Macromolecular Orientation in Glassy Starch Materials That Exhibit Shape Memory Behavior

• Published in: Macromolecules Vol. 43; no. 23; pp. 9854 - 9858
• Main Authors: Véchambre, Cyril, Buléon, Alain, Chaunier, Laurent, Jamme, Frédéric, Lourdin, Denis
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 14.12.2010
• Subjects: Applied sciences; Biological and medical sciences; Engineering Sciences; Exact sciences and technology; Food industries; Fundamental and applied biological sciences. Psychology; Materials; Natural polymers; Physicochemistry of polymers; Starch and polysaccharides; Starch and starchy product industries; Hot deformation; Molding; Glycerol; Experimental study; Mechanism; Humidity effect; Molecular orientation; Plasticizer; Oriented polymer; Shape memory effect; Potato starch; Oside polymer; Amorphous polymer; Thermoplastic starch; Residual stress
• ISSN: 0024-9297; 1520-5835
• DOI: 10.1021/ma101704k

This paper explores the molecular mechanisms involved in residual stress in relation with shape memory effects in glassy amorphous starch. Wide-angle X-ray scattering (WAXS) and synchrotron radiation (SR) polarized infrared microspectroscopy were used to analyze the structural anisotropy revealed by polarized light microscopy. A local molecular orientation was evidenced by WAXS and IR dichroism. Results clearly demonstrate that the residual stress observed in the temporary shape is due to local molecular orientation in amorphous starch resulting from the flow of matter induced by the deformation process. The molecular orientation disappears when the sample relaxes and recovers its initial shape.