Morphology of oriented calcium alginate gels obtained by the flow-gelation method

DOI Web Site Web Site 4 Citations

Bibliographic Information

Published
1991-01
Rights Information
  • https://www.elsevier.com/tdm/userlicense/1.0/
DOI
  • 10.1016/0032-3861(91)90186-m
Publisher
Elsevier BV

Search this article

Description

Abstract Cylinder-shaped oriented gels of calcium alginate were prepared by extruding a 2.6 wt% aqueous solution of sodium alginate (guluronate rich) into CaCl 2 solution through a glass tube. Effects of flow rates on chain orientation in solution and in the gel were examined by polarized optical microscopy. During flow, chains underwent planar orientation along the tube wall, which was reflected in the gel state. Increasing the flow rate increased the coil-stretch transition in solution but led to disorientation of chains in the gel due to increasing die swell and longitudinal shrinkage. This effect resulted in the occurrence of the highest anisotropy of the gel at low flow rate. Chain orientation in the gel was characterized by tilting towards the tangential direction with the appearance of a small negative birefringence, which was transformed to a large positive birefringence on drying due to chain realignment in the longitudinal direction. The morphology of the gel was deduced to be sheet-like structures stacked cylindrically with strong intrasheet binding. Scanning electron microscopy and wide-angle X-ray diffraction were both used in the investigation.

Journal

  • Polymer

    Polymer 32 (16), 2911-2916, 1991-01

    Elsevier BV

Citations (4)*help

See more

Report a problem

Back to top