ABSTRACT
A new type of siloxane core modified phthalide cardo chain based polyimide (PI) was successfully prepared from siloxane core dianhydride and ether linked phenolphthalein diamine moiety. This PI was further modified with different weight percentages of multi-walled carbon nanotubes (MWCNTs) to obtain MWCNT reinforced PI nanocomposites. The enhancement in the glass transition temperature and improved thermal stability could be afforded by the restrained motion of polymeric chain, caused from nanoreinforcement effect of MWCNTs. The successive increment in the concentration of MWCNTs resulted in augmented dielectric constant because of interfacial polarization of MWCNTs. This PI shows better solubility and low water uptake percentage of 0.42-0.58%. The morphological studies ascertain the molecular level dispersion of MWCNT throughout the PI matrix.
ABSTRACT
A series of skeletal modified novel allyl terminal benzoxazines (BZ-als) have been successfully designed and developed using triaryl pyridine core diamines via conventional one-pot Mannich reaction. The polybenzoxazine-silica (PBZ-SiO2) nanocomposites were prepared by thermal ring-opening polymerization of benzoxazines with different weight percentages of 3-methacryloxypropyltrimethoxysilane through in-situ sol-gel method. The formation of hybrid nanocomposites was confirmed by FT-IR. The substantial enhancement in the glass transition temperature was remarked for PBZ-SiO2 hybrids than their respective neat PBZ systems. The dielectric constant of the nanocomposites was found decreased with an increment in the silica content. The shift in the characteristic absorption/emissions corresponding to the neat PBZs toward lower wave-length ascertains the successful formation of PBZ-SiO2 nanocomposites. The discernible phase behaviour observed morphological studies reveals the molecular-level dispersion of silica particles over the organic networks.
