فهرست نشریات علمی دسترسی آزاد ایران

In this work, epoxy-based nanocomposites were fabricated using chitosan-modified silica (CS), and polyhedral oligomeric silsesquioxanes (POSS) as reinforcements. The effects of nanoparticle type and weight fraction (wt.%) on the mechanical, thermal, and morphological properties, as well as the curing process, were investigated. Results indicated that the surface functionalization of silica with chitosan was pivotal in optimizing the nanocomposite performance, leading to a marked enhancement in tensile strength, thermal resistance, and ash content. In the formulation containing 1 wt.% POSS, incorporation of 1 wt.% unmodified silica resulted in a Young’s modulus of 417 MPa. In contrast, substitution with chitosan-functionalized silica significantly enhanced the modulus to 717 MPa. Moreover, the char yield of the samples containing POSS and unmodified silica was 9.48%, while the use of chitosan-modified silica at the same loading level increased the char yield to 11.73%. Investigation of the curing behavior revealed that both the heating rate and the nanoparticle content significantly influenced the curing process, and all samples exhibited acceptable curing performance according to the curing index. Additionally, a progressive increase in POSS concentration resulted in greater surface hydrophobicity of the nanocomposites. Furthermore, the incorporation of chitosan-modified silica led to enhanced fracture toughness and improved nanoparticle dispersion throughout the epoxy matrix. These findings suggest that the synergistic effect of chitosan functionalization and the systematic tuning of CS and POSS concentrations can effectively optimize the performance of epoxy-based systems. This characteristic may reduce susceptibility to microbial and bacterial contamination, highlighting the suitability of these materials for biomedical applications.