An improved method for measuring the thermal coefficient of linear expansion of flexible polymer films

✍ Scribed by Churl S. Kim; Thor L. Smith

• Publisher: John Wiley and Sons
• Year: 1990
• Tongue: English
• Weight: 355 KB
• Volume: 28
• Category: Article
• ISSN: 0887-6266
• DOI: 10.1002/polb.1990.090281116

✦ Synopsis

Abstract

A novel method has been developed and tested to determine accurately the linear coefficient of thermal expansion α of flexible films without subjecting a specimen to a tensile load continuously during the measurement of expansion data. Other methods have invariably required the application of a tensile load which commonly leads to creep during the experimental time. The new method involves mounting an Invar jig in the lower grip in a Dynastat. The closed‐loop servo control in the Dynastat enables the length of a specimen to be determined at a series of decreasing or increasing temperatures without subjecting the specimen to a tensile load, except momentarily on occasion while length data are being determined. Otherwise, a specimen is subjected to a small bending force. To demonstrate that the method gives valid results, α for an aluminum foil was determined and found to agree exactly with literature data. Expansion coefficients and values of the glass transition temperature (T~g~) were determined on FEP and PFA Teflon films and also on a commercially available polyimide film, Upilex‐SGA.