Preparation And Characterization Of Polymer/Silanized Kaolin Nanocomposites

This dissertation relates to biodegradable polymer-clay nanocomposites and silanized kaolin/silica core-shell nanoparticles. Most of the dissertation involves new methods to functionalize kaolin, with applications in polymer nanocomposites. A novel biodegradable nanocomposite was fabricated based on poly (3-hydroxybutyrate-co-3-hydroxyhexanoate)(PHBHHx) and silane modified kaolin/silica core-shell nanoparticles (SMKS), via solution-casting method using chloroform as solvent. Original kaolin (ORK), Glycidoxypropyltrimethoxysilane (G-silane) directly modified kaolin (SMK) and organoclay (OMMT) were also introduced into PHBHHx matrix for comparison. Additionly, series of Trans-1,4-polybutadiene (TPBD) composites based on SMKS, OMMT and Ckaolin were prepared separately. SMKS was synthesized by the sol-gel technique using tetraethyl oxysilane (TEOS) as the precursor and then treated by silane. According to transmission electron microscopy (TEM), scanning electron microscopy (SEM), electrophoretic mobility and sedimentation property, the structure and surface properties of the sol-gel modified kaolin can be controlled by varying the TEOS/kaolin mass ratio and pH. The mechanical test results showed that SMKS dramatically improved the mechanical properties of the PHBHHx compared to that of ORK, SMK and OMMT. The morphology and microstructure were observed with ultra small-angle X-ray scattering (USAXS), XRD, TEM and ESEM. Differential scanning calorimeter (DSC) and thermo gravimetric analysis (TGA) were used to investigate the thermal stability of the composites. These dramatic improvements in these mechanical properties are attributed to the fine dispersion of SMKS into the polymer and increased covalent interaction between polymer chains and the surface of SMKS.