The role of initial temperature on the yield stress of formulated waxy oils

Abstract Waxy oils exhibit complex rheological behavior at low temperatures. This crystallization process, and consequently the resulting morphology and gel strength, is highly sensitive to the thermal history imposed on the material. While previous studies have documented the influence of the initial cooling temperature ( $$\varvec{T_i}$$ ) on the gelation of crude oils, this work demonstrates for the first time in the open literature that $$\varvec{T_i}$$ also significantly affects the rheological response of formulated waxy oils. Morphological analysis shows that increasing $$\varvec{T_i}$$ leads to a transition from a dense network of numerous small crystals to a sparser structure composed of fewer, larger crystals. To explain this behavior, we propose a hypothesis based on the persistence of subcritical molecular self-assembly precursors in the solution. We suggest that $$\varvec{T_i}$$ dictates the number density of these precursors, which subsequently act as nucleation sites, thereby defining the connectivity and mechanical strength of the wax crystal network.