Effect of the Modified Silica Nanofiller on the Mechanical Properties of Unsaturated Polyester Resins Based on Recycled Polyethylene Terephthalate

Unsaturated polyester resin (UPe)-based nanocomposites and fumed silica Aerosil R812S, R805 and R816, and R200 modified with phenyl terminal group, R200NPh, were prepared. UPe resins were synthesized from maleic anhydride and products of glycolysis, obtained by polyethylene terephthalate depolymerization with dipropylene glycol in the presence of tetrabutyl titanate catalyst. The obtained unsaturated polyesters were characterized by acid, hydroxyl, and iodine values and by FTIR and NMR analysis. The microstructural analysis of the prepared nanocomposites, performed by using transmission electron microscopy, confirmed that silica nanoparticles formed chain-like aggregates in the polymer matrix. The presence of modified silica nanoparticles had no influence on the glass transition temperature and thermal stability of polyester matrix. The tensile modulus, stress at break, and hardness of cured products increased with increasing silica content. The impact strength of cured samples was not influenced by the silica content. (C) 2015 Society of Plastics Engineers