| Abstract: | Unmodified epoxy glass fiber laminates are brittle by nature. In this study, an improvement of the mechanical properties, such as impact, tensile and flexural strengths of the reinforced glass fiber diglycidyl ether of bisphenol-A based epoxy laminate, was carried out by incorporating an amine functional aniline formaldehyde condensate (AFAFC) modifier. AFAFC was synthesized by reacting aniline and formaldehyde in an acid medium (pH 4) and was characterized by FT-IR and 1-H NMR spectroscopy, viscosity measurements, elemental analysis and potentiometric titration. The fracture energies of the modified glass fiber composite were vastly improved and the improvement depended on the concentration of the modifier. The optimum properties were obtained by adding 10 phr (parts per hundred parts of epoxy resin) of the modifier. Furthermore, the fracture energies of the modified glass fiber composite increased with increasing the number of glass fiber layers. Scanning electron microscopy showed that round shaped AFAFC oligomer domains were formed in the matrix. These oligomer domains led to improved strength and toughness due mainly to the 'rubber toughening' effect in the brittle epoxy matrix. The thermal stability of the modified epoxy composites by thermogravimetric analysis was also reported. |
