Generalised superposition models for rheologically complex starch-nanohybrid films and integrational construction of master-curves

Abstract

We propose an integrational method to construct master-curves, using synthetic simultaneous multifrequency scans to avoid intrinsic temperature control variances and better predict Tg and Tm. Proposed generalised time–temperature superposition models for rheologically complex materials are presented. The methodologies and models were applied to thermoplastic starch films modified with polyhedral oligomeric silsesquioxanes (POS). We confirmed their thermorheologically complex behaviour, which in principle cannot be used to construct master curves. However, based on properties predicted by the models, we were able to establish temperature constraints where the time-temperature principle was valid. Our models have higher coefficient of determination than the Williams–Landel–Ferry (WLF) or Arrhenius models currently applied in rheologically simple materials. The addition of POS increased the internal ordering of the films, leading to more compact molecular arrangement, made the films more resilient to deformation and their master-curves begin at higher frequencies than the control.