DYNAMIC-MECHANICAL STUDIES OF THE GLASS-TRANSITION TEMPERATURE OF PHOTOPOLYMERIZED MULTIFUNCTIONAL ACRYLATES

The glass transition temperatures of the highly crosslinked networks formed from photopolymerizing the multifunctional monomers trimethylol propane triacrylate (TrMPTrA), pentaerythritol tetraacrylate (PETeA), and dipentaerythritol monohydroxy pentaacrylate (DPEMHPeA) were determined using a dynamic viscoelastometer. All glass transition temperatures, T(g), were in excess of 150-degrees-C indicating the highly crosslinked structure of the resulting networks. The curves of the damping factor as a function of temperature were broadened peaks spanning up to 100-degrees-C due to the extreme heterogeneity of these structures. Evidence of trapped radicals was also observed as cured samples subjected to a thermal pretreatment had higher T(g) than those without the thermal pretreatment.