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Exploring the Impact of Nanosilica Surface Modification and Polyphenolic Antioxidants on the Mechanical Properties of NR/SBR Blends

Alinoori, Amir | 2024

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 57277 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Pircheraghi, Gholamreza
  7. Abstract:
  8. Sustainable development is a crucial objective in contemporary human societies, particularly in the production of polymer materials. One of the key pillars in achieving this goal is the preservation of the environment through the use of eco-friendly additives in polymer production, especially elastomers. The aging of rubbers (elastomers) due to environmental factors such as heat, oxygen, ozone, and UV light is inevitable. However, antioxidants are employed to delay this aging process and extend the performance life of rubber compounds. In this study, extracts from green sources like green tea and grape seeds were evaluated for their antioxidant properties using the DPPH Assay and EC50 factor. The results indicated that red grape seed extract (EC50 = 15.42 µg/ml) and white grape seed extract (EC50 = 36.08 µg/ml) exhibited higher antioxidant properties compared to green tea extract (EC50 = 70.79 µg/ml), attributed to their higher polyphenolic content and purity. Nanosilica, a significant green reinforcement in nanocomposites, is extensively used in the rubber industry. However, the dispersion of these nanoparticles in non-polar polymer matrices is hindered by the presence of silanol groups on the silica surface, leading to agglomeration. This research compared two types of nanosilica—recycled and fresh. To enhance the surface properties of these nanoparticles, some samples were treated with silane coupling agent 69, while others were grafted with polyphenolic compounds from the extracts. The modification of nanosilica surfaces improved the dispersion and distribution of nanoparticles within the rubber matrix, as confirmed by SEM images. This enhancement led to improved mechanical properties, including tensile and tear strength. Additionally, grafting the extracts onto the nanosilica surface prevented the migration of these natural antioxidants, thereby better preserving the mechanical properties after thermal-oxidative aging (for 3 and 6 days at 100°C) and reducing crack initiation and propagation after ozone aging (for 10 hours at 50 pphm concentration) compared to the commercial antioxidant TMQ in NR/SBR rubber mixtures. Thus, the antioxidant and antiozonant properties of the extracts were validated in the rubber matrix
  9. Keywords:
  10. Sustainable Development ; Aging ; Mechanical Properties ; Rubber Compound ; Nanosilica Surface Modification ; Green Tea Extract ; Grape Seed Extract ; Eco-Friendly Additives ; Natural Rubber and Styrene Butadiene Rubber (NR/SBR)Nanocomposite

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