Enthalpy Relaxation of Photopolymerized Thiol-ene Networks: Structural Effects
Document Type
Article
Publication Date
9-23-2008
Department
Polymers and High Performance Materials
Abstract
Physical aging behavior of photopolymerized thiol-ene networks was investigated by measuring the extent of enthalpy relaxation in terms of network density and molecular structure. The homogeneous network structure of the thiol-enes, having narrow glass transition temperature ranges, showed characteristic temperature and time dependency relationships for enthalpy relaxation. All thiol-ene films annealed at different temperatures (T-a) for I h according to the isochronal method showed maximum enthalpy relaxation peaks at approximately T-g - 10 degrees C by DSC. The extent of enthalpy relaxation as a function of annealing time (t(a)) was obtained by the isothermal aging method. Correlations between the extent of enthalpy relaxation and the heat capacity difference at T-g were made and related to thiol-ene chemical group rigidity and network linking density. Pendulum hardness values for a selected thiol-ene film showed a clear change in hardness upon aging, indicating sub-T-g mechanical relaxation, consistent with the related enthalpy relaxation process.
Publication Title
Macromolecules
Volume
41
Issue
18
First Page
6741
Last Page
6746
Recommended Citation
Shin, J.,
Nazarenko, S. I.,
Hoyle, C.
(2008). Enthalpy Relaxation of Photopolymerized Thiol-ene Networks: Structural Effects. Macromolecules, 41(18), 6741-6746.
Available at: https://aquila.usm.edu/fac_pubs/1657