Degradation of poly(vinyl alcohol) in strongly alkaline solutions of hydrogen peroxide

✍ Scribed by A. Hebeish; Ib. Ib. Abdel-Gawad; Is. K. Basily; S. El-Bazza

• Publisher: John Wiley and Sons
• Year: 1985
• Tongue: English
• Weight: 352 KB
• Volume: 30
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/app.1985.070300605

✦ Synopsis

The action of hydrogen peroxide and sodium hydroxide independently as well as in combination together with satbilizer formulation-consisting of magnesium sulphate (5 g/L), ethylenediamine tetraacetic acid (2 g/L), gluconic acid (2 g/L), and nonionic/anionic wetting agent (1.5 g/L)--on poly(viny1 alcohol) (PVA) was investigated at 30°C and 95°C. The effect of sodium hydroxide (5-25 g/L) alone was to bring about an enhancement in the viscosity of PVA most probably due to gel formation. The latter was favored at higher sodium hydroxide concentrations and longer duration (30 min) of treatment. The opposite holds true when hydrogen peroxide (35% w/v) was used alone at concentrations ranging from 2 to 20 mL/L. The viscosity of PVA decreased as the hydrogen peroxide concentration increased. Nevertheless, hydrogen peroxide alone could not cause complete dissolution of PVA even at 95°C for 30 min. On the other hand, complete dissolution of PVA could be achieved under the influence of stabilized alkaline solutions of hydrogen peroxide at 95°C in less than 10 min. It was postulated that, under the conditions used, oxidation of PVA by hydrogen peroxide prevailed over gel formation under the influence of sodium hydroxide.