Thermally crosslinked rigid…rod aramids, 1. Synthesis of a new monomer and its polymerization

✍ Scribed by Christoph Rickert; Peter Neuenschwander; Ulrich W. Suter

• Book ID: 102939081
• Publisher: John Wiley and Sons
• Year: 1994
• Tongue: English
• Weight: 695 KB
• Volume: 195
• Category: Article
• ISSN: 1022-1352
• DOI: 10.1002/macp.1994.021950210

✦ Synopsis

Abstract

With 2,2,6,6‐tetraoxo‐1,3,5,7‐tetrahydro‐2,6‐dithia‐s‐indacene‐4,8‐diamine (DSDA) (8), a new monomer for the synthesis of thermally crosslinkable rigid‐rod aramids was developed. DSDA was copolymerized with p‐phenylenediamine and terephthaloyl dichloride by a low‐temperature solution polycondensation to give high‐molecular‐weight aramids (inherent viscosity η~inh~ > 2,2 dL/g). The fraction of DSDA could be varied from 0 to 100 mol‐% of the diamine used in the condensation. All polymers showed a weight loss due to thermal elimination of SO~2~. Thermal crosslinking could be effected by curing the samples at high temperatures (280–320°C). The crosslinking reaction was investigated by means of thermogravimetry (TG), thermogravimetry/mass spectrometry (TG‐MS), Fourier transform infrared (FT‐IR), ^13^C cross polarization‐magic angle spinning nuclear magnetic resonance (^13^C CP‐MAS NMR) and electron paramagnetic resonance (EPR). The activation energy for this reaction was found to be between 150 and 170 kJ/mol. Curing of the polymer samples led to the generation of stable, matrix‐isolated radicals.