusion and residue were observed. The 15% filler loading was identified as optimal for achieving the best fusion results.