Preparation and characterization of deproteinized natural rubber/graphene oxide composite

This study aims to prepare and characterize a composite of graphene oxide (GO) and deproteinized natural rubber (DPNR/GO). The GO was synthesized using the modified Hummer method, and characterized with XRD, Raman, TEM, and water contact angle measurements. The results showed that GO was succesfully exfoliated from graphite with XRD diffraction peak shifted from 11 degrees to 26 degrees, the Raman D/G band intensity increased from 0.11 to 0.93 and the water contact angle increased from 67 degrees to 85 degrees. Then, DPNR/GO composite was prepared via graft copolymerization using tetraethylenepentaamine/tert-butyl hydroperoxide (TEPA/TBHPO) as redox initiators and the composites with GO content of 0.5, 1.0, and 1.5 phr were studied. The XRD pattern for DPNR/GO showed no significant difference to that for DPNR. However, there is a slightly shift in IR absorption peaks at 3461 and 1747 cm-1 for DPNR/GO composite compared to DPNR/GO blend. The Tg of DPNR at -65.2 degrees C was also shifted to -64.1 degrees C after formation of DPNR/GO composite. The DPNR/GO composite with 1.0 phr of GO exhibited the highest gel content (60.9%) and tensile strength (9.74 MPa) among the samples. While the storage modulus of DPNR/GO composite (0.99 MPa) was lower than that of DPNR/GO blend (3.31 MPa), DPNR/GO composite exhibited both energetic and entropic elasticity compared to the blend.