Abstract
Carbon nanotubes (CNTs) provide a high potential for the modification of glass-fiber reinforced polymer (GFRP) composite laminates. This paper reports CNTs/GFRP composite laminates were fabricated by using ultrasonication and the hand layup method. This study was aimed at investigating the interlaminar shear strength (ILSS) and flexural strength of composites consisting of adding several different proportions of CNTs. When CNTs content is 0.75 phr (per hundred resin), the mechanical properties are the best. The ILSS and flexural strength were significantly improved by 15.7% and 9.2%, respectively.The effects of CNTs addition on the mechanical performances were evaluated with respect to retention of high-temperature properties up to 200 °C. It was found that ILSS, flexural strength, bending modulus and fatigue properties were significantly enhanced by CNTs at different evaluated temperatures. Fiber-matrix interfacial strength significant weakening and matrix softening was a major factor affecting the strength and modulus reduction observed at high temperature. The storage modulus, measured by dynamic mechanical analysis (DMA), showed temperature dependence nearly identical to the ILSS, flexural strength and bending modulus for GFRP and CNTs/GFRP composite laminates. The experimental results were examined to understand the fracture surface observed by scanning electron microscope (SEM).In addition, because the matrix is polymer-based and its mechanical properties are influenced by both temperature and time, it is important to consider its viscoelastic behavior. This was accomplished by conducting the time-temperature superposition principle (TTSP) experiments using DMA. From the TTSP results, master curves were constructed for the storage (E’) and the loss moduli (E”) as a function of frequency at pre-selected reference temperature. The long-term storage modulus, loss modulus, tanδ and relaxation modulus of GFRP was predicted based on TTSP.