Premium
Efforts to find stick‐slip flow in the land of a die under sharkskin melt fracture conditions: polybutadiene
Author(s) -
Inn Yong Woo,
Wang Liangshi,
Shaw Montgomery T.
Publication year - 2000
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/1521-3900(200008)158:1<65::aid-masy65>3.0.co;2-h
Subject(s) - tearing , materials science , slip (aerodynamics) , polybutadiene , composite material , die (integrated circuit) , geology , extrusion moulding , breakup , mechanics , extrusion , polymer , physics , thermodynamics , copolymer , nanotechnology
Because stick‐slip or other flow disturbances inside the die land have been suggested as a possible mechanism of the sharkskin, our effort was to observe any relevant periodic changes inside the die land during the sharkskin condition. We used particle tracking and time‐resolved birefringence and two‐dimensional light scattering in conjunction with a slit die attached to an extruder and a tubular glass die attached to a pressurized reservoir. Both dies could be observed up to the exit; both could also be directly observed downstream of the exit. While periodicities were easily seen in the slip‐stick regime, none of the methods revealed any periodicity in the sharkskin regime. Direct observation of the sharkskin formation outside the die suggests a tearing and rolling mechanism as the origin of the sharkskin ridges found on polybutadiene extrudates.