Crystallization of Poly(3-hydroxybutyrate) by Exfoliated Graphite Nanoplatelets

Poly(3-hydroxybutyrate) (PHB) has been shown to be efficiently nucleated by exfoliated graphite nanopla- telets (xGnP). The nucleating effect of xGnP was investi- gated using differential scanning calorimetry, optical mi- croscopy and atomic force microscopy. Nonisothermal crystallization of PHB from the melt required lower activa- tion energies for PHB containing 1 wt % and 3 wt % xGnP (� 214 and � 102 kJ/mol respectively) than for pure PHB (� 60 kJ/mol). A kinetic study of the PHB/xGnP crystalli- zation employing a modified form of the Avrami equation revealed that the presence of xGnP increased the PHB crys- tallization temperature, as well as the crystallization rates, and generated smaller and more numerous spherulites. Op- tical microscopy and atomic force microscopy confirmed the incorporation of xGnP into the lamellar structure of the PHB spherulites and provided insight into the influence of xGnP on spherulite size and lamellae thickness. 2007 Wiley