Large deformation mechanical behavior of gelatin-maltodextrin composite gels

The large deformation failure behavior of gelatin-maltodextrin composite ge ls was assessed. All the studied compositions were selected to lie within t he incompatibility domain of the gelatin-maltodextrin phase diagram at 60 d egreesC, which produced gelatin continuous (maltodextrin included) and malt odextrin continuous (gelatin included) composites. Composite microstructura l evaluation was performed using confocal laser scanning microscopy (CLSM). The large deformation mechanical behavior was measured in tension and comp ression experiments. Crack-microstructure interactions were investigated by dynamic experiments on the CLSM. The gelatin continuous composites exhibit ed pseudo-yielding behavior during tension and compression testing, and the re was a significant decrease in modulus that arose from interfacial debond ing, Conversely, the maltodextrin continuous composites exhibited an essent ially brittle failure behavior, and there was an approximately linear Incre ase in stress with increasing strain until fracture (which occurred at sign ificantly lower strains than for the gelatin continuous composites). The CL SM observation of the failure of the notched samples also demonstrated inte rfacial debonding in the crack path; however, this occurred at significantl y smaller strains than for the gelatin continuous samples with minimal elas tic-plastic deformation of the maltodextrin matrix. The Poisson ratio was e stimated to be close to 0.5 for these composites for all Examined compositi ons. Compositions corresponding to a tie line of the phase diagram were als o investigated to assess the influence of the relative phase volume (for co nstant phase compositions) on the failure behavior. The majority of the par ameters subsequently extracted fi om the stress-strain curves were apparent ly functions of the individual phase volumes. (C) 2001 John Wiley & Sons, I nc.