Influence of nanoparticles on elastic and optical properties of a polymeric matrix: Hypersonic studies on ethylene–vinyl alcohol copolymer–titania nanocomposites

• Published in: European polymer journal 2010-03, Vol.46 (3), p.397-403
• Main Authors: Jiménez Riobóo, R.J., De Andrés, A., Kubacka, A., Fernández-García, M., Cerrada, M.L., Serrano, C.
• Format: Article
• Language: English
• Subjects: Applied sciences; Brillouin spectroscopy; Composites; Elastic properties; Exact sciences and technology; Forms of application and semi-finished materials; Nanoinclusions; Polymer composite materials; Polymer industry, paints, wood; Refractive index; Semicrystalline polymers; Technology of polymers
• ISSN: 0014-3057; 1873-1945
• DOI: 10.1016/j.eurpolymj.2009.11.009

While the inclusion of TiO 2 nanoparticles in either EVOH copolymer matrix or isotactic-polypropylene matrix induces the same elastic behaviour (a), the optical behaviour (b) presents a clear anomaly in the case of the TiO 2 inclusions in EVOH copolymer matrix (grey down triangles). High resolution Brillouin spectroscopy (HRBS) backscattering elastic data in nanocomposites of ethylene–vinyl alcohol copolymer (EVOH) and TiO 2 nanoparticles present anomalous dependence with concentration, while Young’s modulus and microhardness data show the expected behaviour. When performing HRBS with the 90A scattering geometry to asses the effective elastic constant, the expected behaviour for low concentration of TiO 2 nanoparticles is again obtained. This unusual disagreement can be solved assuming that the inclusion of TiO 2 nanoparticles induces anomalous refractive index behaviour at the applied laser wavelength for the different EVOH–TiO 2 nanocomposites. Comparison with experimental elastic and optical data obtained in isotactic-polypropylene–TiO 2 nanocomposites proves that EVOH–TiO 2 nanocomposites show an unusual optical behaviour at the laser wavelength, possibly due to a singular bonding between the EVOH polymer and the TiO 2 nanoparticles.