Role of crystallinity on the thermal and viscous behaviour of polyethylene glycol-in-silicone oil (o/o) phase change emulsions

Role of crystallinity on the thermal and viscous behaviour of polyethylene glycol-in-silicone oil (o/o) phase change emulsions

Stable polyethylene glycol-in-silicone oil phase change emulsions were successfully prepared with aselected silicone surfactant. These oil-in-oil (o/o) emulsions have been scarcely examined up, despitethe highly remarkable properties of both phases for energy recovery applications and cosmetic/pharmaceuticalcompositions. The objective of the present work was to study the effect of composition (surfactantand disperse phase concentrations) and the post-processing conditions (further agitation at theprocessing temperature for 24 h) on the final features of the emulsion. For this purpose, optical morphology,thermo-physical and the rheological behaviour of the emulsions and binary blends of their compoundswere measured and analysed. Special attention has been paid to structural changes andcrystallinity modifications of the emulsion disperse phase. The observed miscibility of the silicone surfactantand silicone chains with the disperse phase reduces its crystallinity degree and modifies in the crystallizationmechanism of the polyethylene glycol, from heterogeneous to homogeneous nucleation. Interestingly, the change in the disperse phase crystallinity remarkably modifies final thermal and rheologicalproperties of the emulsion.

Stable polyethylene glycol-in-silicone oil phase change emulsions were successfully prepared with aselected silicone surfactant. These oil-in-oil (o/o) emulsions have been scarcely examined up, despitethe highly remarkable properties of both phases for energy recovery applications and cosmetic/pharmaceuticalcompositions. The objective of the present work was to study the effect of composition (surfactantand disperse phase concentrations) and the post-processing conditions (further agitation at theprocessing temperature for 24 h) on the final features of the emulsion. For this purpose, optical morphology,thermo-physical and the rheological behaviour of the emulsions and binary blends of their compoundswere measured and analysed. Special attention has been paid to structural changes andcrystallinity modifications of the emulsion disperse phase. The observed miscibility of the silicone surfactantand silicone chains with the disperse phase reduces its crystallinity degree and modifies in the crystallizationmechanism of the polyethylene glycol, from heterogeneous to homogeneous nucleation. Interestingly, the change in the disperse phase crystallinity remarkably modifies final thermal and rheologicalproperties of the emulsion.