MECHANICAL PROPERTIES AND DEFORMATION BEHAVIOR OF A CARBON NANOFIBER POLYMER COMPOSITE MATERIAL

摘要

Tensile behavior of a carbon nanofiber reinforced vinyl ester polymer composite was studied using dog-bone shaped specimens to obtain its mechanical properties. Pyrograf HI which is a very fine, highly graphitic and yet low cost carbon nanofiber was used as the fiber material. Vinyl ester with low molecular weight which was used as the matrix material is a thermoset with high tensile strength at room temperature. When small amounts of carbon nanofibers are combined with vinyl ester, the stiffness of the resulting composite can improve if the fiber-matrix adhesion is good. The mechanical properties can improve further after surface treatment (functionalization) of carbon nanofibers. This surface treatment adds some functional groups chemically to the nanofiber's surface which increases the adhesion between nanofiber and matrix resin. Understanding the mechanical behavior of these composites is crucial to their effective application. In this research the stiffness, strength, and tensile deformation behavior of these nanocomposites were investigated. The effects of matrix curing systems and composition, strain rate, nanofiber concentration, nanofiber surface treatment and environment such as low and high temperatures and humidity were also characterized. Based on the mechanical properties simple models were used to represent tensile stress-strain and deformation behaviors of the nanocomposite. The experimental results were also applied to these models to examine their predictive capability.