فهرست نشریات علمی دسترسی آزاد ایران

Epoxy phenol novolac resin is among the most widely used matrix materials in the fabrication of composite structures. Incorporating elastomeric droplets into the matrix is one approach to enhancing the properties of composite materials. The effects of two hydroxyl-terminated polybutadiene (HTPB) types with hydroxyl values of 0.75 and 0.45 on the impact strength, toughness, tensile properties, and dielectric characteristics of an epoxy phenol novolac resin were investigated. The results demonstrated that a 2.5 wt% addition of the first HTPB type (hydroxyl value = 0.75) led to a 15% increase in impact strength, whereas the second type (hydroxyl value = 0.45) exhibited a negligible effect. Incorporating 2.5 wt% of the first and second HTPB types improved toughness by 108% and 56%, respectively. Both HTPB variants increased elongation at break but reduced tensile strength and modulus. Additionally, the inclusion of 2.5 wt% HTPB resulted in a 70% reduction in the dielectric constant. The difference in the behavior of the two HTPB types was attributed to their varying compatibility with the epoxy phenol novolac resin. Higher hydroxyl content (0.75 vs. 0.45) improved compatibility, leading to better interfacial adhesion and more uniform dispersion within the matrix.