Time-Temperature superposition in linear and non-linear domain

Long-term behavior of polymers and their composites is related mainly to their time-dependent mechanical properties, i.e. material functions or master curves, usually obtained by time-temperature superposition (tTS) principle. The weakest point utilizing tTS lies in manual or hand shifting procedure, which can lead to over-or under-estimated life span of polymeric materials. This problem was solved by using closed form mathematical solution called Closed-Form-Shifting (CFS) algorithm which completely removes issues of manual or hand shifting procedure. However, it is important to acknowledge that tTS is well established only within the realm of linear viscoelastic theory. Results have shown that utilizing tTS in non-linear domain, where time-dependent properties become dependent on magnitude of external load, my lead to construction of misleading master curves, i.e. overestimated long-term behavior of polymers that could consequently cause premature failure of polymeric products. (C) 2016 Published by Elsevier Ltd.