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Title
Alkyl- chitosan as paper coating material to improve water barrier properties
Authors
RALUCA NICU MIHAIL LUPEI TUDOR BALAN and ELENA BOBU
Received
October 25, 2012
Published
Volume 47 Issue 7-8 July-August
Keywords
chitosan, alkyl-chitosan, functional coating, barrier properties
Abstract
The aim of this study was to obtain and evaluate alkyl-chitosan derivatives as paper coating materials in developing
water barrier properties. Three alkyl-chitosans, differing by alkyl chain length and at two substitution degrees each,
were tested in two coating formulas – polymer and polymer/CaCO3
. Water barrier properties of paper were evaluated
by contact angle (CA), water absorption capacity (Cobb60 index) and water vapour transmission rate (WVTR). The
polymer formula based on alkyl-chitosans improved consistently water barrier properties, which were positively
influenced by substitution degree and negatively by alkyl chain length: the alkyl-derivative with the shortest alkyl chain
and the highest substitution degree led to the highest increase of CA (82.1%) and the highest decrease of Cobb60 index
(82.6%). The WVTR, which depended less on surface hydrophobicity, showed only a slight reduction (only 20.3%)
when using the polymer formula. Coating formulas based on alkyl-chitosan/CaCO3 were more effective than the
polymer formula in reducing Cobb60 index and WVTR, suggesting a more uniform film formation, with lower porosity.
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