Analysis of crystallization kinetics of poly(ether ether ketone)

✍ Scribed by Ming Chen; Jang-Yang Chen

• Publisher: John Wiley and Sons
• Year: 1998
• Tongue: English
• Weight: 341 KB
• Volume: 36
• Category: Article
• ISSN: 0887-6266
• DOI: 10.1002/(sici)1099-0488(199806)36:8<1335::aid-polb8>3.0.co;2-q

✦ Synopsis

An optical microscope equipped with a video photograph system was used to follow the growth of spherulites. Under nitrogen atmosphere, the growth rates at 290 and 300ЊC suggest that when the melt of PEEK has been equilibrated for 15 min at 400ЊC, the subsequent crystallization behavior was nearly independent of the prior thermal history. Linear growth rates of crystallization of PEEK have been measured in the temperature range of 260 -325ЊC for melt-pressed films and solvent cast films. Detailed kinetic analysis indicated that PEEK exhibited an unmistakable regime II r III transition at 296 { 1ЊC. The II r III transition was clearly present irrespective of the rather drastic changes in U *. It is interesting that the branching and crosslinking retarded the growth rate of PEEK, but a transition from regime II to regime III still existed. For melt-pressed films after equilibration at 400ЊC for 15 min, values of s and q suggest that U * should be taken nearer to 1500 cal /mol in the case of T ϱ Å T g 0 30 K and 2000 cal /mol in the case of T ϱ Å T g 0 51.6 K. The K g ( III ) / K g ( II ) ratio ( 1.32 ) was not as close to the predicted value of 2 as was Hoffman's ratio. For PEEK, the Thomas-Staveley constant ( a ) should be closer to 0.25 or 0.3 instead of 0.1.