Plane stress essential work of fracture of 'pseudo-ductile' gelatin/maltodextrin biopolymer gel composites

Mixed biopolymer gels, comprised of spherical 'maltodextrin-rich' inclusion s within a 'gelatin-rich' continuous matrix phase, have been shown to exhib it a form of 'pseudo-ductility' during tensile deformation, due to debondin g of the inclusion/matrix interface during straining. A plane stress work o f fracture technique, using thin sheet double edge notched tension (DENT) s pecimens, has been applied to these composites to assess the elastic and pl astic contributions to crack growth during fracture. A transition from plan e stress to mixed mode failure was observed to occur when the intact ligame nt length decreased below similar to 8B to 9B (where B is the sheet thickne ss). With the DENT technique, a specific essential work of fracture (elasti c contribution) of similar to 110 J m(-2) was calculated for the current ge latin/maltodextrin composition, under plane stress conditions. (C) 2000 Els evier Science Ltd. All rights reserved.