Poly(butylene succinate) (PBS)/pristine raw multiwalled carbon nanotube (MWCNT) composites were prepared in this work via simple melt compounding. Morphological observations indicated that the MWCNTs were well dispersed in the PBS matrix. Moreover, the incorporation of MWCNTs did not affect the crystal form of PBS as measured by wide-angle X-ray diffraction. The rheology, crystallization behaviors, and thermal stabilities of PBS/MWCNT composites were studied in detail. Compared with neat PBS, the incorporation of MWCNTs into the matrix led to higher complex viscosities (|eta*|), storage modulus (G'), loss modulus (G ''), shear thinning behaviors, and lower damping factor (tan delta) at low frequency range, and shifted the PBS/MWCNT composites from liquid-like to solid-like, which affected the crystallization behaviors and thermal stabilities of PBS. The presence of a very small quantity of MWCNTs had a significant heterogeneous-nucleation effect on the crystallization of PBS, resulting in the enhancement of crystallization temperature, i.e., with the addition of 0.5 wt % MWCNTs, the values of T(c) of PBS/MWCNT composites could attain to 90 degrees C, about 6 degrees C higher than that of neat PBS, whereas the values of Tc increased slightly with further increasing the MWCNTs content. The thermogravimetric analysis illustrated that the thermal stability of PBS was improved with the addition of MWCNTs compared with that of neat PBS. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121: 59-67, 2011