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Depolymerization of poly‐ϵ‐caprolactam catalyzed by sodium hydroxide
Author(s) -
Mukherjee A. K.,
Goel D. K.
Publication year - 1978
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1978.070220205
Subject(s) - depolymerization , caprolactam , sodium hydroxide , yield (engineering) , polymerization , monomer , catalysis , chemistry , alkali metal , sodium , acetone , materials science , nuclear chemistry , polymer chemistry , organic chemistry , polymer , composite material
Depolymerization of poly‐ϵ‐caprolactam chips was carried out at low pressures (3–15 mm Hg) and elevated temperature (225°–270°C) in the presence of sodium hydroxide as catalyst. The effects of variation of amount of sodium hydroxide, time, temperature, and pressure on ϵ‐caprolactam yield were studied. With increase in alkali content the yield increases linearly, reaching a maximum at 1% (w/w) NaOH and then falls. The yield increases with time of depolymerization up to 4 1/2 hr and then becomes practically constant. Between 240° and 250°C there is a sudden increase in depolymerization rate. Further increase in temperature has very little effect. Decrease in pressure from 15 to 3 mm Hg shows a nine‐fold increase in yield. The optimum conditions for the depolymerization were a temperature of 250°C, a pressure of 3 mm Hg, and a time 4 1/2 hr in the presence of 1% NaOH (w/w), which gave a 90.5% yield of ϵ‐caprolactam. Physical properties, IR spectra, and behavior toward polymerization of the recovered monomer indicated the presence of some impurities.