The chain microstructure and condensed structure of polyethylene resin used for Biaxially stretched film

Abstract To explore the desirable chain structure and condensed structure of polyethylene used for biaxial stretching, the blends of two polyethylenes (PE1 and PE2) with different molecular weight and branch distribution were investigated. Their condensed structure including relaxation and crystallization behavior was studied by rheology, dynamic mechanical analysis (DMA), and non‐isothermal crystallization kinetics. And the chain microstructure was characterized by preparative temperature rising elution fractionation (P‐TREF), and successive self‐nucleation and annealing (SSA). It was demonstrated that the structural variables were not changing monotonically with the increment of the PE1 content. The longest relaxation time, lowest and less varied crystallization rate always appeared when the blend contained 15 wt% of PE1. This excellent structure was owing to the formation of more branches on the short chains, resulting in the uniform distribution of lamellae size and thus showing the widest biaxial stretchable temperature range (i.e., 8°C).