Measurement of temperature. (a) The temperature distribution on the outer surface of the parison was measured using a thermal camera (manufactured by Nippon Avionics Co., Ltd.). (b) The temperature at 2 m or farther from the parison was measured as the ambient temperature. (c) The ambient temperature inside the parison cylinder was measured by making a cut in the direction of extrusion of the parison and using an infrared thermometer.