Molecular structure of citric acid cross-linked starch films
Author
Summary, in English
The effect of citric acid (CA) on starch films has been examined. A new method to detect cross-linking of starch by CA in solution-cast films by molecular weight measurements is described. Furthermore, we managed to distinguished between free, mono- and di-esterified CA and quantify di-ester content within starch films by using a modification in the method of complexometric titration with copper(II)-sulfate. Cross-linking of starch by CA occurred at low temperature, 70C, which we assumed is so far the lowest temperature reported where cross-linking reaction occurred. This is essential for starch coating applications within paper industry since no high temperatures for curing will be required. However, curing at 150C and high CA concentrations, 30 pph, increased cross-linking reaction. Furthermore, the physical properties like water solubility, gel content and glass transition temperature, were highly reflected by changes in the molecular structure i.e. cross-linking and hydrolysis, as well as CA content and curing temperature.
Department/s
Publishing year
2013
Language
English
Pages
270-276
Publication/Series
Carbohydrate Polymers
Volume
96
Issue
1
Document type
Journal article
Publisher
Elsevier
Topic
- Physical Sciences
- Natural Sciences
Keywords
- Starch-base films
- citric acid
- cross-linking
- molecular weight
- hydrolysis
- amorphous starch
- plasticization
Status
Published
ISBN/ISSN/Other
- ISSN: 0144-8617