Polypropylene (PP) blend-based nanocomposites were prepared using two PPs, namely, PP30 and PP90, which have different flow properties. A low density polyethylene (LDPE) was mixed with PP in the blend-based composites, and an organo-montmorillonite (15A) was used as a nano-filler. 15A was dispersed more finely in the high-viscosity PP30-based matrix, due to a more efficient intensive mixing, than in the low-viscosity PP90-based matrix. The nanocomposites were achieved with the presence of a maleated polyolefin (EPMA) compatibilizer. 15A retarded the crystallization of both PPs in the (nano)composites. The crystallization onset temperature of PP dropped by 9.4 degrees C and 8.4 degrees C, respectively, in the PP30- and PP90-based nanocomposites at 40 degrees C min(-1) cooling rate. The melting temperature of the two PPs increased in the nanocomposites, wherein PP30 exhibited a slightly higher degree of increase than PP90. The PP30-based nanocomposite exhibited a higher degree of enhancement in thermal stability than the PP90-based nanocomposite. The degradation temperature of PP at 10% weight loss raised by 39.1 degrees C and 30.4 degrees C, respectively, for PP30- and PP90-based nanocomposites in air. The presence of EPMA caused a significant increase (more than 10 folds) in the impact strength of the nanocomposites compared to neat PPs. (C) 2013 Elsevier B.V. All rights reserved.