This present study is focused on exploring the possibility of using agricultural waste in the form of cereal straw as an active filler of biocomposites. The effect of lignocellulosic filler addition on the multifunctional properties of natural rubber composites was investigated. The results were compared with the properties of vulcanizates containing commonly used reinforcements in elastomer technology (carbon black, silica, chalk, talc). Rubber mixtures filled with straw showed the highest torque increase during rheometric measurements, which indirectly indicated a high degree of crosslinking and hardness of composites. It was found that the effect of straw addition on vulcanization time of elastomer blends was comparable with the results obtained for other conventional fillers. Moreover, the results confirmed that novel composites based on natural rubber filled with crop residues were attractive materials owing to their capacity for the formation of “structure” in combination with a good impact on reinforcement. Vulcanizates with the addition of straw showed the best barrier properties and resistance to thermo-oxidative aging from all tested samples. Furthermore, straw-based composites demonstrated that cereal straw waste could be used as an alternative, biodegradable and eco-friendly reinforcement of natural rubber composites.

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This research paper aims to provide an examinations on biocomposites based on natural rubber (NR), natural straw fibers as well as their production techniques and properties. After pre-alkalization of the fillers, two main modification methods were carried out, with the usage of acetic or maleic anhydride to improve the adhesion of the fibers to the elastomeric matrix. Firstly, physicochemical characterization of straw particles, both pure and modified, using scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and Fourier transmission infrared spectroscopy (FTIR) was performed. Moreover full characterization of the produced composites was also executed, which included: rheogical properties, static and dynamic mechanical properties, crosslinking density, damping properties, tear strength and resistance to simulated aging processes. Increased adhesion between modified straw fibers and the elastomeric matrix was observed for 10 phr filled composites, which was confirmed by dynamic mechanical thermal analysis (DMTA). In addition, the impact of the applied modifications was confirmed by higher values of the Payne effect, which resulted from the presence of developed secondary structure of the filler in vulcanizates. Furthermore, the crosslinking density of composites increased, which was reflected in the improvement of tensile properties, determined by tensile and tear strength and relative damping.