Relationships between molecular and plane-stress essential work of fracture parameters in amorphous copolyesters

SummaryThe plane-stress fracture toughness of amorphous copolyester (aCOP) sheets of different intrinsic viscosity (IV) was determined by the essential work of fracture (EWF) concept using tensile-loaded deeply double-edge notched (DDEN-T) specimens. It was found that the specific essential work of...

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Bibliographic Details
Published in:Polymer bulletin (Berlin, Germany) Germany), 1997-10, Vol.39 (4), p.503-510
Main Authors: KARGER-KOCSIS, J, MOSKALA, E. J
Format: Article
Language:English
Subjects:
Applied sciences
Cold drawing
Entanglement
Exact sciences and technology
Fracture toughness
Glass transition temperature
Mechanical properties
Necking
Organic polymers
Parameters
Physicochemistry of polymers
Plane strain
Plastic zones
Properties and characterization
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Summary:SummaryThe plane-stress fracture toughness of amorphous copolyester (aCOP) sheets of different intrinsic viscosity (IV) was determined by the essential work of fracture (EWF) concept using tensile-loaded deeply double-edge notched (DDEN-T) specimens. It was found that the specific essential work of fracture (we) is a composite parameter: its constituents are relied on yielding (we,y) and necking (we)/ respectively. The we values, and especially we,y did not change as a function of IV. This finding along with the fact that the mean entanglement length of the aCOP series was constant, suggest that we,y (which is related to the critical plane-strain toughness value) is likely dependent on the entanglement network. This assumption was reasoned by the observation that the plastic zone was completely recovered after annealing the specimen beyond the glass transition temperature (Tg). Recall that the shape recovery in case of cold-drawing (i.e. deformation below Tg) is controlled by the initial entanglement network structure in amorphous polymers.
ISSN:0170-0839
1436-2449
DOI:10.1007/s002890050179