Journal article
The effects of polymer melt rheology on the replication of surface microstructures in isothermal moulding
Series of isothermal compression moulding experiments were performed with a polycarbonate and a polystyrene melt in a hot press. The bottom plate in the hot press was equipped with a microstructured nickel insert. The insert contained 10 parallel, rectangularly shaped microchannels with a depth of 9.4 micrometer, a width of 22 micrometer and a distance between the channels of 18 micrometer.
The channels were positioned parallel to the incoming molten plastic flow. The polymer melt was frozen just before the flow-front of the melt reached the end of the inserts. The partly replicated microstructures were examined using a confocal laser scanning microscope. With increasing Deborah number, defined as De = G'/G'', there is a considerable decrease in the (non-dimensional) length the flow front has to move in order to fill the microchannels.
Numerical flow calculations were performed using the Lagrangian Integral Method where the fluid is described by a molecular stress function (MSF) constitutive model. The numerical modelling of the flow was performed on two length scales, at a macro-level describing the flow between the mould plates and at a micro-level describing the flow into the structure.
The information from the macro-level was passed to the micro-level as an applied local boundary condition.
Language: | English |
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Year: | 2005 |
Pages: | 191-200 |
ISSN: | 18732631 and 03770257 |
Types: | Journal article |
DOI: | 10.1016/j.jnnfm.2005.03.007 |
ORCIDs: | Rasmussen, Henrik Koblitz |