Design and performance of a thin-film calorimeter for quantitative characterization of photopolymerizable systems

A thin-film calorimeter (TFC) was designed for the quantitative characterization of photopolymerizable systems. A detailed description of its construction indicates the ease with which a TFC can be assembled and the flexibility inherent in its design. The mechanics of operation were optimized to yield a significantly faster instrument response time than other calorimetric methods such as photodifferential scanning calorimetry (photo-DSC). The TFC has enhanced sensitivity, more than an order of magnitude greater linear response range to changes in light intensity than that of the photo-DSC, resulting in the ability to measure both smaller and larger signals more accurately. The photopolymerization exotherm curves are reproducible and can be collected over a broad range of film thicknesses.