Curing behavior of polymers can be influenced by internal defects or complex structures, among other factors. A full-field, time- and space-resolved visualization of the curing process can help scientists better understand curing kinetics, which is important for many engineering, biomedical and research applications.

By combining optical coherence tomography (OCT) and quantitative phase imaging (QPI), Bo Dong and Bing Pan developed a method to measure the time- and space-resolved curing degree and rate distributions inside a polymer.

Because a polymer’s refractive index variation and shrinkage strain are indicators of its degree of curing, the authors used a series of interference spectra from OCT and QPI to measure the time- and space-resolved distributions of these parameters. By doing so, they were able to monitor the curing process and acquire a visualization of the curing behavior – including the curing rate – within the polymer.

To demonstrate the effectiveness of their method, Dong and Pan observed the gelation and curing processes of different polymer specimens. They were able to distinguish curing degrees and rates at various depths within the polymers.

One of the tests included imaging dental restoration.

“During a dental restoration process, the structure of the cavity may seriously affect the curing behavior of the dental resin,” said Pan.

Using this combination of OCT and QPI, the authors plan to investigate other factors that influence polymer curing. They note this method opens up new possibilities for the understanding of these materials.

Source: “Visualizing curing process inside polymers,” by Bo Dong and Bing Pan, Applied Physics Letters (2020). The article can be accessed at https://doi.org/10.1063/1.5141827.