Deformation of high-density polyethylene produced by rolling with side constraints. I. Orientation behavior

A new method of rolling with side constraints was applied to polyethylene. The process relies on the rolling of a material inside a channel formed on the circumference of one roll with another roll having a thickness matching the width of the channel in the first roll. The rolling inside a channel resembles to a large extent the plane-strain compression in a channel die. The deformation processes of linear polyethylene by compression in a channel die and by rolling with side constraints proceed in very similar fashions and produce similarly strong single-component crystal textures accompanied by chevronlike lamellar structures at comparable strains. The macromolecular chains are highly oriented along the rolling direction. At high rolling rates, {310} twinning takes place with both the channel die and rolling with side constraints because of tensile stress across the bar caused by strain recovery on unloading. The constraint rolling allows for the production of bars or profiles with relatively large cross sections (>1 cm(2)) in a continuous manner. (C) 2002 Wiley Periodicals, Inc.