Thermoplastic natural rubber (TPNR) was compounded with graphene nanoplatelets (GNP) via ultrasonication and melt blending. The effects of ultrasonication period (1-4 hours) and GNP weight fraction (0.5, 1.0, 1.5 and 2.0 wt.%) on the mechanical, thermal and conductivity properties were investigated. Results showed that the 3 hours of ultrasonic treatment on LNR/GNP gave the greatest improvement in tensile strength of 25.8% (TPNR/GNP nanocomposites) as compared to those without ultrasonication. The TPNR nanocomposites containing 1.5 wt.% GNP exhibited the highest strength (16 MPa for tensile, 14 MPa for flexural and 11 kJm-2 for impact) and modulus (556 MPa and 869 MPa for tensile and flexural, respectively). The incorporation of GNP had enhanced the thermal stability. It can be concluded that the GNP had imparted the thermally and electrically conductive nature to the TPNR blend.

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This research was carried out to investigate the addition of grafted copolymers of maleic anhydride grafted-polylactic acid (PLAg-MA) and maleic anhydride grafted-natural rubber (NR-g-MA) on the mechanical and thermal properties of polylactic acid/ liquid natural rubber (PLA/LNR) blends. Prior to blend preparation, the PLA-g-MA and NR-g-MA were the first selfsynthesized by mixing maleic anhydride (MA) and dicumyl peroxide (DCP) which acted as initiator with the PLA and natural rubber (NR), respectively. The PLA/LNR, PLA/LNR/PLA-g-MA and PLA/LNR/NR-g-MA blends were prepared via meltblending method. The loading of PLA-g-MA and NR-g-MA was varied between 5, 10 and 15%, respectively. By comparing to the control sample (neat PLA/LNR blend), the addition of PLA-g-MA with 5 and 10% led to increment in tensile strength up to 22 MPa, whereas NR-g-MA promoted a negative trend of tensile properties to the blends. Differential scanning calorimetry (DSC) and thermogravimetry analysis (TGA) results showed the enhanced thermal stability for PLA/LNR/PLA-g-MA blend. Fourier transform infrared (FTIR) analysis confirmed the chemical interaction between the PLA and NR components where the grafted copolymers were successfully grafted onto PLA backbone and bonded with NR.