| Summary: | 碩士 === 國立臺灣大學 === 材料科學與工程學研究所 === 96 === This research focuses on the fabrication and the characterization of carbon nanotubes-liquid crystalline epoxy resin nanocomposites for strong and lightweight aerospace structural applications. The carbon nanotubes (CNTs) are first acid washed and then functionalized with epoxy resins. Functionalized CNTs are characterized by Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy and Transmission Electron Microscopy (TEM) and are found to help disrupt the strong van der Waals force between the nanotubes and prevents them from bundling together for homogeneous dispersion in the polymer matrix.
Several kinetic models are employed to study the curing behaviors of the nanocomposites. From the kinetic study, we find that the reaction rate increases and the activation energy decreases with increasing concentrations of carbon nanotubes and this arises from the high thermal conductivity of the carbon nanotubes.
Differential scanning calorimetry (DSC), thermomechanical analysis (TMA), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA) and microhardness tests are applied to characterize the cured nanocomposite materials. The material properties are enhanced by the carbon nanotubes. 2.00 wt% CNT increases the glass transition temperature by 33.4°C, the decomposition temperature by 13.8°C, storage modulus by 15.27%, peak temperature of the tan δ by 64.6°C and the microhardness by 63.3%. The improvements of thermal and mechanical properties of carbon nanotube reinforced liquid crystalline epoxy resin nanocomposites may be explained by the aligned and branched structures observed in optical and electronic microscopy study.
Higher CNT concentrations do not further improve the material’s properties because the accelerating effect of CNTs also antedates the vitrification and turns the reaction to diffusion control driven. As the molecular motions are limited, the degree of cure is lower than expected and the samples would require longer curing time.
|
|---|
