Cereal straw and their physical modifications with hydrophilic and hydrophobic silica – The influence of functional hybrid material on natural rubber biocomposites

[Display omitted] •Production of hybrid fillers with pure and silanized cereal straw or two types of silica.•Creating materials with significant economic and environmental benefits.•Development of natural rubber biocomposites containing hybrid fillers. Unmodified and silanized cereal straw and two types of silica (hydrophilic and hydrophobic) were chosen to produce functional hybrid fillers. The method of mechanical grinding with simultaneous mixing was used to combine the applied compounds. The obtained materials were subjected to thermal, morphological and dispersive analysis as well as surface wettability. The introduction of an inorganic phase into the lignocellulosic material improved the thermal stability of the systems. A new functional additive with significantly lower polarity was obtained by combining hydrophobic silica and silanized straw. The prepared organic-inorganic hybrid materials were used as fillers of natural rubber (NR). The determined processing and usage properties indicate the beneficial effect of newly formed additives on the parameters of crosslinking, rheometry characteristics and aging resistance. In addition, organic-inorganic hybrid additives are capable of producing a more developed filler structure in the elastomer matrix, which results in an increase in crosslinking density and mechanical strength of the vulcanizates. The presence of the straw-silica hybrid system has a significant influence on the barrier properties and flammability of the NR vulcanizates.