Unusual Effects of Monocarboxylic Acids on The Structure and on The Transport and Mechanical Properties of Chitosan Films
2015 (English)In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 132, 419-429 p.Article in journal (Refereed) Published
The purpose of this study was to study the transport of monocarboxylic acids in chitosan films, since this is important for understanding and predicting the drying kinetics of chitosan from aqueous solutions. Despite the wealth of data on chitosan films prepared from aqueous monocarboxylic acid solutions, this transport has not been reported. Chitosan films were exposed to formic, acetic, propionic and butyric acid vapours, it was found that the rate of uptake decreased with increasing molecular size. The equilibration time was unexpectedly long, especially for propionic and butyric acid, nine months. A clear two-stage uptake curve was observed for propionic acid. Evidently, the rate of uptake was determined by acid-induced changes in the material. X-ray diffraction and infrared spectroscopy indicated that the structure of the chitosan acetate and buffered chitosan films changed during exposure to acid and during the subsequent drying. The dried films previously exposed to the acid showed less crystalline features than the original material and a novel repeating structure possibly involving acid molecules. The molar mass of the chitosan decreased on exposure to acid but tensile tests revealed that the films were always ductile. The films exposed to acid vapour (propionic and butyric acid) for the longest period of time were insoluble in the size-exclusion chromatography eluent, and they were also the most ductile/extensible of all samples studied.
Place, publisher, year, edition, pages
2015. Vol. 132, 419-429 p.
Chitosan, Monocarboxylic acids, Uptake, Diffusivity, Mechanical properties
Textile, Rubber and Polymeric Materials
IdentifiersURN: urn:nbn:se:kth:diva-172432DOI: 10.1016/j.carbpol.2015.06.050PubMedID: 26256366ScopusID: 2-s2.0-84936864765OAI: oai:DiVA.org:kth-172432DiVA: diva2:848141
QC 201508252015-08-242015-08-242015-08-25Bibliographically approved