Properties and characterization of poly lactic acid/natural rubber/graphene nanocomposite

Abstract

Natural rubber toughened poly lactic/graphene (PLA/NR/graphene) nanocomposites were prepared by two different processes known as in-situ melt mixing process (conventional) and integration of latex compounding - melt mixing process. These two processes were employed to compare the state of graphene dispersion and distribution in the nanocomposite. The objectives of this research comprise the effect of different processing methods and graphene content on the morphology, mechanical and thermal properties of PLA/NR/graphene nanocomposite. The composition of PLA/NR blend was fixed at 80/20 wt% and the graphene content was varied at 0.1-0.4 phr. Mechanical properties were studied by tensile, flexural and impact test. The tensile and impact strength were slightly improved with increasing of graphene loading (from 0.1-0.3 phr) indicating that graphene significantly effective in increasing the mechanical properties of toughened PLA nanocomposite. The PLA/NR/graphene nanocomposite was characterized by field emission scanning electron microscopy and scanning electron microscopy. Integration of latex compounding and melt mixing process showed better graphene distribution and dispersion compared to the conventional processing method. Differential scanning calorimetry and thermogravimetric analysis were used to determine the temperature profile: glass transition temperature (Tg), melting temperature (Tm) and cold crystallization temperature (Tcc) and also to access thermal stability of the nanocomposite. The results also revealed that the PLA/NR blend was reinforced and toughened simultaneously by graphene. The simultaneous improvement in tensile strength and toughness could be attributed to the homogeneous dispersion of graphene in PLA/NR/graphene nanocomposite. The integration of latex compounding and melt mixing process had given a promising method to homogenously dispersed graphene in the polymer matrix.