On Thursday, June 25th, 2015, Ms. Karnda Sengloyluan has defended her thesis entitled 'Silica-Reinforced Natural Rubber: Use of Natural Rubber Grafted With Chemical Functionalities as Compatibilizer'.
Silica-reinforced tire tread compounds contribute greatly to a production of low rolling resistance or energy-saving rubber tires. Silica-silane coupling agent technology is practically used under optimal conditions to provide good balance of key tire performance: rolling resistance, wet grip and wear resistance. Natural rubber (NR) is a renewable resource providing excellent mechanical and dynamic properties especially low heat build-up that makes it suitable for truck tire compounds. NR-silica is naturally incompatible and silane coupling agent such as bis-(triethoxysilylpropyl)tetrasulfide (TESPT) is commonly used to bridge the two components. Alternative pathways are to modify either the silica surface or rubber molecular structure to achieve a better polarity matching and enhance the compatibility. This thesis provides an in-depth study on the application of epoxidized natural rubber (ENR) as alternative compatibilizer in the silica-reinforced NR compounds. The use of ENRs alone as compatibilizers clearly enhances the silica-NR compatibility, silica dispersion and some properties. The properties can be further enhanced by using ENR in combination with only small amounts of silane coupling agents and sulfur compensation relative to a reference compound with TESPT. Silane-grafted NR is another alternative that provides an enhancement of NR-silica compatibilization. These alternative compatibilizers to totally or partially replace the silane provide the advantages of NR-based product usage and less ethanol emission from the silanization reaction. Moreover, the use of ENR brings in a good wet grip in the perspective of the “Magic Triangle of Tire Technology”.