Effect of part thickness on the potential to induce cold crystallinity in nylon 6,6 injection molded samples

Tensile bars of two different thicknesses were injection molded from Nylon 6,6 under controlled conditions and DMA results compared. Early analysis indicates that cold crystallization can be induced for improved mechanical properties on the 2mm thick samples, but not for the 4mm samples. This is due to the more prominent shear-induced orientation layers inherent in the thinner sample re-orienting during the annealing process. Results indicate there may be applications where the crystalline distribution through the thickness of a part may be critical to the plastic performance in cyclic or thermal load bearing applications.