From Single to Hybrid Fillers: Optical, Thermal, and Mechanical Properties of Titanium Dioxide and Titanium Dioxide‐Tungsten Trioxide/Polyvinyl Butyral Nanocomposites

ABSTRACT This work investigates the role of nanosized TiO 2 and/or WO 3 particles, dispersed together within a clear PVB matrix, in providing UV protection. Both binary (TiO 2 /PVB) and ternary (TiO 2 /WO 3 /PVB) nanocomposites were prepared at 2.5, 5.0, and 7.5 wt.%, using pristine and silanized forms, via solvent casting with high‐energy sonication. Incorporating nanoparticles improved thermal stability, with DSC showing slight T g increases at low loadings and decreases at higher loadings, likely due to interphase interactions and agglomeration. Mechanical testing revealed that the pristine ternary sample 13_WT25 exhibited the highest reinforcement, with an elastic modulus of 5.7 GPa and a nanohardness of 0.4 GPa. UV‐shielding was evaluated for films of two thicknesses (8 and 30 μm) and was mainly affected by nanoparticle dispersion and interphase packing. Silanization enhanced UV shielding only for thinner films (8 μm). Silanized nanoparticles showed superior UV‐B blocking in both binary and ternary hybrids at higher nanoparticle loadings. The highest UV‐B shield (~72%) was achieved by the ternary silanized hybrid at 7.5% wt. (TiO 2 /WO 3 _sil/PVB). Conversely, in 30 μm samples, silanization had an adverse effect, with the highest UV‐B shielding (> 95%) observed in samples with pristine nanoparticles.