The effects of the surface properties of several silica nanoparticles (NPs) on the dispersion and isothermal crystallization kinetics of poly(3-hydroxybutyrate) (PHB) nanocomposites were investigated by the techniques of transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and X-ray diffraction (XRD). Bare and PEGylated sol-gel silica NPs were synthesized and commercially available hydrophobic and hydrophilic fumed silica NPs were used to prepare the PHB/silica nanocomposites containing <= 5 wt% silica. Among these 4 types, PEGylated silica NPs were best dispersed in PHB matrix as evidenced by TEM images. Values of the Avrami exponent, n = 2.2 +/- 0.2 for all the PHB/silica nanocomposites, indicated that the mechanism of the crystallization of PHB was not altered by the introduction of various silica NPs. However, the crystallization rate of PHB in the nanocomposites was significantly decreased by the introduction of PEGylated silica because the rearrangement of the PHB polymer chains during crystallization was limited by the interaction and chain entanglement between PHB and the grafted PEG on silica. (C) 2017 Elsevier B.V. All rights reserved.