Cosmetics
Thermoanalytical and Rheological Solutions for Analyzing Cosmetics
Cosmetics are a cultural asset. People have been painting their faces for thousands of years. However, materials, colors and make-up techniques have changed over time and cultural environment – and so have the contents of our beauty case.
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To ensure that decorative cosmetics are of high quality and personal care products can be safely used, raw materials need to be characterized, suitable formulations developed or revised, and manufacturing processes set up and optimized. Along with that, a variety of analytical methods are typically applied, amongst them Thermal Analysis and Rheometry by NETZSCH. They help to find suitable ingredients that meet people’s needs as well as to make cosmetic products “greener” and packaging more sustainable.
How Can You Benefit from Thermal and Rheological Analysis?
Characteristic physicochemical properties of cosmetic ingredients can be measured using various thermoanalytical techniques such as Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), and Simultaneous Thermal Analysis (STA). DSC identifies and determines the Glass Transition TemperatureThe glass transition is one of the most important properties of amorphous and semi-crystalline materials, e.g., inorganic glasses, amorphous metals, polymers, pharmaceuticals and food ingredients, etc., and describes the temperature region where the mechanical properties of the materials change from hard and brittle to more soft, deformable or rubbery.glass transition and/or Melting Temperatures and EnthalpiesThe enthalpy of fusion of a substance, also known as latent heat, is a measure of the energy input, typically heat, which is necessary to convert a substance from solid to liquid state. The melting point of a substance is the temperature at which it changes state from solid (crystalline) to liquid (isotropic melt).melting point of solid, semi-solid or liquid substances and can be used for the investigation of Curing (Crosslinking Reactions)Literally translated, the term “crosslinking“ means “cross networking”. In the chemical context, it is used for reactions in which molecules are linked together by introducing covalent bonds and forming three-dimensional networks.curing reactions; for example, for substances such as nail polish. The Thermal StabilityA material is thermally stable if it does not decompose under the influence of temperature. One way to determine the thermal stability of a substance is to use a TGA (thermogravimetric analyzer). thermal stability of substances are studied by means of TGA. Both methods are commonly applied to check the compatibility of a formulation’s components.
Characterization of the rheological behavior of individual components and final products goes far beyond flow curves and viscosity. Viscoelastic properties, Yield StressYield stress is defined as the stress below which no flow occurs; literally behaves like a weak solid at rest and a liquid when yielded.yield stress, gelation properties, and flow properties of liquids and semi-solids under relevant shear rates are examples of rheological application in the cosmetics field. Yield StressStress is defined as a level of force applied on a sample with a well-defined cross section. (Stress = force/area). Samples having a circular or rectangular cross section can be compressed or stretched. Elastic materials like rubber can be stretched up to 5 to 10 times their original length.stress defines the critical force that has to be applied in order to initiate flow for a substance; for example, so that toothpaste can be squeezed out of a tube. Using the oscillatory mode, you can even get first information about the shelf life of emulsions and suspensions. The Kinexus rotational rheometer and the Rosand high-pressure capillary rheometer cover the broadest shear rate range available on the market, being essential to research, development and quality control for body & care products.