Adiabatic polymerization of ε‐caprolactam in presence of lithium chloride, 2. Properties of the resultant polymer

Physical and mechanical properties of poly(ε‐caprolactam) synthesized in presence of various amounts of lithium chloride are measured on compression moulded films and correlated to the molecular organization, both in the amorphous and in the crystalline regions. By increasing the amount of LiCl present in the system it can be observed a heigtening of Tg and density of the amorphous phase as well as an increase of tensile modulus and yield strength. A transition from ductile to brittle failure occurs for both semicrystalline and amorphous samples in dry conditions, when the salt content in the amorphous phase is about 6 wt.‐%. These phenomena and the capability of the salt to reduce the crystallinity of the polymer are interpreted in the frame of the already accepted model of ion‐dipole interactions between lithium ion and the carbonyl groups of the polyamide. Effects due to moisture uptake are also discussed.