Related Experiment Video
Updated: May 11, 2026
Molecular Entanglement and Electrospinnability of Biopolymers
Published on: September 3, 2014
Molecular structure of citric acid cross-linked starch films
Carolin Menzel1, Erik Olsson, Tomás S Plivelic
1Department of Food Science, Uppsala BioCenter, Swedish University of Agricultural Sciences, Box 7051, SE-75007 Uppsala, Sweden. carolin.menzel@slu.se
Abstract:
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, 70°C, 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 150°C 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.
More Related Videos
07:06Methods for the Self-integration of Megamolecular Biopolymers on the Drying Air-LC Interface
Published on: April 7, 2017
07:25Green and Low-cost Production of Thermally Stable and Carboxylated Cellulose Nanocrystals and Nanofibrils Using Highly Recyclable Dicarboxylic Acids
Published on: January 9, 2017
Related Concept Videos
03:25Chemistry of Carbohydrates
01:25Production of Organic Acids
03:05Acid Strength and Molecular Structure
In the absence of any leveling effect, the acid strength of binary compounds of hydrogen with nonmetals (A) increases as the H-A bond strength decreases down a group in the periodic table. For group 17, the order of increasing acidity is HF < HCl < HBr < HI. Likewise, for group 16, the order of increasing acid strength is H2O < H2S < H2Se < H2Te. Across a row in the periodic table, the acid strength of binary hydrogen compounds increases with increasing...