The objective of this study was to manufacture and investigate a novel microfibrillar-reinforced material based on fibrillized blends of polyethyleneterephthalate (PET), polypropylene (PP), and TiO2 nanoparticles (300 nm and 15 nm in size). The uncompatibilized and compatibilized blends (polypropylene grafted maleic anhydride as compatibilizer) were extruded and subsequently cold-drawn into strands with a draw ratio of 10. The effects of compatibilizer and TiO2 particles on the structure and properties of drawn strands were investigated. Upon addition of compatibilizer, the preferential location of TiO2 particles shifted from the PET-dispersed phase to the PP matrix, which brought about different structures of the drawn strands. Differential scanning calorimetry Study provided indications for a heterogeneous nucleation effect of the PET fibrils on the PP matrix and of the TiO2 particles on the PET fibrils. Dynamic mechanical analysis demonstrated that the mechanical properties of the drawn strands are strongly dependent on the strand structures. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 113: 1471-1479, 2009