Abstract: A comparative study was performed for the molecular structures and performance of two types of special polyethylene resins designed for singlelayer cast films. Although these two resins are produced through a Unipol gas phase method and had a melt flow rate of 3.5 g/10 min, one resin is domestically made and the other one is imported from ExxonMobil. The results indicated that the relative molecular weight and its distributions of the two resins were similar to each other. Moreover, these two resins also exhibit a similarity in sequence structure and distribution of comonomer in their macromolecules. However, there are differences in the composition distributions and crystallization behavior of the two resins, which resulted in higher impact toughness and tearing resistance but poor tensile and optical properties for the domestically made resin in comparison with the imported one.

Key words: cast film, sequence distribution, crystallization, composition distribution