Abstract
Impact of nanosized oxide particles of titania (rutile) (TiO2) and silica-titania fumed compound on physical properties related to inner structure of a styrene-cross-linked polyester resin have been experimentally studied. The IR-spectroscopy and the positron annihilation lifetime spectroscopy (PAL) were used to study the electronic polarizability of interatomic bonds and the positron annihilation processes with increasing the filler loading. All the nanocomposites show unmonotonous variations in the IR-absorption lines and the positron annihilation parameters. Three lifetime components, namely τ1, τ2, and τ3 with intensities I1, I2, and I3 have been determined. The lifetime loading dependences exhibit non-monotonous lowering within the low loading range (Cm ≤ 5%) with the minima values at Cm ~ 1.5 % for the unfilled resin and the nanocomposites. The free-volume portion fv (in %) in a polymer matrix decreases droningly for the nanocomposites with STO-particles upon loading while for the TiO2-nanocomposites it increases non-monotonously. The parameters describing the supramolecular structure of the nanocomposites have been calculated using the fractal approach. Some correlations between loading-dependent PAL-properties and underlying alterations in the resin's supramolecular structure have been discussed.
Highlights
In recent years, nanosized oxides such as SiO2 [1−6], TiO2 [7−10], and silica-titania (STO) fumed compound [10] are being intensively employed as fillers to improve electric, mechanic, or thermal properties of various polymers
The unsaturated polyester resin (UPR) used in the present work is a typical example of a good-performing network polymer
A promising feature of oxide-filled polyester nanocomposites (PNCs) is a possibility of tailoring their parameters by varying filler’s loading, particle’s size, dielectric permittivity, and number of active surface sites [12−16] because these are the factors which influence on particle-polymer interactions [17]
Summary
In recent years, nanosized oxides such as SiO2 [1−6], TiO2 [7−10], and silica-titania (STO) fumed compound [10] are being intensively employed as fillers to improve electric, mechanic, or thermal properties of various polymers. Thermosetting polymers with a three-dimensional network structure are more useful in practical applications than thermoplastics because they are harder, more chemically inert and have better mechanical strength and heat resistance due to the high degree of crosslinking between polymeric chains [11]. The unsaturated polyester resin (UPR) used in the present work is a typical example of a good-performing network polymer. A promising feature of oxide-filled polyester nanocomposites (PNCs) is a possibility of tailoring their parameters by varying filler’s loading, particle’s size, dielectric permittivity, and number of active surface sites [12−16] because these are the factors which influence on particle-polymer interactions [17]. The question of how to optimize tailoring the physical properties of PNCs for specific/customer needs by varying the above-mentioned filler's parameters still remains one of the most important challenges for applied polymer sciences
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