Abstract
Segmented polyurethanes (PU) with crystalline soft segments were prepared with different crystalline polyols as soft segments. Morphology and microstructure of the PUs were investigated using Differential Scanning Calorimetry (DSC), Wide-angle X-ray Diffraction (WAXD), and Positron Annihilation Lifetime Spectra (PALS). Water vapor transport properties of the PU membranes were measured in the temperature range of crystal melting of their soft segments. Dependence of free volume of the PUs on temperature and the relationship between the free volume and water vapor permeability of the PU membranes were investigated. The results show that the mean free volume size and fractional free volume increase more rapidly in the temperature range of crystal melting than in other temperature intervals. In the specified temperature range, water vapor permeability of the polyester based PU membranes increases significantly, caused by the steep increase in free volume, due to crystal melting of the soft segments. Water vapor permeability of the polyester based PUs exhibits approximately direct correlation with the fractional free volume within the temperature range of crystal melting.
| Original language | English |
|---|---|
| Pages (from-to) | 1865-1872 |
| Number of pages | 8 |
| Journal | Journal of Polymer Science, Part B: Polymer Physics |
| Volume | 43 |
| Issue number | 14 |
| DOIs | |
| Publication status | Published - 15 Jul 2005 |
Keywords
- Free volume
- Temperature-sensitive polyurethanes
- Water vapor permeability
ASJC Scopus subject areas
- Condensed Matter Physics
- Physical and Theoretical Chemistry
- Polymers and Plastics
- Materials Chemistry