Thermal properties and stability of Carica papaya fiber-reinforced MgO particulate epoxy composites for advanced thermal applications

Abstract

Natural fibers are increasingly being explored in the polymer industry to develop sustainable bio-composites with enhanced functional properties. While plant fibers generally suffer from thermal stability limitations, their integration with suitable fillers and resin matrices can significantly enhance their thermal performance, making them viable for engineering applications. This study investigates the fabrication and characterization of Carica papaya (CP) fiber-reinforced epoxy composites integrated with magnesium oxide (MgO) nanoparticles as fillers and epoxy resin as the matrix. Five composite laminate samples were prepared with varying MgO filler weight fractions to assess their impact on the thermal and mechanical performance of the composites. Fourier-transform infrared spectroscopy confirmed the presence of C-H stretching vibrations attributed to cellulose in CP fibers, with a crystallinity index of 59.8 %. The composites exhibited strong antibacterial properties, further enhancing their functional appeal. The incorporation of MgO fillers significantly improved both thermal and mechanical properties. Notably, the sample with 25 g of MgO filler achieved substantial enhancements, with mechanical properties improving by an average of 15.5 % and thermal properties by 25.7 %. Thermogravimetric analysis (TGA) confirmed that the thermal stability of the composites ranged between 240 °C and 410 °C, demonstrating a significant improvement over unmodified natural fiber composites. Dynamic mechanical analysis revealed enhanced viscoelastic behavior, indicating better heat resistance and dimensional stability under dynamic thermal loads. Morphological and elemental analyses showed robust interfacial bonding between CP fibers and the MgO-filled matrix, further supporting the material's structural integrity.