Shigeji Konagaya

Dispersion of Nano TiO2 in Ethylene Glycol and Poly(ethylene terephthalate)

Nano TiO2 was dispersed in ethylene glycol (EG) by the replacement of dispersion medium from water sol. EG/TiO2 suspension was well stabilized by the electrostatic repulsive force when pH value of suspension was less than 4.3. In situ polymerization starting from bis(2-hydroxyethyl) terephthalate (BHET) and EG/TiO2 suspension was carried out to prepare a series of poly(ethylene terephthalate) (PET)/TiO2 nanocomposites. Under highly acidic conditions, 97% particles dispersed in PET matrix had the size less than 100 nm. With the increase of pH value, aggregation occurred and larger size particles appeared. A tensile test showed that Youngs modulus of PET was increased by the addition of nano TiO2

Study on Dispersion of TiO2 Particles During Polymerization of PET

An important factor influencing the stability of colloidal suspension is zeta potential (ζ-potential) on the surface of particles. In this work, ζ-potential of TiO2 particles in ethylene glycol (EG) with various additives for poly(ethyleneterephthalate) (PET) polymerization, such as metallic salts, phosphoric acid and alkyl phosphates, were investigated by electrophoretic mobility method. The dispersion stability of TiO2/EG suspension was influenced by decrease in the absolute value of the ζ-potential by the addition of metal acetates as well as phosphates. The addition of triethylamine (TEA) in the TiO2/EG suspension restrained the change of ζ-potential from negative to positive, which resulted from phosphoric acid. The molar ratio of phosphoric acid to an acetate was found to have an influence on the dispersion ability of TEA in TiO2/EG suspension. Effect of metallic salts, phosphoric acid and TEA on the stability of TiO2/EG suspension was studied in the actual polymerization of PET. It was proved that the addition of TEA is highly effective for the dispersion of TiO2 particles in PET, even in the presence of metallic salts, phosphoric acid and its alkyl phosphates.