Abstract
Linear and branched polyethylene resins are extensively used in film production for packaging. Branched polyethylenes, such as low density polyethylene (LDPE), are unique due to their high melt strength and good optical properties; while linear polyethylenes, such as linear low density polyethylene (LLDPE), exhibit excellent physical properties and drawdown capabilities The combination of both resins via blends or coextrusion provides a mix of film properties very difficult to achieve with pure materials. This paper evaluates the performance of thick blown films made from blends of LLDPE (1.0 melt index, 0.926 density) with high pressure LDPE (0.2 melt index, 0.920 density), versus three-layer coextruded films made of the same materials at the same resin ratios. A major market for these films is in pack aging free-flowing granular products. The objective is to answer which fabrication method yields superior mechanical properties, as well as outline the fundamental reasoning to understand the differences through structural and morphological analyses
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