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Rheology of photosensitive materials

Photochemical-induced curing using high-intensity ultraviolet (UV) radiation (UV curing) offers several advantages over conventional industrial processes. Photosensitive materials are characterized, among other things, by faster curing reactions and better surface properties. In addition, the use of solvents and the resulting environmentally harmful vapors can be discarded. Thanks to these and other properties, UV-curing-sensitive materials are becoming increasingly important in many areas, such as in paint, coatings, and adhesives industries. Additionally, photochemical curing is the basis for various additive manufacturing processes. Rheology is an established measurement method to investigate the change of sample properties before, during, and after such photolytic curing reactions and to support new material development.

Advantages of UV curing

UV-curing applications

UV-curable materials are widely used in coatings, adhesives, sealants, potting compounds, and inks, which are used in various industries such as automotive, 3D printing, medical, and electronics.



Quickly achieving functional and reliable bondings between material surfaces in seconds is imperative for different industries such as in electronics, medical, and automotive manufacturing.

UV Coatings


Developing fast-curing surface finishes leads to increased production capacity and processing speed for industrial and consumer applications such as automotive, medical, or cosmetic applications.

medical applications

Medical applications

Advancing UV-curable materials is crucial for superior performance of dental applications and UV-supported manufacturing processes of contact lenses.


Additive manufacturing (3D printing)

Investigation of the curing behavior as well as the occurring shrinkage of photocurable materials during the 3D printing process in the stereolithography process is important.

Types of UV curing

How to select the right UV light source for your application

High-pressure discharge lamps based on mercury (mercury-vapor lamps) are often used as UV radiation sources for rheological measurements. However, LED lamps are establishing themselves as a popular alternative due to major advances in diode technology.

Mercury-vapor lamps

The operating principle of mercury-vapor lamps is based on the vaporization of mercury as a result of an ignition. This leads to the emission of a broad spectrum of different wavelengths. Specific wavelength ranges can be selected from this spectrum using optical filters. For example, an OmniCure® S2000 UV light source can cover wavelengths from 320 nm to 500 nm as standard. Other filters are available on request.

UV LED light sources

UV LED light sources are based on semiconductor components that emit an almost monochromatic wavelength spectrum when an electrical current is applied. The emitted spectrum is specific to the semiconductor material used. As a result, UV LED lamp heads, such as the DELOLUX 50 can be used to cure photosensitive materials at specific wavelengths of 365 nm, 400 nm, and 460 nm. Further wavelengths are available on request.

UV light source comparison

Übersicht UV light sources

UV-curing systems

Rheological characterization of photosensitive materials

Our series of Thermo Scientific HAAKE MARS 40 / 60 Rheometers includes a comprehensive portfolio of UV-curing measuring cells tailor-made for your applications. These include thermally assisted UV-curing at elevated temperatures and the unique combination of simultaneous rheology and FTIR spectroscopy to meet incoming and outgoing QC requirements and R&D for material and process development.

Additional advantages of the UV-curing configurations with the HAAKE MARS 40/60 Rheometers:

  • Simple, reproducible measurements
  • Modular adapter solutions can be easily added to the different MARS Rheometer configurations
  • LED or mercury light sources to meet different needs
  • Disposable measuring geometries with different dimensions for testing up to the fully cured state
  • Unique pneumatic geometry release function for easy exchange and hassle-free removal of glued geometries

The Thermo Scientific HAAKE RheoWin Measuring and Evaluation Software can be used to create complete measurement and evaluation routines for UV-curing tests, including:

  • Visual user guidance via images or video clips
  • Various data evaluation routines
  • Data export in different formats
  • Report generation with customizable layout
Thermo HAAKE
UV-curing measuring cell.
Thermo Kopie
Simultaneous rheology with FTIR spectroscopy.

UV-curing portfolio overview

Universal Peltier temperature module for UV-curing applicationsUV-assisted thermal curing at elevated temperaturesUV curing for advanced measurements with combined spectroscopy
A flexible UV-curing module with built-in Peltier temperature control enabling an easy and fast exchange between the UV-curing setup and regular rheological configurations for coaxial cylinder or parallel plate / cone and plate measuring geometries.A UV light adapter for the CTC (controlled test chamber) oven for UV-assisted thermal curing over a very wide temperature range.The combination of a rheometer with FTIR spectroscopy for R&D applications. A UV module for the temperature-controlled Thermo Scientific Rheonaut Module for HAAKE MARS Rheometer is available. Simultaneous collection of rheological data and FTIR spectra is enabled to investigate structural changes within the sample during curing.
A universal Peltier temperature module with two optional adapters enables three measuring options for highest flexibility at low cost.
- Measurements with coaxial cylinder geometries.
- Adapter plate for parallel plate or cone and plate geometries.
- UV adapter for rheological investigation of curing reactions initiated by UV light irradiation. The UV light source can be triggered automatically by the HAAKE RheoWin Rheometer Control Software.
For thermal-assisted curing across a wide temperature range, a UV cell is integrated into the CTC of the HAAKE MARS Rheometer.
Using the HAAKE RheoWin Software, it is possible to program an automatic measuring routine in which the sample is first pre-cured by the UV light and then thermally cured using the CTC. The combination of convection and radiation heating guarantees fast temperature changes and an even temperature distribution within the CTC oven.
This UV curing includes a rotor with a built-in mirror and a glass plate, and it can be used with different standard-temperature modules for plates as well as with the Rheonaut System. The Rheonaut System enables the simultaneous application of rheometry and FTIR spectroscopy to generate a better understanding of the structural changes during curing reactions.
Up to 180°C*Up to 600°C*Up to 200°C*
Light source: LED or mercuryLight source: LED or mercuryLight source: LED or mercury

* Highest temperature for the UV module.
Note: This temperature range may be limited by the maximum temperature for which the UV light source and the components used with it (e.g., light guides) were designed.

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*OmniCure® is a registered trademark of Excelitas Technologies Corp.

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