A tensometer to study strain deformation and failure behavior of hydrated systems via in situ environmental scanning electron microscopy.

Large strain deformation and failure behavior of the mixed biopolymer gels have been investigated via in situ Environmental scanning electron microscopy (ESEM). ESEM has been employed to explore the changes in the structure of the material, while allowing the sample to stay hydrated as it was subjected to tensile strain. The “dog-bone” shaped samples were placed in a specially designed tensometer that fitted inside the ESEM specimen chamber. It was possible, therefore, to measure for the first time not only the mechanical properties of the hydrated material, but also to observe any morphological changes occurring as it was being stretched. By using a tensometer capable of keeping a sample moist over large strains, it was possible to observe hitherto unreported structural changes in gelatin-based systems subjected to uniaxial stretching. It was shown that bands were formed in the direction of the applied strain and that particles of maltodextrin included in the gelatin underwent deformation and fracture. Such observations have led to the conclusion that previous models were sometime inadequate due to the lack of in situ observation and novel approaches are required to describe these phenomena. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]