Compatibilization effect of TiO2 nanoparticles on the phase structure of PET/PP/TiO2 nanocomposites

Abstract

AbstractPolyethylene terephthalate (PET)/Polypropylene (PP)/TiO2 nanocomposites were prepared by compounding a PP/TiO2 nanocomposite premix with PET in absence and presence (up to 6 vol %) of maleic anhydride grafted polypropylene (PP‐g‐MA). In absence of PP‐g‐MA, the TiO2 nanoparticles were mainly located at the PET/PP interface and to a lesser extent in the dispersed PET droplets. As the TiO2 nanoparticles were coated by polyalcohol their surface could react with PP‐g‐MA and thus improving the compatibilization with PP. Therefore in presence of PP‐g‐MA the TiO2 nanoparticles were preferentially located in the PP. The incorporated TiO2 nanoparticles exerted a compatibilization effect on the PET/PP blend. Depending on the location of TiO2 three different compatibilization mechanisms were proposed to be at work: (1) Locating at the interface, the TiO2 nanoparticles decrease the free energy of mixing, and thus increase the thermodynamic stability of the nanocomposites; (2) The TiO2 nanoparticles at the interface also prevent the coalescence of PET droplets; (3) Preferentially located in the PP matrix, the TiO2 nanoparticles decreased the viscosity ratio which facilitated the droplet breakup of PET. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1616–1624, 2009