Comparative Study of Cork Tree Bark and Silanized Cork Tree Bark as Eco-Friendly Fillers for Various Elastomers – Ecological Approach to Green Rubber Composites

This study examines elastomeric composites reinforced with native and chemically modified lignocellulosic material derived from Amur cork tree bark, focusing on the effectiveness of filler modification and its impact on composite performance. The filler was modified using n-octadecyltrimethoxysilane, and the modification was evaluated by FTIR spectroscopy, contact angle measurements, and dynamic light scattering. Successful silanization was confirmed by characteristic FTIR signals, a marked increase in hydrophobicity (water contact angle from 44.5° to 121.1°), a reduction in surface free energy to 29.03 mN/m. The influence of silanization of filler on the properties of the filled composites was evaluated based on rheometric characteristics and crosslink density, mechanical properties, surface, and barrier properties. A notable improvement in the mechanical strength of the biocomposites was observed (TSb = 19.42 MPa). A significant reduction in wettability was also recorded, particularly for XNBR-based composites, where the water contact angle increased from 33.6° to 98.5°. Furthermore, enhanced barrier properties were achieved, as evidenced by reduced liquid and gas permeability for all filled composite systems (1.6–7.3 × 10−13 mol/(Pa·m·s)). Overall, the results demonstrate proper functional properties while maintaining environmental benefits and highlight promising directions for the development of elastomeric biomaterials.