A new poly(butylene succinate) (PBS)-grafted vapor grown carbon fiber (VGCF)/poly(L-lactide) (PLLA) nanocomposites were successfully prepared by an in situ condensation reaction between PBS (M-w = 6,000) and surface oxidized VGCF, followed by direct melt mixing technique, and their mechanical and thermal properties were evaluated. Fourier transform infrared spectroscopy and scanning electron microscopy studies indicate a chemical interaction between the PBS and the surface of VGCF. It was found that the maximum tensile strength and modulus of PBS-grafted VGCF/PLLA nanocomposites were 135 MPa (27% increase relative to neat PLLA) and 4,400 MPa (29% increase relative to neat PLLA), respectively. The results indicate that significant improvement in the mechanical properties can be accomplished by optimizing the surface modification conditions for VGCF. (c) 2008 Wiley Periodicals, Inc.