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Coat hanger-type sheet die concept (A): (1) central
inlet port; (2) manifold (distributes melt); (3) island
(along with mani- fold, provides uniform pressure
drop from inlet to die lip; (4) die lip (die exit forms a
wide slit)
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Sheet die (B): (1) upper die plate; (2) lower die plate;
(3) manifold; (4) island; (5) choker bar; (6) choker bar 9
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adjustment bolt; (7) ?ex die lip; (8) ?ex lip adjustment
bolt; (9) lower lip; (10) die bolt; (11) heater cartridge.
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Coextrusion feed block manifold and sheet die (C): (1) sheet die with ?ow
restriction; (2) adapter plate; (3) feed block asembly; (4) core material layer inlet; (5)
upper material layer inlet; (6) lower material layer inlet; and
Coextrusion multimanifold sheet die (D): (1) lower melt channel; (2) upper melt
channel; (3) lower choker bar; (4) lower choker bar adjustment bolt; (5) upper choker
bar; (6) upper choker bar adjustment bolt; (7) ?ex lip.
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Die swell: When polymer exits the die of the extruder it will swell, this action is
referred to as die swell. Die swell occurs because the sudden release of pressure
causes the polymer chains to relax; and may result in actual contraction of the flow
section especially near the die region.

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