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Strain-induced post-curing of acrylate networks |
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| Authors: | Eveline E. L. Maassen Rosaria Anastasio Serena Poto Ruth Cardinaels Rint P. Sijbesma Lambèrt C. A. van Breemen Johan P. A. Heuts |
| Affiliation: | 1. Supramolecular Polymer Chemistry Group, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Eindhoven, The Netherlands;2. Polymer Technology, Department of Mechanical Engineering, Materials Technology Institute, Eindhoven, The Netherlands |
| Abstract: | The mechanical properties and network structure of photocurable polymers are strongly dependent on processing conditions. Here it is reported that highly crosslinked acrylate systems undergo unexpected additional post-curing during DMTA measurements, resulting in an increase in glass-transition temperature (Tg). A detailed study of the conditions under which this increase in Tg takes place unequivocally shows that a small (0.1%) oscillatory strain applied above Tg is responsible for additional cross-linking reactions. The effect of strain-induced post-curing is confirmed by applying post-curing treatments under oscillatory shear strain in rheological tests. Different acrylate systems were characterized and the results show that the strain induced post-curing depends on the network structure of the polymer. In polymer networks with an initial high crosslink density the effect is pronounced while in polymers with an initial lower crosslink density no shift in Tg is observed. |
| Keywords: | glass-transition temperature material characterization mechanical properties multiple cycles DMTA network structure photocurable polymers post-curing |