Tribology and Materials | Volume 5 | Issue 1 | 2026 | 12-21
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https://doi.org/10.46793/tribomat.2026.003
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The effect of adding silica on the physical, mechanical and wear properties of rubber-based composites
Zahraa Kadhum Rodhan
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Israa Adnan Najem,
Alaa Shaker Obaida
Babylon Technical Institute, Al-Furat Al-Awsat Technical University, Hillah, Iraq
Abstract: In this study, the influence of inorganic silica addition on the physical, mechanical and tribological (abrasion resistance) properties of a natural rubber compound used in bridge expansion joints was investigated. These joints are subjected to cyclic mechanical strains and harsh service conditions, such as friction induced by movement, pressure, solar radiation and humidity, which accelerate material deterioration and increase maintenance and replacement costs. Natural rubber-based composites were prepared with silica contents of 10, 20, 30 and 50 parts per hundred rubber (phr) to mitigate these adverse effects. The aim of this work was to identify an optimal formulation that reduces permanent deformation, enhances fatigue performance, improves swelling resistance and optimises tribological behaviour. The vulcanisation characteristics (optimum cure time, scorch time and maximum torque), Mooney viscosity, specific gravity, water and oil swelling, microstructure, international rubber hardness degree (IRHD), fatigue life, compression set and abrasion resistance were evaluated. The results showed that increasing silica content reduced vulcanisation and scorch time while increasing maximum torque, Mooney viscosity and specific gravity, indicating the formation of a stiffer rubber network. Compared with the unfilled compound, silica-filled formulations exhibited higher hardness, improved fatigue resistance, lower compression set and reduced oil swelling. Abrasion resistance testing revealed a slight increase in wear with increasing silica content, which was attributed to the presence of rigid silica agglomerates. However, this effect was compensated by the overall improvement in mechanical stability and resistance to aggressive service environments.
Keywords: natural rubber, rubber-based composites, silica, mechanical properties, abrasion resistance, fatigue behaviour.
Received: 24-09-2025, Revised: 06-12-2025, Accepted: 23-12-2025
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) license, which allows users to distribute, remix, adapt,
and build upon the material in any medium or format for non-commercial purposes only, and only so long as attribution is given to the creator.
Abstract: In this study, the influence of inorganic silica addition on the physical, mechanical and tribological (abrasion resistance) properties of a natural rubber compound used in bridge expansion joints was investigated. These joints are subjected to cyclic mechanical strains and harsh service conditions, such as friction induced by movement, pressure, solar radiation and humidity, which accelerate material deterioration and increase maintenance and replacement costs. Natural rubber-based composites were prepared with silica contents of 10, 20, 30 and 50 parts per hundred rubber (phr) to mitigate these adverse effects. The aim of this work was to identify an optimal formulation that reduces permanent deformation, enhances fatigue performance, improves swelling resistance and optimises tribological behaviour. The vulcanisation characteristics (optimum cure time, scorch time and maximum torque), Mooney viscosity, specific gravity, water and oil swelling, microstructure, international rubber hardness degree (IRHD), fatigue life, compression set and abrasion resistance were evaluated. The results showed that increasing silica content reduced vulcanisation and scorch time while increasing maximum torque, Mooney viscosity and specific gravity, indicating the formation of a stiffer rubber network. Compared with the unfilled compound, silica-filled formulations exhibited higher hardness, improved fatigue resistance, lower compression set and reduced oil swelling. Abrasion resistance testing revealed a slight increase in wear with increasing silica content, which was attributed to the presence of rigid silica agglomerates. However, this effect was compensated by the overall improvement in mechanical stability and resistance to aggressive service environments.
Keywords: natural rubber, rubber-based composites, silica, mechanical properties, abrasion resistance, fatigue behaviour.
Received: 24-09-2025, Revised: 06-12-2025, Accepted: 23-12-2025
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This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) license, which allows users to distribute, remix, adapt, and build upon the material in any medium or format for non-commercial purposes only, and only so long as attribution is given to the creator.