Polyhydrazides. IV. Preparation and properties of poly-N-ethyl- and isopropylhydrazide oxadiazoles

✍ Scribed by Iwakura, Yoshio ;Uno, Keikichi ;Kurosawa, Shigeru

• Publisher: Wiley (John Wiley & Sons)
• Year: 1970
• Tongue: English
• Weight: 609 KB
• Volume: 8
• Category: Article
• ISSN: 0449-296X
• DOI: 10.1002/pol.1970.150080911

✦ Synopsis

Abstract

High molecular weight poly‐N‐alkylhydrazide‐oxadiazoles have been prepared in poly‐phosphoric acid by alkylation of poly‐1,3,4‐oxadiazole which was synthesized from terephthalic acid and hydrazine sulfate. Various kinds of reagents having an alkoxy group were used as alkylating agent, and N‐ethylated and N‐propylated polyhydrazides containing oxadiazole units were obtained. The thermal properties of the polymers obtained were investigated by using infrared spectroscopy, viscometry, differential thermometric and thermogravimetric techniques. Soluble poly‐N‐alkylhydrazide‐oxadiazole are thermally cyclized to poly‐1,3,4‐oxadiazole with elimination of olefins and water at 226–330°C for propylated polydrazide and at 240–360°C for ethylated polyhydrazide. For both, weight loss in polyhydrazides occurs in two distinct stages corresponding, respectively, to cyclization and decomposition of the poly‐1,3,4‐oxadiazole formed in situ.