Multiwalled carbon nanotubes (CNTs) filled polymer composite based on polycarbonate (PC) and polyethylene (PE) was fabricated by shear controlled orientation in injection molding (dynamic samples) and conventional injection molding (static samples). The morphological observation by scanning electronic microscope (SEM) indicated that PC phase in situ generated more and finer microfibrils in the dynamic samples than in the static ones, and the CNTs predominantly localized in the PC microfibrils without obvious migration to PE matrix and also aligned along the microfibrils. With such unique morphology, the tensile properties of the dynamic samples were simultaneously considerably increased compared to their complementary samples, especially in the presence of 0.5 wt% of CNTs, which indicates both stretch alignment of CNTs and molecule orientation can bring out a significant reinforcement on PE. Furthermore, the static samples displayed double yielding points in on the stress-strain curves, and interestingly, a small quantity of CNTs in PC: fibrils strengthened this phenomenon. (c) 2006 Elsevier Ltd. All rights reserved.