Dynamic Power Law Rheokinetic Model for Multifield Coupling in Blocked Polyurethane Elastomers

ABSTRACT The forming quality of blocked polyurethane (BPU) elastomers is critically governed by their rheokinetic response during curing. Nevertheless, existing constitutive models remain constrained by Newtonian assumptions and the absence of shear‐rate coupling, limiting predictive reliability. In this study, rheological characterization across multiple conversion levels, combined with phase‐field normalization, enables the derivation of a power‐law index model coupling temperature and normalized relative viscosity ( α ). This relation reveals a transition from quasi‐Newtonian to non‐Newtonian behavior during curing, with the power‐law index scaling proportionally with ln α and temperature. Within an Arrhenius‐power‐law framework, a dynamic power‐law multifield coupled (DPL‐MFC) rheological model is developed, achieving high‐accuracy prediction of apparent viscosity across broad processing conditions with a global mean absolute percentage error (MAPE) of 0.80%. By further decoupling temperature and shear effects, an α ‐Arrhenius relation is formulated and integrated with the rheological model to yield the DPL‐MFC rheokinetic model. This model resolves the time‐dependent coupling among thermal, chemical, and shear fields, achieving a MAPE of 1.85% under isothermal conditions and extending seamlessly to non‐isothermal regimes. The proposed non‐Newtonian rheokinetic paradigm transcends the limitations of classical models, providing a robust theoretical benchmark for precision manufacturing of advanced thermosetting polymers.