The influence of temperature on the plastic deformation of polyethylene

Abstract

AbstractTemperature influences the attainable draw ratio, the transparency of the drawn material, the long period and the intensity distribution in the small angle X‐ray diffraction pattern. Drawing at or below 80°C yields a first order small angle maximum with relatively large lateral width indicating a variation of lamellar surface orientation between 90° and 45° to the draw direction. Drawing above 80°C reduces the lateral width of the first order maximum and leads to the appearance of the second order. The thermal history of the starting material, quenched, slowly cooled, or annealed, affects the draw behavior. The long period, however, seems to be independent of the physical conditions of the initial sample. At 60°C, for instance, the drawing of polyethylene samples with a long period of 195, 250, 290, 310, and 380 Å yields a material with long periods between 170 and 180 Å.Annealing drawn samples produces observable changes even at 90°C. At temperatures below 120°C annealing for 100 min yields long periods slightly below those for samples drawn at the same temperature. At 120°C and above the drawing and annealing show nearly the same long period. Annealing also greatly increases the intensity of the X‐ray small angle reflections, but at temperatures below 120°C causes only minor changes in the lateral width of the same reflections.