Barrier Properties Enhancement By Adding Modified Graphene Oxide in Poly(3-hydroxybutyrate) Membranes

Poly(3-hydroxybutyrate) (PHB) is a kind of biosynthetic polyester and it has been considered as a packaging material due to its good biodegradability and good mechanical properties. The barrier and physical properties of modified graphene oxide/poly(3-hydroxybutyrate) (mGO/PHB) composite membranes were investigated in this study. In order to enhance the dispersibility and compatibility of graphene oxide (GO) in organic solvents and PHB, toluene-2, 4-diisocynate (TDI) was used to modify the hydroxyl or the carboxylic groups on the surface of GO. The suspension test showed that the dispersion of modified GO (mGO) was much better than that of unmodified GO in chloroform and PHB/chloroform solution. Uniform and well-dispersed composite membranes of mGO/PHB could be successfully obtained by the solution casting method. It was found that the crystallization temperature (T_c) of the composite shifted to higher temperature, indicating that mGO was a nucleating agent for the polymer matrix. The thermal stability and the mechanical properties of the composite membranes increased with the content of mGO. Most importantly, the oxygen and water vapor permeability of mGO/PHB membranes were reduced to half and two-thirds, respectively, of that of the pristine PHB membrane just by adding 1.0 wt% mGO. The addition of small amount of mGO could largely improve the barrier properties of PHB membranes.