A linear low density polyethylene (LLDPE) obtained from a metallocene based catalyst, was blended in an extruder with a high density polyethylene (HDPE) homopolymer synthesized with an iron based catalyst. The bimodal polyethylenes, made with blends from 0 to 100 wt % of copolymer were characterized by SEC, DSC, ESEM, SEC-FTIR, and TREF, while their resistance to the slow crack growth (SCG) was evaluated through the PENT test. Results provide that polymer blends with copolymer contents between 47.5 and 72.5 wt % are suitable for pipe applications. Furthermore, a method based on the intercrystalline tie chains calculus is proposed as suitable and attractive, because of its simplicity and novelty, to forecast long term performance and to predict capabilities. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121: 3269-3276, 2011