Improving properties of modified silica by admicellar polymerization technique for inner rubber tube products

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Thamchoto Prajaksood
Thirawudh Pongprayoon
Komkrit Pitiruek


Modified silica using admicellar polymerization technique (APT) has shown to effectively reinforce natural rubber products. The study has shown that reinforcing natural rubber with APT-modified silica at the 40 phr yields excellent mechanical and ozone aging resistant properties. For the 40 parts per hundred of rubber (phr) sample, the cure time was found to be 138.23 ± 1.06 s. The tensile strength, the 300% modulus and the tear strength were 21.55 ± 0.40 Megapascal (MPa), 4.62 ± 0.17 MPa and 73.67 ± 1.58 MPa, respectively. The elongation at break was measured to be 579.96 ± 6.70%. The hardness was 55.33 ± 1.15 shore A. These surpass the standard values for motorcycle and bicycle rubber inner tube products, according to the Thai Industrial Standard (TIS) 683-2530 and TIS 652-2529. Scanning electron microscopy studies revealed that their outstanding mechanical properties were related to the better adhesion between the silica particles and the rubber matrix, resulting from the thermal admicellar polymerization process. The minimal cracks observed after the ozone aging resistance test also suggest high durability.


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