Extrusion processing for manufacture of low-density microcellular polycarbonate foams uing carbon dioxide | Posted on:2005-01-21 | Degree:M.A.Sc | Type:Thesis | University:University of Toronto (Canada) | Candidate:Lee, John W. S | Full Text:PDF | GTID:2451390011452267 | Subject:Engineering | Abstract/Summary: | | A continuous extrusion process for the manufacture of low-density microcellular polycarbonate (PC) foams using CO2 is presented. Due to its outstanding mechanical properties and high thermal resistance, polycarbonate foams have been considered as a candidate that will broaden the applications of foams in new industrial areas with high temperature environments.;This thesis presents the effective strategies for increasing the volume expansion ratio and the cell density of polycarbonate foams. The basic strategies are: (a) to use sufficiently high pressure all through the extrusion system; (b) to use branched material; (c) to use high pressure drop rate at the die exit; (d) to use sufficiently high contents of CO 2; (e) to optimize the processing temperature. The effects of processing and material parameters on foam morphologies were thoroughly studied using a single-screw tandem foam extrusion system. By tailoring the processing and material parameters, polycarbonate foams with an expansion ratio of up to 19 times with a cell density over 1010 cells/cm3 were successfully produced. | Keywords/Search Tags: | Foams, Polycarbonate, Extrusion, Processing | | Related items |
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