Enhancing mechanical properties of polyisoprene composites through silica nanoparticle reinforcement: A comprehensive study

Elastomer composites reinforced with nanoparticles hold immense potential for advanced applications, yet their mechanical performance hinges on the interplay between filler dispersion and matrix compatibility. In this study, we systematically investigate how silica nanoparticles (SIO₂) grafted with polyisoprene (PI) enhance the elastic modulus and hardness of cis- and trans-polyisoprene matrices at varying loadings (25–65 wt.%). Through a combination of mechanical testing, microstructural analysis (TEM/SAXS), and theoretical modeling, we reveal that:

·         Cis-polyisoprene composites exhibit superior reinforcement (e.g., 65% loading: 6.51 MPa modulus, 90 Shore A hardness) due to better Sio₂ dispersion (Erg = 11.52 nm) compared to trans-matrix counterparts (Erg = 20.38 nm).

·         Matrix-free composites achieve exceptional stiffness (124.65 MPa) but sacrifice processability, highlighting a trade-off for high-loading applications.

·         Aging studies demonstrate further property enhancement (e.g., 160 HR aging boosts hardness by 25%), offering insights into post-processing optimization.

Deviations from the Guth-Gold model at high silica fractions (>45%) underscore the impact of agglomeration, prompting future strategies for improved filler-matrix design. This work provides a roadmap for tailoring elastomer nanocomposites to meet demanding mechanical and industrial requirements.