Glass-Transition Temperature (Tg) of Free-Radically Prepared Polyacrylonitrile by Inverse Gas Chromatography, 2. Molecular-Weight Dependence of Tg of Two Different Types of Aqueous Polymers

✍ Scribed by Masatomo Minagawa; Hiroyasu Kanoh; Satoshi Tanno; Masaru Satoh

• Publisher: John Wiley and Sons
• Year: 2002
• Tongue: English
• Weight: 121 KB
• Volume: 203
• Category: Article
• ISSN: 1022-1352
• DOI: 10.1002/macp.200290027

✦ Synopsis

Abstract

The molecular‐weight dependence of the glass‐transition temperature (T~g~) of a series of atactic polyacrylonitriles (PAN)s was studied by inverse gas chromatographic (IGC) analysis. PANs having different molecular weights were prepared by either; (i) the addition of isopropyl alcohol as a chain‐transfer agent, or (ii) a scission reaction induced by the addition of alkali (NaOH) to a solution (N,N‐dimethylformamide solution, at 25 °C) of the resulting polymer. The intrinsic viscosity [η] was in the range of 10.9–0.1 (dl · g^−1^), which corresponds to a viscosity‐averaged molecular weight (M~v~) of 1 590 000–3 000. As part of the results, a side reaction, which saw the conversion of the nitrile (CN) groups of PAN into amide (CONH~2~) and/or carboxylic acids (COOH) groups by alkali, was found to occur. The typical molecular‐weight dependence of the T~g~ in free‐radically prepared PAN was discussed in connection with a chain‐transfer mechanism in an aqueous medium.

Molecular‐weight dependence of the T~g~ for PAN (WA). An error bar is given by a short vertical arrow.

magnified imageMolecular‐weight dependence of the T~g~ for PAN (WA). An error bar is given by a short vertical arrow.