Some properties of poly‐α‐piperidone

The high molecular weight polymer of α‐piperidone, which had been unobtainable with the use of alkali metal, trialkyl aluminum, or Grignard reagent as catalyst, was prepared with M–AlEt3, (where M is alkali metal), MAlEt4 or KAlEt3 (piperidone) as catalyst and N‐acyl‐α‐piperidone as initiator. From the determination of the behavior of the solution viscosity of poly‐α‐piperidone in m‐cresol at 30°C. the value of 0.27 for the Huggins constant was obtained. Examination of the correlation between the number‐average molecular weight, determined by endgroup titration, and the intrinsic viscosity gave a somewhat small value for the endgroup COOH. This may be considered due to the consumption of N‐acyl‐α‐piperidone by a propagating polymer in the course of polymerization. The thermal stabilities of the polyamides, nylons 4, 5, and 6, was in the order nylons 6 > 5 > 4 according to differential thermal and thermogravimetric analyses, Poly‐α‐piperidone, which has a reduced viscosity of 0.7, shows a melting point of 270°C.. which was expected from the zigzag pattern of the correlation between melting points and numbers of CH2 groups for polyamino‐acid polymers.