Transport properties of water in hydroxypropyl methylcellulose

Summary, in English

The relation between the self-diffusion coefficient, D-self, of water and the free volume hole size, V-h, has been investigated in a hydroxypropyl methylcellulose (HPMC)-water system in the water content range 0.08-0.36 w/w, at room temperature. Furthermore, the thermal properties of the water in the HPMC-water system, as measured with differential scanning calorimetry (DSC) and the tensile storage, E', and tensile loss, E '', moduli, of the HPMC-water systems, as determined with dynamic mechanical analysis (DMA), have been probed. Pulsed-field gradient nuclear magnetic resonance (PFG NMR) was used to measure the D-self of water and positron annihilation lifetime spectroscopy (PALS) was used to measure the ortho-Positronium (o-Ps) lifetime in the HPMC-water system. The glass transition temperature of the HPMC was found to be reduced by the water to room temperature in the water content range 0.10-0.15 w/w. The relation between ln D-self of water and the inverse free volume hole size of the HPMC-water system was non-linear. Furthermore, the PALS measurements showed that molecular water co-existed with water clusters in the HPMC-water system. (C) 2009 Elsevier Ltd. All rights reserved.

• Author: Charlotte Trotzig; Susanna Abrahmsen-Alami; Frans Maurer
• Department/s: Centre for Analysis and Synthesis
• Publishing year: 2009
• Language: English
• Pages: 2812-2820
• Publication/Series: European Polymer Journal
• Volume: 45
• Issue: 10
• Links: http://dx.doi.org/10.1016/j.eurpolymj.2009.07.010
• Document type: Journal article
• Publisher: Elsevier
• Topic: Chemical Sciences
• Keywords: Water clusters; Self-diffusion coefficient; Free volume; Positron; annihilation; NMR
• Status: Published
• ISBN/ISSN/Other: ISSN: 0014-3057