PhD thesis defence Sunkeun Kim

Nanoparticles find extensive applications in various industries and scientific fields to enhance material performance. Among these nanoparticles, silica is a standard filler system for passenger car tire treads, significantly improving properties such as fuel consumption, safety, and durability compared to conventional carbon black fillers. However, surface modification with functional chemical groups, like in-situ silane, is essential for silica fillers, leading to drawbacks such as complex mixing processes and the generation of harmful by-products during production. An alternative, promising approach is pre-treatment, eliminating the need for silane agents and enhancing silica efficiency in tire applications.

This PhD thesis explores the impact of different treatment techniques, namely plasma modification and molecular layer deposition, on silica surface properties and compound performance when it applied into NR/silica or SSBR/silica model compounds, representing both truck/bus and passenger car tire tread applications. Results show that plasma-treated silica improves properties in silane-free compounds but is insufficient to replace the current silane/silica combination. The research indicates that ongoing investigation is necessary to address the identified drawbacks of plasma modification. On the other hand, It is demonstrated that MLD-treated silica enhances processability and achieves desired compound properties in truck/bus tire tread applications. Additionally, it exhibits the potential to improve mechanical properties in SSBR compounds for passenger car tire applications. Combining these findings, It concludes that MLD-modified silica shows promise for use in both truck/bus and passenger car tire tread applications, offering an alternative to the current silica/silane system with significant improvements in terms of ethanol generation and mixing conditions.