The Properties of Pipes Produced under the Conditions of Spiral Flow

Abstract

Abstract The present communication is concerned with the relation between the strength properties and the morphology of low-and high-density polyethylenes in the extrusion of pipes under the conditions of spiral flow. It has been found that the optimal strength properties of pipes result when lamellar crystals are oriented in the middle portion of the pipe wall about 45° relative to its axis. Model experiments have been carried out on polystyrene melts through the use of optical-polarization technique and, as a result, the data obtained for polycrystalline polymers have been verified from the qualitative point of view.