Photodifferential scanning calorimetry

Cho and Hong (2005) used photodifferential scanning calorimetry to investigate the photocuring kinetics of UV-initiated cationic photopolymerization of 1,4-cyclohexane dimethanol divinyl ether (CHVE) monomer with and without a photosensitizer, 2,4-diethylthioxanthone (DETX) in the presence of a diaryliodonium-salt photoinitiator. Two kinetic parameters, the rate constant (k) and the order of the initiation reaction (m), were determined for the CHVE system using an auto-catalytic kinetics model as shown in the following equation ... 

Oxman et al., smdied controlled, sequentially curable cationic/free radical hybrid photopolymerization of diepoxide/acrylate hybrid material with the aid of photodifferential scanning calorimetry. The polymerizations were carried out in the presence of various concentrations of either ethyl-4-dimethylamino benzoate or 4-tert-butyl-N,N,-dimethylaniline as electron donors and camphoquinone/diphenyliodonium hexafluoroantimonate as the sensitizing system. The results showed that the free-radical acrylate reactions always precede the cationic epoxy polymerizations. 

Techniques for Measuring Rates and Reactive Intermediates. Kinetic parameters for photopolymerizations may be measured using many different methods or combinations of methods (9,68). Photodifferential scanning calorimetry (PDSC) is a standard technique for obtaining the rate of polymerization (i p) and conversion (69-73). The conversion of monomer C=C bonds to polymer C—C bonds is an exothermic reaction. The heat flow fi om the sample (AH in W/g) is directly proportional to Rp ... 

Fig. 7. PhotodifFerential scanning calorimetry profiles for photopolymerization of 2-hydroxyethyl methacrylate initiated with 2 mmolal dimethoxyphenylacetophenone at 50°C and light intensity of 60 mW/cm with nitrogen purge polymerization rate (left) and degree...

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