| The dissertation consists with two parts. First, study on the optical properties of transparent epoxy/clay nanocomposites; second, study on the preparation and relationship between micro-structure and mechanical properties of epoxy/rubber/clay composites.Study on the optical properties of transparent epoxy/clay nanocompositesA new type transparent epoxy based nanocomposites has been prepared by the reaction of alkylammonium exchanged montmorillonite (AMT) with diglycidyl ether of bisphenol A (DGEBA) and triethylamine as the curing agent. The morphology of AMT in the epoxy matrix was characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The effect of the AMT morphology on the optical transparency of epoxy/AMT composites (Ep/AMT) was also investigated. The light transmittance of exfoliated and intercalated nanocomposites was made a comparison. Results showed, the transmittance of the former was notably higher than that of the latter with the same AMT content. The light transmittance of the former with small AMT content was higher than that of the latter with relatively higher AMT content at the shorter wavelengths, and was lower than the latter at the longer wavelengths. And normalized light transmittance increased when the wavelength increased and the AMT content decreased, whenever the AMT is exfoliated or intercalated. On the additional, the light transmittance of composites prepared with different amounts of curing agent was also investigated. The results suggested that, the insufficient curing agent was benefited for the exfoliation of AMT. The corresponding composites were more transparent than that prepared with stoichiometric and surfeit curing agent. The results was explained with the scattering theory of spherical particles, which indicated that the effect of morphology of composites on the transparency mainly came from the exfoliation extent of AMT, which caused the change of the particle size and basal spacing of AMT in epoxy matrix, and the effect of the particle size was more significant than the basal spacing of AMT.Furthermore, the coefficient of thermal expansion (CTE) of exfoliated nanocomposites has been studied. When the AMT concentration was below 3phr (3g AMT/100g epoxy resin), the CTE values of composites decreased from 0 to 20 % of that of pure epoxy, however, the light transmittancies in near IR region of composites were more than 80% of that of the pristine epoxy, indicating that epoxy/AMT exfoliated nanocomposites could be used as packaging materials for optoelectronic devices.Study on the preparation and relationship between micro-structure and mechanical properties of epoxy/rubber/clay compositesEpoxy/rubber/clay composite has been prepared by the melted intercalation of octadyl ammonium exchanged montmorillonite (C18) with DGEBA and carboxyl-terminated butadiene-acrylonitrile random copolymers (CTBN), and piperidine as the curing agent. The effect of experimental conditions on the micro-structure and mechanical properties of composites has been studied in details, such as the addition of CTBN, the concentration of C18, the mixing procedure, curing process and so on. Results showed that, clay was only dispersed in the epoxy phase and had not any effect on the phase separation of epoxy and CTBN. With the increase of clay concentration, the impact strength of composites decreased significantly while the bending modulus increased. However, the mixing procedure and curing process had no direct influence on the mechanical properties. On the additional, clay would be exfoliated and dispersed very well when it was mixed with epoxy and CTBN simultaneously, two-step curing process and small amounts clay was used.The ERC composite was also prepared via solution mixing with clay pre-treated by onium ions having epoxy and hydroxyl groups. The structure and mechanical properties of the composites prepared via different preparation process was investigated. Results demonstrated that the reaction between onium i...
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