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Solid state coextrusion: A new technique for ultradrawing thermoplastics illustrated with high density polyethylene
Author(s) -
Griswold Phillip D.,
Zachariades Anagnostis E.,
Porte Roger S.
Publication year - 1978
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.760181106
Subject(s) - high density polyethylene , materials science , extrusion , composite material , polyethylene , polymer , ultimate tensile strength , die (integrated circuit) , lubricant , wafer , modulus , conical surface , nanotechnology
Abstract Ultraoriented films of high density polyethylene (HDPE) have been prepared in continuous lengths by a new method, solid state coextrusion, through conical dies of extrusion draw ratios up to 36. Preformed HDPE billets ∽7 cm long and ∽1 cm in diameter of duPont Alathon 7050R, M w = 59,000, M n = 19,900, were split longitudinally into halves and then one or more wafers of the same polymer were inserted between the two sheath halves. Thereafter, the whole assembly was extruded through a conical die of 20° included entrance angle in the absence of lubricant and at temperatures substantially below the melting range yielding continuous and transparent films. The physical and mechanical properties of the HDPE films so produced were evaluated and compared with the properties of the same polymer extruded through a slit die. The high melt transition, tensile modulus and transparency confirm the effectiveness of the new method in continuously attaining ultradrawn films.