Enthalpy of mixing

The enthalpy of mixing corresponds to the quantity of heat released or absorbed when two substances—liquids, solids, or polymers—are combined. This thermodynamic parameter makes it possible to assess the compatibility between components and anticipate interaction phenomena (attraction, repulsion, dissolution, molecular association).
In formulation, it is an essential indicator for optimizing the stability , miscibility , and performance of finished products , whether food, cosmetic, pharmaceutical, or polymeric.

Principle and analytical method

The analysis of the enthalpy of mixing is carried out by isothermal titration calorimetry (ITC) , a high-precision technique directly measuring the heat exchanges associated with the mixing reaction.
The principle is based on:

• the progressive injection of one component (solute or polymer) into another (solvent or matrix) at constant temperature;
• real-time detection of heat emitted or absorbed;
• the integration of these signals to determine the molar enthalpy of mixing (ΔHmix).

ITC thus makes it possible to characterize the strength of molecular interactions (hydrogen bonds, van der Waals, electrostatics) and to identify optimal formulation conditions.
For additional studies, also discover differential scanning calorimetry (DSC) , useful for determining thermal transitions and polymer compatibility, or thermogravimetric analysis (TGA) to assess the thermal stability of materials.

Industrial applications

The study of the enthalpy of mixing applies to many fields:

• Cosmetics industry : assessment of the compatibility between emulsifiers, oils, polymers or hydrophilic/lipophilic active ingredients in emulsions and gels.
• Food and nutraceuticals : prediction of the stability of liquid or powder formulations, measurement of the interaction between proteins, polysaccharides and lipids.
• Materials and polymers : characterization of mixtures of polymers, solvents or plasticizers to optimize miscibility and prevent phase separations.
• Packaging and environment : study of interactions between packaging materials and the products contained, or organic mixtures in environmental media.
• Animal and plant nutrition : assessment of the compatibility of additives and excipients in complex food formulations.

This analysis is a valuable tool for formulators, as it allows them to adjust ingredient proportions, prevent physical instabilities and optimize the texture or durability of products.

Analytical interest and associated analyses

The enthalpy of mixing is often combined with other thermal and physicochemical studies for a complete understanding of the interactions:

• Dynamic mechanical analysis (DMA) to evaluate the viscoelastic properties of materials;
• Measurement of interfacial tension to characterize adhesion or wetting phenomena;
• Analysis of powder rheology to study the flow and mixing behavior of granular products.

These complementary analyses allow a multidimensional approach to complex formulations and facilitate the development of stable and high-performance products.

YesWeLab Services

YesWeLab relies on a vast network of ISO 17025 and COFRAC , selected according to your specific needs and the nature of your samples. Our experts guide you towards the best analytical methods for your compatibility, formulation or thermal characterization studies.
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Since 2020, YesWeLab has been supporting manufacturers in the cosmetics, food, materials, and nutraceutical industries with their innovation and quality control projects.
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