Characterization of fluoroelastomer networks: II. SEC, FTIR, and ODR analysis

✍ Scribed by A. N. Theodore; M. Zinbo; R. O. Carter III

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 782 KB
• Volume: 61
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/(sici)1097-4628(19960919)61:12<2065::aid-app3>3.0.co;2-8

✦ Synopsis

The role of an accelerator in the nucleophilic cure of fluorocarbon compounds was further examined by preparing materials without a crosslinker. Under the previously used curing conditions, ODR reveals the formation of a secondary, accelerator-induced network that is unstable a t slightly higher temperature, i.e., 2190°C. Increased crosslink density and color are observed with the cure time, indicating slow curing reactions and likely formation of conjugated unsaturation. SEC of selective solvent-soluble fractions derived from specimens obtained from the key cure stages shows initially a falling refractive-index response.

However, this change is followed by a shift in MWDs toward lower average molecular weights. On the other hand, infrared examination shows a continuous increase in the 1718 cm-' absorption, but no major presence for the 1680 cm-' absorption seen in the previous study in the presence of a crosslinker. The concurrent increase in the 3114 cm-' peak confirms the presence of a -CF = CHdouble bond. The solvent-soluble portions and bulk specimens have very similar infrared features.