Material properties affecting extrusion foaming

Document Type

Syllabus

Publication Date

1-1-2004

Abstract

Extrusion foaming for the production of medium-and low-density thermoplastic foams has been carried out successfully for some time with physical blowing agents (PBAs). PBAs are atmospheric gases, volatile hydrocarbons, or hydrochlorofluorocarbons (HCFCs) that are metered and dissolved in the polymer melt during processing. The extrusion foaming process can use a single extruder or two extruders operating in tandem. The basic steps in the process involve (a) melting of the solid polymer; (b) injection and dissolution of the blowing agent into the polymer melt, which is a diffusion controlled process; (c) cooling of the blowing agent laden melt; (d) expansion through the nucleation (often in the presence of nucleating agents) and growth of bubbles due to super-saturation and diffusion of gas into the nucleated bubbles (this is, generally, achieved by suddenly releasing the system pressure); and (e) stabilization of the resultant cellular structure, which is accomplished by subsequent cooling and solidification of the cell walls.

Identifier

84885154465 (Scopus)

ISBN

[9780849317286, 9780203506141]

Publication Title

Polymeric Foams Mechanisms and Materials

First Page

111

Last Page

138

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