Article ID Journal Published Year Pages File Type
1386643 Carbohydrate Polymers 2007 6 Pages PDF
Abstract

We have investigated the thermal expansion of mannan I crystals obtained from the endosperm of ivory nuts using X-ray diffraction in the temperature range of from room temperature to 250 °C on heating. Seven major diffractions were observed, and all the d-spacings gradually increased with increasing temperature. However, discontinuities indicating a phase transition were observed at a temperature of 130 °C. The unit cell parameters showed an anisotropic thermal expansion between the intermolecular hydrogen bonded direction and the covalently bonded direction, where the a and b axes lengths increased, but the c-axis length decreased with increasing temperature. Although the reason for the contraction of the c-axis length on heating is not clear, the thermal behavior should be related to the crystal structure and hydrogen bonding system of mannan I.

Related Topics
Physical Sciences and Engineering Chemistry Organic Chemistry
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