ISSN:
0021-8995
Schlagwort(e):
Chemistry
;
Polymer and Materials Science
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
,
Maschinenbau
,
Physik
Notizen:
Chiroptical methods have been used to study the conformation and interactions of amylose and amylopectin with poly(ethylene co-acrylic acid) (EAA) in aqueous solution. These studies, along with X-ray diffraction and solid-state NMR data, show that amylose and EAA, as well as amylopectin and EAA, form helical V-type inclusion complexes when mixed in aqueous suspension. This structure apparently accounts for the partial compatibility observed in films containing starch and EAA. About 2/3 by weight of EAA does not interact with amylose and probably represents the ethylene-rich central core of the EAA micelle. EAA/amylose complexes in 10 mM NaOH were stable to temperatures 〉 90°C, whereas EAA/amylopectin complexes in the same solvent were largely disrupted at this temperature. Urea, at a concentration of 8 M, further destabilized both EAA/amylopectin and EAA/amylose complexes. Solutions with an alkaline pH (〉 9.5) dispersed EAA optimally and allowed maximum complexing with amylose. At pH values 〉 13, the EAA/amylose complexes were weaker, most likely due to electrostatic repulsion between ionized hydroxyl groups of amylose and carboxyl groups of EAA.
Zusätzliches Material:
8 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/app.1991.070420625
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