The polyolefin blends of high-density polyethylene (HDPE) with two types of fluorothermoplastics (THV500 and THV220); were prepared by melt compounding technique. The morphology, crystallization, and the viscoelastic measurements of the blends were carried out. The dispersion of THVs was studied by scanning electron microscopy (SEM) technique, and discussed. The crystallization characteristics of the blend were studied using Differential scanning calorimetry (DSC). The oscillatory shear measurement was employed for determining the rheological properties of the prepared blends. There is a significant difference in the rheological behavior of the HDPE blends with THV500 and THV220. The dynamic linear viscoelastic behavior (storage modulus and viscosity) of HDPE/THV500 was found to be higher than that of HDPE/THV220 blend. This was attributed to the molecular weight and particle size distribution of THVs. However, the molecular weight effect of THVs on the crystallization behavior of the blend is marginal. The master curves of the storage and loss modulus vs. frequency were constructed by applying the timetemperaturesuperposition (TTS) principle. It was established that the parsimonious and modified Cox-Merz models are fairly applicable to the storage modulus and viscosity results. (C) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013