Improvement properties of carbon fiber reinforced epoxy based composites with poss nanoparticles

High performance composites are daily used materials in marine, automotive, aerospace and defense industries. With the developing technology, their properties should be improved to fulfill the novel application's requirements. Nowadays, the nanocomposites, which are one kind of composite materials containing nanometer-sized inorganic nanoparticles, can be utilized to improve physical properties of polymers. The nanosized reinforcing materials, typically in the range of 1–100 nm, are uniformly dispersed in and fixed to a polymer matrix. Depending on the nanoscale dimension, nanosized reinforcing materials are categorized as one-dimensional (graphites and clays), two-dimensional (nanofibers, nanotubes, or whiskers) and three-dimensional (spherical silica, metal particles, polyhedral oligomeric silsesquioxanes (POSS), and semiconductor nanoclusters). Among them, the POSS nanoparticles are three-dimensional oligomeric, organosilicon compounds with cage frameworks surrounded by functional groups on the periphery. The inclusion of nanosized reinforcing materials into a polymer matrix not only dramatically improves the mechanical properties (e.g., strength, modulus, rigidity) but also reduces its flammability, heat evolution and viscosity during processing. Moreover, it brings advanced new functions in the final materials that finds applications in many industrial fields. In this thesis, mechanical properties of carbon fiber-reinforced epoxy composites were improved by addition of glycidyl-POSS as nanosized reinforcing material. The aim of this study is to improve the pyhsical properties of epoxy matrix by addition of glycidyl-POSS, which contains reactive epoxy groups. First of all, to determine the optimum POSS ratio; 1, 2, 4 and 8% glycidyl POSS was added to epoxy resin. The nanocomposites were characterized by mechanical and thermal analysis. The mechanical properties of obtained nanocomposites were investigated in accordance with the standard tests (ISO 527-2 and ISO 178). Thermal properties of the nanocomposites were also investigated by DSC and TGA analyses. The optimum improvement has been observed in the nanocomposites containing 2% glycidyl-POSS. After that, two-dimensional (0o-90o) non-crimp carbon fiber reinforcements were chosen in epoxy resin with 2% glycidyl POSS feeding ratio. The composite samples were produced by vacuum bagging method. For these samples, the mechanical properties were investigated in accordance with the standard tests (ISO 14125, ISO 14129 and ISO 14130). The strength and modulus of carbon fiber reinforced nanocomposites have been improved from 3.78 up to 20.4%. Examination of the surface morphology and interfacial debonding of the specimens was also performed via scanning electron microscopy (SEM). In conclusion, the addition of glycidyl-POSS not only enhance the interactions between carbon fiber and epoxy matrix, but also improves the mechanical properties of final composites.