Crystallization behavior and mechanical properties of a nylon-6, -6/6, and -12 terpolyamide

Composition, tacticity, and processing history can affect the morphology of semicrystalline polymers. Although homopolyamides are a family of polymers well known for semicrystalline character, through copolymerization or multicomponent copolymerization significant changes in materials' crystalline and thermal properties can occur. Due to chain irregularities introduced by terpolymerization, differential scanning calorimetry shows RDG 114T, a commercial polyamide of nylon-6, -6/6, and 12, to have an atypically low Tm and exhibit interesting recrystallization behavior. Specifically, the polyamide is wholly amorphous upon cooling from the melt, and since its Tg is about 20°C (due to the presence of plasticizers), chain ordering is found to occur over time at room temperature. Since the polyamide's morphology is time-dependent, the tensile properties of the polymer are also found to vary with ambient aging. For instance, Young's moduli for an amorphous and 7-day room temperature-annealed sample are 1.3 × 102 and 2.8 × 102 MPa, respectively.