Temperature effect on water desorption from methylcellulose films studied by thermal FT-IR microspectroscopy |
| |
Authors: | Shan-Yang Lin Shun-Li Wang Yen-Shan Wei |
| |
Institution: | a Department of Medical Research and Education, Taipei Veterans General Hospital, Taipei, Taiwan, ROC b Department of Applied Chemistry, National ChiaYi University, ChiaYi, Taiwan, ROC |
| |
Abstract: | Temperature-induced desorption behavior of water from methylcellulose (MC) film was investigated by a novel microscopic Fourier transform infrared (FT-IR) spectroscopy equipped with thermal analyzer (thermal FT-IR microscopic system) and thermogravimetric analysis (TGA). The result indicates that the weight loss of water from MC film was markedly correlated to the IR spectral changes of OH stretching (3000-3800 cm−1) and bending (1649 cm−1) modes of water molecules. The shift of OH stretching mode from 3461 to 3481 cm−1 was accompanied with the water loss from MC film induced by temperature effect. Two stages of water desorption from MC film were proposed: the first stage within the 35-65 °C had a dramatic IR peak shift from 3461 to 3477 cm−1 and accompanied with a largest weight loss of water from MC film, which might be mainly due to the desorption of free water with minor weakly hydrogen-bonded water; the second stage beyond 65 °C would be desorption of moderately hydrogen-bonded bound water, due to the gradual IR spectral shift from 3477 to 3481 cm−1 and a slower weight loss of water from MC film. The changes in peak area ratio of 1649 cm−1/1374 cm−1 with the temperature also confirmed the IR spectral peak shift of the OH stretching mode via the water loss from MC film. The temperature-dependent dissociation of intermolecular and intramolecular hydrogen bonds within water molecules and/or between water/MC interaction might be responsible for the desorption kinetics of water from MC film. |
| |
Keywords: | Methylcellulose Water desorption Thermal FT-IR TGA Hydrogen bonding |
本文献已被 ScienceDirect 等数据库收录! |
|