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Polymers 2016, 8(5), 197; doi:10.3390/polym8050197

Microstructure Changes in Polyester Polyurethane upon Thermal and Humid Aging

1
Key Laboratory of Neutron Physics and Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621999, China
2
Department of Macromolecular Physics, Faculty of Mathematics & Physics, Charles University, Prague 180 00, Czech Republic
3
Institute of Chemical Materials, China Academy of Engineering Physics, Mianyang 621999, China
4
Wigner Research Centre for Physics, Institute for Solid State Physics and Optics, P.O. Box 49, Budapest H-1525, Hungary
*
Authors to whom correspondence should be addressed.
Academic Editor: Antonio Pizzi
Received: 17 March 2016 / Revised: 8 May 2016 / Accepted: 11 May 2016 / Published: 20 May 2016
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Abstract

The microstructure of compression molded Estane 5703 films exposed to 11%, 45%, and 80% relative humidity and 70 °C for 1 and 2 months has been studied by small-angle neutron scattering (SANS), Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), and differential scanning calorimetry (DSC). Scattering data indicated increase of the interdomain distance and domain size with a higher humidity and longer aging time. GPC data showed a progressive shortening of polyurethane chains with increasing humidity and aging time. The shortening of the polyurethane chains caused a drop of the glass transition temperature of soft segments, and promoted crystallization of the soft segments during long-time storage of the aged samples at room temperature. FTIR showed a substantial increase in the number of inter-urethane H-bonds in the aged samples. This correlates with the increase of the hard domain size and the degree of phase separation as measured by SANS. The data collected reveals that the reduced steric hindrance caused by hydrolysis of ester links in polybutylene adipate residues promotes the organization of hard segments into domains, leading to the increase of domain size and distance, as well as phase segregation in aged Estane. These findings provide insight into the effects of humidity and thermal aging on the microstructure of aged polyester urethane from molecular to nanoscale level. View Full-Text
Keywords: SANS; IR; polyurethane; aging; microstructure SANS; IR; polyurethane; aging; microstructure
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

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MDPI and ACS Style

Tian, Q.; Krakovský, I.; Yan, G.; Bai, L.; Liu, J.; Sun, G.; Rosta, L.; Chen, B.; Almásy, L. Microstructure Changes in Polyester Polyurethane upon Thermal and Humid Aging. Polymers 2016, 8, 197.

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