The localization of multi-walled carbon nanotubes (MWCNTs) in PMMA/LDPE blends was studied. Theoretical predictions suggested their preferential localization in the PMMA. Conversely, experimental work revealed that non-functionalized MWCNT5 located in the LDPE, polymer first to melt. When the extrusion time is not long enough, the MWCNT5 do not have the chance to further migrate to the thermodynamically most favourable phase. The evolution of a double percolation determined if the composite became semi-conductive. In that sense, two blends with PMMA to LDPE ratios of 80:20 and 20:80 containing 2 wt.% MWCNTs had electrical resistivity values in the order of 105 and 10(12) Omega cm, respectively. Only in the 80:20 blend was the "effective" MWCNT concentration high enough such that electrical percolation was attained. However, bulk rheological properties were controlled by the major phase. Thus, 2 wt.% MWCNTs had a notable effect on the linear viscoelasticity at low frequencies of the 20:80 blend. (C) 2017 Elsevier Ltd. All rights reserved.