The interplay between the fragility and mechanical properties of styrene–butadiene rubber composites with unmodified and modified sago seed shell powder

Reinforcing rubber with natural fillers from agrarian wastes is a new area of interest in developing rubber composite technologies. Lignocellulosic material from sago seed shell is one of the important promising natural fillers having 37% cellulose used to reinforce styrene–butadiene rubber (SBR) for enhancing its mechanical properties. Moreover, chemically or physically modified natural fillers play a significant role in enhancing the properties of SBR like morphological, thermal, and electrical characteristics. In this investigation, the changes encountered in molecular mobility, glassy dynamics, thermal stability, flexibility, and tensile strength of SBR on reinforcing with unmodified and modified sago seed shell powder were studied using broadband dielectric spectroscopy (BDS) in conjunction with thermogravimetric analysis, and mechanical properties. BDS has been successfully employed to investigate the relaxation phenomena and glass/rubbery transition in SBR, as well as its composites with unmodified and modified sago seed shell powder over the frequency (10^?1 to 10⁷ Hz) and wide temperature range (?100 to 150°C). Experimental data were analyzed in terms of electric modulus formalism and were suited well with the Havriliak Nigami equation. The incorporation of filler and its nature (unmodified or modified it with polyaniline, PANI) greatly influenced the morphological pattern, miscibility, and mode of interaction with the rubber matrix of SBR, which owed a path to diverse charge transport mechanism in the composites. The mechanical properties of all the composites were in good correlation with the steepness index obtained from BDS. The tensile strength, tear strength, and hardness of SBR increased slightly on loading with unmodified cellulose, whereas with modified cellulose causes substantial enhancement in its tensile strength.