THERMAL, MECHANICAL AND WATER SORPTION PROPERTIES OF XANTHAN-BASED COMPOSITE CRYOGELS

The thermal, mechanical, rheological, and surface characteristics of some xanthan/poly(vinyl alcohol)/red grape pomace composite cryogels prepared by the freeze/thawing approach were investigated. The results were discussed in comparison with those obtained for individual xanthan or poly(vinyl alcohol) cryogel networks synthesized under the same conditions. The mechanical strength of the cryogels was enhanced by increasing the number of freeze/thawing cycles, and by the addition of a natural polyphenol (i.e. red grape pomace). The thermal stability of the poly(vinyl alcohol) in the blend significantly decreased upon the addition of 50% xanthan, while the presence of a single neat melting profile indicated good component miscibility for the chosen ratios. The water sorption capacity depended on the amount of polyphenol incorporated, thus the hydrophilicity of the cryogel films decreased with the increase of polyphenol content.