We made comparison of titanium dioxide powders obtained from three syntheses including sol-gel and precipitation methods as well as using layered (tetramethyl)ammonium titanate as a source of TiO2. The obtained precursors were subjected to step annealing at elevated temperatures to transform into rutile form. The transformation was determined by Raman measurements in each case. The resulting products were characterised using Raman spectroscopy and dynamic light scattering. The main goal of the studies performed was to compare the temperature of the transformation in three titania precursors obtained by different methods of soft chemistry routes and to evaluate dielectric properties of rutile products by means of broadband dielectric spectroscopy. Different factors affecting the electrical properties of calcinated products were discussed. It was found that sol-gel synthesis provided rutile form after annealing at 850°C with the smallest particles size about 20 nm, the highest value of dielectric permittivity equal to 63.7, and loss tangent equal to 0.051 at MHz frequencies. The other powders transformed to rutile at higher temperature, that is, 900°C, exhibit lower value of dielectric permittivity and had a higher value of particles size. The correlation between the anatase-rutile transformation temperature and the size of annealed particles was proposed.

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The aim of this work was to study the activity of several hydrotalcite/unsaturated acid systems in the peroxide crosslinking of ethylene-propylene copolymer (EPM). Allylmalonic, citronellic, crotonic, itaconic, sorbic and undecylenic acids, as well as monoallyl maleate, were applied to ensure the activity of hydrotalcite in the peroxide vulcanization of EPM. In this article, we discuss the effect of the obtained coagents with respect to their particle size and tendency to agglomerate, as well as the effect of the applied type of unsaturated acid on the vulcanization kinetics of rubber compounds. The influence of hydrotalcite/unsaturated acid systems on the crosslink density, the mechanical properties of the vulcanizates and their stress relaxation tendency under external deformation were also studied. Hydrotalcite/unsaturated acid systems seem to be active as coagents in the crosslinking of EPM with peroxide. The type of unsaturated acid considerably influences the activity of hydrotalcite toward the ethylene-propylene copolymer. The application of such coagents increases the crosslink density of the vulcanizates and improves their mechanical properties.

Ciecze jonowe w postaci soli benzyloimidazoliowych, alkilopirydyniowych, alkilopirolidyniowych i alkilopiperydyniowych zastosowano jako substancje zwiêkszaj¹ce stopieñ zdyspergowania nanocz¹stek aktywatora wulkanizacji (tlenku cynku) i nape³niacza (krzemionki) w elastomerze butadienowo-styrenowym (SBR). W celu zmniejszenia zawartooeci tlenku cynku w wyrobach gumowych, zamiast tradycyjnego mikrometrycznego ZnO, zastosowano cz¹stki tlenku cynku o wymiarach nanometrycznych. Dodatek do mieszanek kauczukowych cieczy jonowych pozwoli³ na otrzymanie jednorodnej dyspersji nanocz¹stek w SBR. Dziêki temu uzyskano skrócenie czasu i obni¿enie temperatury wulkanizacji oraz zwiêkszenie gêstooeci usieciowania, stabilnooeci termicznej i odpornooeci na starzenie pod wp³ywem promieniowania UV wytworzonych wulkanizatów. Wulkanizaty te charakteryzowa³y siê o 60 % mniejsz¹ zawartooeci¹ tlenku cynku ni¿ próbki referencyjne.