In situ drawing of high molecular weight poly(ethylene terephthalate) in subcritical and supercritical CO2

✍ Scribed by Terry Hobbs; Alan J. Lesser

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 255 KB
• Volume: 37
• Category: Article
• ISSN: 0887-6266
• DOI: 10.1002/(sici)1099-0488(19990801)37:15<1881::aid-polb12>3.0.co;2-v

✦ Synopsis

The effects of draw conditions were studied for initially amorphous meltspun poly(ethylene terephthalate) fibers in the presence of subcritical and supercritical (SC) CO 2 . Both in situ and posttreatment mechanical behavior along with morphological characteristics were investigated. Fibers soaked in subcritical CO 2 could be drawn to 30% higher draw ratios (DRs) compared with fibers that were cold-drawn. In situ force response measured with a custom apparatus showed that fibers in subcritical CO 2 had no measurable resistance to deformation until strain hardening occurred. In contrast, fibers drawn in SC CO 2 displayed a yield response, a significant decrease in ductility, and a significant difference in postyield behavior. Fibers drawn in subcritical CO 2 showed slightly lower tensile properties compared with cold-drawn samples whereas fibers treated in SC CO 2 had much lower tensile properties because of the limited DR achieved. X-ray diffraction studies indicated that CO 2 enhances the development of the crystalline phase compared with cold-drawn samples.