Large deformation mechanical behavior of gelatin-maltodextrin composite gels

The large deformation failure behavior of gelatin-maltodextrin composite gels was assessed. All the studied compositions were selected to lie within the incompatibility domain of the gelatin-maltodextrin phase diagram at 60 degreesC, which produced gelatin continuous (maltodextrin included) and maltodextrin continuous (gelatin included) composites. Composite microstructural evaluation was performed using confocal laser scanning microscopy (CLSM). The large deformation mechanical behavior was measured in tension and compression experiments. Crack-microstructure interactions were investigated by dynamic experiments on the CLSM. The gelatin continuous composites exhibited pseudo-yielding behavior during tension and compression testing, and there was a significant decrease in modulus that arose from interfacial debonding, Conversely, the maltodextrin continuous composites exhibited an essentially brittle failure behavior, and there was an approximately linear Increase in stress with increasing strain until fracture (which occurred at significantly lower strains than for the gelatin continuous composites). The CLSM observation of the failure of the notched samples also demonstrated interfacial debonding in the crack path; however, this occurred at significantly smaller strains than for the gelatin continuous samples with minimal elastic-plastic deformation of the maltodextrin matrix. The Poisson ratio was estimated to be close to 0.5 for these composites for all Examined compositions. Compositions corresponding to a tie line of the phase diagram were also investigated to assess the influence of the relative phase volume (for constant phase compositions) on the failure behavior. The majority of the parameters subsequently extracted fi om the stress-strain curves were apparently functions of the individual phase volumes. (C) 2001 John Wiley & Sons, Inc.