Secondary (β) Relaxation Process of Alkaline Polycaprolactam Swollen by Low Molecular Weight Substances

By using the method of free torsion vibrations, a detailed dependence was determined of the temperature position and the height of the secondary (β) loss maximum of alkali‐polymerized polycaprolactam upon the concentration of water in the range of 0 < PA < 1.3, where PA is the number of moles of water per mole of monomer units of the portions accessible to the sorption of water. The increase in the secondary loss maximum and the decrease in the height of the low‐temperature loss maximum due to the effect of water in the concentration range 0 < PA < 0.5 is interpreted as consequence of a transformation of the corresponding relaxation processes; subsequent increase in the water content then exhibits only little influence on the height of both the maxima. The β relaxation process is attributed to kinetic units containing amide groups which, owing to interaction with molecules of water, are more firmly bonded to neighboring molecules than the amide groups of a dry polymer. The secondary loss maximum arises also because of the effect of caprolactam monomer and of some low molecular weight amides, being markedly shifted to higher temperatures with the decreasing molecular weight of the amide.