Thermal and mechanical properties of an epoxidized natural rubber composite containing a Li/Cr Co-doped NiO-based filler

B Khumpaitool, S Utara, P Jantachum


Li and Cr co-doped NiO-based (LCNO) filler was successfully synthesized by the sol-gel process using metal nitrate compounds as starting materials and citric acid as a crosslinking agent, followed calcination at a temperature of 1000˚C for 3 h. Composites of Li and Cr co-doped NiO/epoxidized natural rubbers with 25 mol% epoxidation (abbreviated as LCNO/ENR-25) were prepared by mixing using a two-roll mill. The ENR-25 was blended with 0.5, 1, 2 and 3 phr (parts per hundred of rubber) of LCNO and the specimens were shaped at 160˚C using compression molding. The LCNO/ENR-25 composites were characterized by thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). Additionally, a tensile tester was used to measure tensile strength, elongation at break and the modulus at 100% strain of the composites. The thermogravimetric analysis showed a slight increase in the decomposition temperature of the rubber composites with the addition of LCNO. The best dispersion of LCNO filled ENR-25 was observed with an LCNO loading of 3 phr. The incorporation of LCNO into ENR-25 resulted in an increase in the tensile strength and elongation at break, but decreased the modulus at 100% strain. The LCNO/ENR-25 composite with a content of 3 phr had the highest elongation at break (711%) and the highest tensile strength (18 MPa) compared to that of the ENR-25 vulcanizates (673% and 17 MPa, respectively), probably due to the better dispersion of LCNO in ENR-25.

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