Browse Prior Art Database

Casting Thick Polymeric Sheets

IP.com Disclosure Number: IPCOM000048931D
Original Publication Date: 1982-Apr-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Lubniewski, SE: AUTHOR

Abstract

Thermoplastic sheets having high solvent content can be cast into thick void-free sheets by repeated surface "dusting" with a solvent to allow diffusion of volatile components while curing. Sheets produced in this manner provide reliable specimens for physical testing purposes.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 83% of the total text.

Page 1 of 1

Casting Thick Polymeric Sheets

Thermoplastic sheets having high solvent content can be cast into thick void- free sheets by repeated surface "dusting" with a solvent to allow diffusion of volatile components while curing. Sheets produced in this manner provide reliable specimens for physical testing purposes.

A cavitation plate 1/8" - 1/2" deep is filled with a thermoplastic resin at room temperature. The cast resin should have a high volatile content. After a skin of dry resin has formed, the skin is "dusted" with the selected solvent system by the use of an aerosol spray unit until the skin dissolves. The solvent should have a relatively low vapor pressure and evaporate at room temperature. This allows entrapped volatiles an opportunity to diffuse more rapidly.

The "dustings" with solvent are continued periodically until the majority, approximately 90 percent, of the entrapped solvents have evolved. By now the dried film volume has shrunk to a volume less than the initial pour. If a thicker film is desired, an additional dispersion material can be added and the "dustings" are repeated, as required. After adequate room temperature processing has been completed, a step-wise baking schedule may be adopted to diffuse out the majority of residual solvent remaining, without forming visible voids.

This technique can produce a nearly solid film of thermoplastic dispersion. The film made in this manner eliminates stress-raising voids during physical testing, such as ten...