Facile Characterization of Isothermal Crystallization and Microphase Separation Kinetics of Polyamide 6 (PA6)-Based Thermoplastic Elastomers

The facile characterization of isothermal microphase separation kinetics in polyamide 6 (PA6)-based thermoplastic elastomers (TPAE-6) has long posed a challenge for the development of suitable melt spinning processes. In this study, this challenge is addressed through differential scanning calorimetry (DSC) measurements. It is assumed that the enthalpy changes of TPAE-6 during the isothermal process are a linear superposition of enthalpy changes associated with microphase separation and crystallization of PA6 in hard phases, resembling that of TPAE-6 without soft segments (TPAE-6-0). The study reveals that, as the concentration of soft segments in TPAE-6 increases, the accelerated dynamics of phase separation become stronger than the dilution of soft segments to PA6 segments during isothermal process, resulting in an increase in the microphase separation rate of TPAE-6. Furthermore, despite microphase separation, the overall crystallization rate of TPAE-6 decreases with rising isothermal temperature and varies with increasing soft segment content at different temperatures. Additionally, the crystallization mode of TPAE-6 follows two-dimensional, three-dimensional, or a combination of both crystal growth mechanisms, accompanied by a heterogeneous nucleation mechanism.