Search

Copyright of Materialwissenschaft und Werkstoffechnik is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The investigated peel system in this study consists of a polyolefine-based, coextruded, three-layer film having ethylene-vinyl acetate (EVAc) copolymer at the interface, heat sealed against a biaxial-oriented polyethylene terephthalate film. This system can primarily be found in the packaging industry offering a residue-free and non-destructive peel behavior. The peel force required to separate the joint depends on the mass fraction of vinyl acetate (VAc) in the EVAc copolymer, the processing conditions in the blowing process of the PE/PEVAc film, and on the sealing parameters. In dependence on the processing conditions and sealing parameters, the standard peel system with EVAc copolymer containing 18 wt.% VAc was investigated. The processing parameters were varied among the processing line of the blown film and their influence on the peel properties were studied. As processing parameters the screw speed within the extruder and the resulting layer thickness, the cooling behavior of the film bubble and the blow-up ratio (BUR) of the film bubble were investigated. The effect of pretreatment conditions was also investigated. The investigations revealed a significant dependence of the peel force on the pretreatment conditions. Processing conditions and the VAc content have a minor impact on the peel properties. [ABSTRACT FROM PUBLISHER]

Recent research has shown that the resistance against crack initiation and propagation of polyethylene blown films depends on density, chain branching and crystal orientation next to the processing parameters. To assess low-density polyethylene blown film fracture toughness with different thicknesses, the essential work of fracture method has been conducted in this study. The thickness of the investigated low-density polyethylene films was regulated by the draw down ratio, which causes low-density polyethylene crystal orientation with the chain axis parallel to the machine direction at higher draw down ratios, influencing mechanical parameters and the fracture toughness. The crystal orientation was measured by X-ray diffraction. Blown films with thicknesses equal to or greater than 200 µm exhibit no preferred orientation, which is consistent with various calculated mechanical and fracture mechanics parameters. Films of less than 200 µm thickness show preferred machine direction crystal orientation and a distinct thickness influence on mechanical and fracture mechanics parameters. [ABSTRACT FROM AUTHOR]