Novel Green Nanocomposites from Toughened Bacterial Bioplastic and Titanate Modified Layered Silicate

摘要

The new materials development is now transitioning between the petroleum based hydrocarbon chemistry and the biomass derived carbohydrate chemistry. Polyhydroxybutyrate (PHB), a bacterial bioplastic is recently highlighted because of its renewable resource based origin and potential to replace/substitute petroleum derived non-biodegradable plastic like polypropylene (PP). PHB shows susceptibility to fracture when subjected to high rates of deformation. This work investigates toughening mechanisms for PHB via incorporation of functionalized elastomeric components into the PHB matrix. A compatibilizer was investigated to improve the interfacial adhesion between the incompatible elastomer and plastic phases. Maleated polybutadiene with high grafting and low molecular weight was identified as compatibilizer. The toughened PHB was characterized through their thermo-mechanical, rheological and morphological analysis. The resulting toughened PHB showed more than 5 times improvement in impact strength over virgin PHB with around 60 % loss in modulus. The loss of modulus was recovered to the permissible extent through incorporation of titanate modified montmorillonite layered silicate. The hydrophilic clay was modified by titanate-based treatment to make it organophilic and compatible with the polymer matrix. The toughened nanocomposites were characterized by rheological, thermo-mechanical and morphological analysis and the experimental findings were co-related with Takayanagi and Halpin Tsai models.