Study of two-phase behavior of nitrile polymers by in situ hot-stage IR spectroscopy

The temperature behavior of polyacrylonitrile with a small number of acidic groups incorporated in its chains was studied;by in situ hot-stage IR spectroscopy. It has been shown that acidic groups trigger the hydrolysis of nitrile groups at temperatures below the first glass point of polyacrylonitrile. At higher temperatures, the acidic groups separate from the hydrophobic polymer and aggregate to form clusters. This leads to the appearance of a second phase characterized by its own higher temperature glass transition at 140 degreesC. It is also shown that acidic groups do not trigger the cyclization reaction, and that their availability reduces of the reaction rate.