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Thermoforming conditions in transparent/opaque coextruded sheet
Author(s) -
Progelhof Richard C.,
Throne James L.
Publication year - 1974
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.760141114
Subject(s) - thermoforming , opacity , materials science , radiant heating , delamination (geology) , radiant energy , composite material , absorption (acoustics) , layer (electronics) , optics , radiation , paleontology , physics , subduction , biology , tectonics
Processors have encountered processing problems in dealing with thermoforming co‐extruded sheet where one layer is semitransparent to incident radiant energy of the heater banks and the other is opaque. An analysis of the radiant heating process shows that significant volumetric absorption of radiant energy takes place within the semitransparent sheet. From the model, it is shown that to minimize temperature excursions within laminated sheets (and thus reduce the tendency for delamination and blistering), heater banks should be programmed to cycle in an on‐off mode with a rather short cycle period.