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Kinematics, dynamics and stability of the tubular film extrusion of various polyethylenes
Author(s) -
Kanai Toshitaka,
White James L.
Publication year - 1984
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.760241508
Subject(s) - low density polyethylene , materials science , linear low density polyethylene , polyethylene , high density polyethylene , extrusion , composite material , crystallization , isothermal process , instability , blow molding , thermodynamics , mechanics , physics , mold
A basic study of the kinematics, dynamics, and heat transfer occuring during tubular film extrusion of polyethylene is outlined. Three rheologically characterized polyethylenes, a low‐density polyethylene (LDPE), a linear‐low‐density polyethylene (L‐LDPE), and a high‐density polyethylene (HDPE) were used in this study. The kinematics and stability of the tubular film process were investigated over a wide range of blow‐up ratios, drawdown ratios, and frost‐line heights. Local deformation rates along the bubble have been determined. Regions of stability and instability are described. Tensions and inflation pressures have been measured and expressed in terms of locol elongational viscosities. Temperature profiles along the bubble were determined and interpreted in terms of local heat transfer coefficients. Positions of crystallization and temperature profiles have been noted and used to estimate rates of crystallization. The characteristics of the LDPE, LLDPE, and HDPE are contrasted.