In the previous post the UV DSC experimental set-up was described for several commercially available UV DSC systems.  Image on the left courtesy of Perkin Elmer.  The DSC cell design makes if very easy to irradiate a sample in a DSC pan and also determine the accurate baseline to enable quantitative measurements of the heat of reaction during UV curing.  Let’s first discuss ... [Click to Continue...]

In the last few posts, the utility of using a rheometer with a UV exposure accessory was discussed.  The UV rheometer method is very useful for measuring the physical changes during UV exposure, such as how the dynamic loss and storage moduli changed during UV curing.  Monitoring the viscosity as a function of time for various UV exposure doses has important practical uses as ... [Click to Continue...]

In the previous post the role of UV intensity at a constant exposure time was shown to have a large impact on the curing kinetics.  As the UV intensity increased, the time to gelation decreased from the faster chemical crosslinking in an acrylate pressure sensitive adhesive.  Additionally, the UV rheometer data also showed that the modulus at the gel point was approximately the ... [Click to Continue...]

In the last post the UV rheometer method was found to be a very sensitive measurement tool for determining the gel point during UV curing.  As seen in the figure on the left, the crossover in the dynamic loss and storage moduli can be precisely determined yielding an approximate measurement of the time to gelation.  The time to gelation is an important parameter in the ... [Click to Continue...]

In our last post, the experimental methods for measuring the rheological changes to UV exposure were presented.  This post will discuss the impact of UV exposure on the rheological properties such as the dynamic loss and storage moduli.  The thickness of the sample is important in UV curing.  If the sample is too thick, depending on the polymer/initiator combination, the UV ... [Click to Continue...]