The application and use of environmentally friendly components in rubber compound formulation is one of the most challenging goals of the tire industry. Specifically, tires are composed of elastomeric materials, obtained through the vulcanization of one or more polymers in the presence of curing agents and many other components, such as inorganic fillers, stabilizers, oils and resins. In particular, resins play a crucial role for the improvement of the rheological behaviour of the elastomeric compound, as well as the mechanical properties of the final product, such as rolling resistance and wet traction. However a significant issue of standard resins used for tire production is their fossil hydrocarbon source and the related environmental impact. Because of this, there is a strong interest in the development of more sustainable and renewable resins which fulfil specific requirements without altering the applicative properties of the final product. In order to achieve this goal, it is fundamental to investigate what happens at the molecular level between polymer and resin and to relate it with the macroscopic behaviour and performances of the final material [1]. In this context, we characterized both cured and uncured styrene-butadiene based compounds, containing three different resins, one of which of vegetal origin, by means of low-field time-domain and high-resolution solid-state NMR (SSNMR) techniques, which proved to be key to study resin/polymer interactions and miscibility, as well as the effect of resins on the overall dynamics of polymer chains. In particular, 1H time-domain experiments allowed us to measure 1H spin-lattice relaxation times in the laboratory (T1) and in the rotating frame (T1?), as well as 1H spin-spin relaxation times (T2), which are sensitive to molecular and mobility differences in heterogeneous materials, as they depend on the modulation of 1H-1H dipolar couplings by molecular motions. Moreover, 1H T1 and T1? relaxation times measured at different temperatures allowed us to investigate the effect of resin on polymer chain dynamics. Complementary structural information on each ingredient of the compounds were obtained by 13C high-resolution SSNMR [2,3,4]. The results obtained by combining time-domain and high-resolution techniques provided useful information regarding both polymer-resin interactions and mixing degree, gaining insights into the structure-property relationship, which is helpful for the design of rubber compounds and the rationalization of their macroscopic behaviour. References [1] B. Rodgers, W. Waddell, Chapter 9-The Science of Rubber Compounding. In The Science and Technology of Rubber, 4th ed., 417-471 (2013) [2] K. Saalwachter, Rubber Chemistry and Technology, 85, 350-386 (2012) [3] K. Mu?ller, and M. Geppi Solid State NMR: Principles, Methods, and Applications, (2021) [4] M. Pierigé, F. Nerli, F. Nardelli, L. Calucci, M. Cettolin, L. Giannini, M. Geppi, and F. Martini Appl. Sci. 13, 1939 (2023)
A SOLID-STATE NMR INVESTIGATION OF THE INFLUENCE OF RESINS ON THE STRUCTURE AND DYNAMICS OF SBR ELASTOMERIC COMPOUNDS
F Nardelli;L Calucci;
2023
Abstract
The application and use of environmentally friendly components in rubber compound formulation is one of the most challenging goals of the tire industry. Specifically, tires are composed of elastomeric materials, obtained through the vulcanization of one or more polymers in the presence of curing agents and many other components, such as inorganic fillers, stabilizers, oils and resins. In particular, resins play a crucial role for the improvement of the rheological behaviour of the elastomeric compound, as well as the mechanical properties of the final product, such as rolling resistance and wet traction. However a significant issue of standard resins used for tire production is their fossil hydrocarbon source and the related environmental impact. Because of this, there is a strong interest in the development of more sustainable and renewable resins which fulfil specific requirements without altering the applicative properties of the final product. In order to achieve this goal, it is fundamental to investigate what happens at the molecular level between polymer and resin and to relate it with the macroscopic behaviour and performances of the final material [1]. In this context, we characterized both cured and uncured styrene-butadiene based compounds, containing three different resins, one of which of vegetal origin, by means of low-field time-domain and high-resolution solid-state NMR (SSNMR) techniques, which proved to be key to study resin/polymer interactions and miscibility, as well as the effect of resins on the overall dynamics of polymer chains. In particular, 1H time-domain experiments allowed us to measure 1H spin-lattice relaxation times in the laboratory (T1) and in the rotating frame (T1?), as well as 1H spin-spin relaxation times (T2), which are sensitive to molecular and mobility differences in heterogeneous materials, as they depend on the modulation of 1H-1H dipolar couplings by molecular motions. Moreover, 1H T1 and T1? relaxation times measured at different temperatures allowed us to investigate the effect of resin on polymer chain dynamics. Complementary structural information on each ingredient of the compounds were obtained by 13C high-resolution SSNMR [2,3,4]. The results obtained by combining time-domain and high-resolution techniques provided useful information regarding both polymer-resin interactions and mixing degree, gaining insights into the structure-property relationship, which is helpful for the design of rubber compounds and the rationalization of their macroscopic behaviour. References [1] B. Rodgers, W. Waddell, Chapter 9-The Science of Rubber Compounding. In The Science and Technology of Rubber, 4th ed., 417-471 (2013) [2] K. Saalwachter, Rubber Chemistry and Technology, 85, 350-386 (2012) [3] K. Mu?ller, and M. Geppi Solid State NMR: Principles, Methods, and Applications, (2021) [4] M. Pierigé, F. Nerli, F. Nardelli, L. Calucci, M. Cettolin, L. Giannini, M. Geppi, and F. Martini Appl. Sci. 13, 1939 (2023)I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
