Design of a Zn Single-Site Curing Activator for a More Sustainable Sulfur Cross-Link Formation in Rubber.

ZnO is a worldwide used activator for a rubber vulcanization process, which promotes fast curing kinetics and high cross-linking densities of rubber nanocomposites (NCs). However, its extended use together with leaching phenomena occurring during the production and life cycle of rubber products, especially tires, entails potential environmental risks, as ecotoxicity toward aquatic organisms. Pushed by this issue, a novel activator was developed, which introduces highly dispersed and active zinc species in the vulcanization process, reducing the amount of employed ZnO and keeping high the curing efficiency.

Glassy and Polymer Dynamics of Elastomers by H-Field-Cycling NMR Relaxometry: Effects of Fillers.

H spin-lattice relaxation rate () dispersions were acquired by field-cycling (FC) NMR relaxometry between 0.01 and 35 MHz over a wide temperature range on polyisoprene rubber (IR), either unfilled or filled with different amounts of carbon black, silica, or a combination of both, and sulfur cured. By exploiting the frequency-temperature superposition principle and constructing master curves for the total FC NMR susceptibility, χ″(ω) = ω(ω), the correlation times for glassy dynamics, τ, were determined.

Glassy and Polymer Dynamics of Elastomers by H Field-Cycling NMR Relaxometry: Effects of Cross-Linking.

H spin lattice relaxation rate ( ) dispersions were acquired by field-cycling (FC) NMR relaxometry between 0.01 and 35 MHz over a wide temperature range on polyisoprene (IR), polybutadiene (BR), and poly(styrene--butadiene) (SBR) rubbers, obtained by vulcanization under different conditions, and on the corresponding uncured elastomers. By exploiting the frequency-temperature superposition principle, χ″(ωτ) master curves were constructed by shifting the total FC NMR susceptibility, χ″(ω) = ω (ω), curves along the frequency axis by the correlation times for glassy dynamics, τ.