Anionic polymerization of caprolactam—XXXIX. Number of polymer molecules formed per molecule of acyl caprolactam in high-temperature polymerization

✍ Scribed by J. Šebenda; V. Kouřil

• Publisher: Elsevier Science
• Year: 1971
• Tongue: English
• Weight: 600 KB
• Volume: 7
• Category: Article
• ISSN: 0014-3057
• DOI: 10.1016/0014-3057(71)90067-x

✦ Synopsis

At temperatures around 200 ~, condensation and cleavage reactions occur with polymerization, leading to a change in the number of macromolecules. The final number of polymer molecules (A r) depends on the balance between these reactions, their relative rates being affected, in particular, by the concentration of sodium caprolactam (c,). For short reaction times (5-20 rain), the number of macromolecules is in most cases lower than the starting concentration of acyl caprolactam (c,); the ratio N/c, approaches unity only at low c, values, whert the condensation reactions are unimportant. With increasing concentration of sodium caprolactam, the importance of condensation increases; branched molecules are found containing, besides amine and carboxy groups, more than one acyl group from acyl caprolactam. At the same time, condensation reactions consume most of the strong bases. At c, > 0"02 m-mole/g, reactions become important by which the number of polymer molecules formed per molecule of acyl caprolactam may rise; with increasing c, the ratio N/c, again approaches unity. At 210" for t = 5-20 rain and e, < 0"017, N/c, = I -32c,; for cs > 0'017: N/c, = 0-46 + 4"2 (c, = 0-017). With increasing reaction time, N/ca increases owing to the cleavage reactions. The number of polymer molecules depends rather on the concentration of sodium caprolactam than on the ratio c,/c,.