Effect of cooling rate on the crystal/mesophase polymorphism of polyamide 6

Morphology of cold-crystallized polyamide 6

“…This may be related to difficult suppression of melt crystallization on cooling which is an urgent requirement to study cold crystallization and/or difficult imaging of structures. It has been found that PA 6 needs to be cooled at a rate of about 150-200 Ks −1 in order to fully vitrify the melt [4,5,24,31]. Such high cooling rate has been achieved in special quenching experiments for preparation of films [4,5] or is effective in surface-near regions of injection-molded parts [32].…”

“…It has been found that PA 6 needs to be cooled at a rate of about 150-200 Ks −1 in order to fully vitrify the melt [4,5,24,31]. Such high cooling rate has been achieved in special quenching experiments for preparation of films [4,5] or is effective in surface-near regions of injection-molded parts [32]. A study of the structure and properties of injection-molded PA 6 revealed formation of a non-spherulitic surface layer consisting of pseudo-hexagonal γ-structure, which demonstrates the effect of cooling rate on structure formation.…”

“…Polyamide 6 (PA 6) is a semicrystalline polymer with the structure and fraction of the ordered phase depending on the condition of crystallization [1][2][3][4][5]. Slow cooling of the relaxed melt at a rate less than about 50 Ks −1 , or isothermal crystallization at temperatures higher about 420 K, leads to formation of monoclinic α-crystals.…”

Rheotens tests and viscoelastic simulations related to high-speed spinning of Polyamide 6

“…Without doubt, however, the two meridian reflexes proof the existence of crystallites. The scattering pattern indicates the formation of a-crystals [30]. We conclude from the WAXS pattern at 3.5 m/s, that in spite of the higher cooling rate, compared to 1.1 m/s, there is now flowinduced crystallization (FIC)!…”

Effects of high cooling rates on solidification for nucleated and non-nucleated semi-crystalline thermoplastics

“…Furthermore, modified cooling conditions affect the development of internal structures of the part. Thus, an increased cooling rate favours the formation of orientations and residual stresses [12,13] as well as an inhomogeneous morphology [14] associated with a modified crystalline structure [15][16][17][18][19][20].…”