International audienceHumic substances (HS) perform a fundamental role in aquatic environments, exhibiting different levels of reactivity in retaining metal ions and organic pollutants. Also, they control the primary production of these ecosystems and act in the carbon sequestering process. In order to improve our understanding vis-à-vis the structural and functional features of HS from aquatic systems, this study aimed to chemically and spectroscopically characterize humic acids (HA) isolated from bottom sediment samples of a stream in a Brazilian subtropical microbasin by elemental analysis, and infrared (FT-IR), ultraviolet and visible (UV-Vis) and solid-state 13C nuclear magnetic resonance (CP-MAS 13C NMR) spectroscopies, thermogravimetry (TG), and scanning electron microscopy (SEM). Although all samples originated from the same environment, the data showed that the HA have distinct chemical and spectroscopic properties, and that the location and characteristics of the sampling points from which the sediments were collected played an important role in the differences observed. Furthermore, vascular plant matter is probably the main contributor to these samples

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The aim of this work was to use additives from renewable sources to develop an elastomeric formulation with reduced environmental impact and lower rolling resistance. Twelve compositions containing various proportions of rice husk ash—RHA (20, 40, 60, 80, and 100 phr to replace carbon black [CB]) and a combination of RHA with CB (30CB/10RHA and 20CB/20RHA) using cashew nut oil (3 phr) as a processing aid were prepared and characterized based upon their rheometric and physical–mechanical properties. The combined use of CB and RHA after the silanization process (30CB/10RHAS) increased wet grip by 3.6%, reduced rolling resistance by 17.3%, and improved abrasion resistance by 7.3%. Therefore, the use of these alternative raw materials represents an important contribution for the technological development of rubber compounds, with a combination of durability, safety, economy, and reduction in CO2 emissions. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 48314.