Please login first
Natural and Petroleum-Based Resins: Impact on SBR Dynamics by Solid-State NMR Spectroscopy and Relaxometry
1, 2 , 1, 2, 3 , 2, 3 , 4 , 5 , 1, 2, 3 , * 1, 2, 3
1  Department of Chemistry and Industrial Chemistry, University of Pisa, Pisa 56124, Italy
2  Institute of Chemistry of Organometallic Compounds, National Research Council (ICCOM-CNR), Pisa 56124, Italy
3  Center for the Integration of Scientific Instrumentation of the University of Pisa (CISUP), Pisa 56126, Italy
4  Pirelli Tyre S.p.A., Milan 20126, Italy
5  Institute of Physics of São Carlos, University of São Paulo, São Carlos 13566-590, SP-Brazil
Academic Editor: Fahmi Zairi

Abstract:

In the tire industry, tackifying resins are essential ingredients because they modulate green tack and green strength of the uncured rubbers, facilitating their manipulation and preventing creep and tear of the final products. From a molecular perspective, the presence of the resin alters the dynamics of the polymer chain, resulting in the modification of the rheological and viscoelastic behaviour of the rubber compounds. Since the mechanical response of the final compounds varies depending on the type of resin added, it is important to dissect the molecular origins of such differences. In this research, we compared the effect of a natural- and a petroleum-origin resins on the dynamics of Styrene-Butadiene Rubber (SBR) in compounds of interest for the tyre industry. To this end, we employed a variety of Solid-State Nuclear Magnetic Resonance experiments (SS-NMR) at variable temperature. These include 1H Field Cycling NMR, DIPolar chemical SHIFT correlation and Centerband Only Detection of Exchange experiments. These techniques enabled the study of polymer dynamics on a wide range of motion time scales, form the fast segmental motions related to glass transition to the slower and collective motions of the polymer chains. In addition, measurements of 1H T1 and T relaxation times provided information on the polymer-resin miscibility on the nanometer scale, which is essential for achieving compounds with the desired mechanical properties. Dipolar-Filtered Magic Sandwich Echo experiments were also carried out to obtain information on the presence of domains with different degree of mobility, as well as on the onset of their motions with temperature. The SS-NMR results were compared with those from dynamic-mechanical, rheometric, calorimetric and chemical characterization. This approach provided valuable information to elucidate the complex relationship between molecular and macroscopic properties in rubber compounds, aiding the design of formulations with improved performances.

Keywords: Natural Resins; SS-NMR; Elastomers; FFC Relaxometry; Dynamics

 
 
Top