Overview and critical survey of polyamide6 structural habits: Misconceptions and controversies

Abstract

Various aspects of the structural habits and associated thermodynamic properties of polyamide6 are critically examined with regard to controversies that appeared in literature mainly due to misconceptions or erroneous/ambiguous interpretations of experimental findings. The structural habits under concern are the crystallization capabilities and chain topology, hydrogen bonds and sheet-like structure, crystalline polymorphism together with thermodynamic stability. Thermo-mechanical properties are also discussed for the sake of complementary argumentation. Comparisons are made with polycaprolactone, that is, the polyester homolog of polyamide6 regarding chain structure, in order to evaluate the actual role of the H-bonds on the structural habits. Additional comparisons with polyethylene and polypropylene are also made at several occasions for the sake of supporting argumentation on the structural behavior of polyamide6. A temperature–time–transformation diagram of polyamide6 is finally proposed from the gathering of plentiful literature data.