Effect of ammonium salts on poly(ethylene terephthalate) materials

The study of the effect of solutions of ammonium salts of low concentrations on polyester fibre material showed that modification of the material with ammonia formed by thermal hydrolysis of ammonium salts differs from modification with ammonia obtained by the reaction of equimolar quantities of ammonium nitrate and sodium hydroxide and is similar to the process that takes place when ammonia is added to the working solution. Of the salts examined, ammonium fluoride in the concentration of 0.02-0.35 M at 130°C and 30-min process time is the most active modifying agent. In these conditions, ammonium fluoride and the products of its high-temperature hydrolysis -- hydrogen fluoride and ammonia -- have the strongest catalytic effect on hydrolysis of cyclic oligomers with formation of their linear form. On the whole, ammonium fluoride has a stronger modifying effect on polyester material than aqueous ammonia.[PUBLICATION ABSTRACT]