Investigation of acrylates photopolymerisation shrinkage stress

Scientists have published a comprehensive investigation of acrylates photopolymerisation shrinkage stress from micro and macro perspectives.

The shrinkage stress due to resin solidification was monitored in real time to reveal the effect of hollow microspheres.  Image source: DanaTentis - Pixabay (symbol image).

Acrylate photocuring systems with a high curing rate are widely used in various industries. However, the rapid polymerisation kinetics can cause the surge of resin viscosity and the gel point can be reached in advance. This can result in the restriction of molecular chain movement and internal stress release is thus hindered during the photopolymerisation. Finally, it usually leads to the poor performance of UV-cured materials with lower double bond conversion and large volume shrinkage and shrinkage stress.

Effects fully investigated

In order to understand the relationship between properties and polymerisation process, the new paper employed the combined technique of the mid-infrared spectrometer and photo-rheometer to monitor the acrylate free radical photopolymerisation process. The effects of curing conditions (curing temperature, radiant intensity and sample thickness) and system compositions (diluent functionality, diluent segment length) on the rheological properties and chemical conversion of materials were fully investigated.

Finally, a standard protocol was established to evaluate the reactivity, mechanical properties and volume shrinkage of the photocuring system.

The study has been published in Progress in Organic Coatings, Volume 155, June 2021.

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