Modelling tensile force oscillation during the tensile test of PET specimens

Abstract

Abstract. Force oscillation occurring during the tensile testing of poly(ethylene terephthalate) (PET), resulting in periodical cavitation of the test specimens, has been studied. A mathematical model has been developed to describe the phenomenon, wherein special fibre bundles are assigned to the amorphous molecular chains. In order to model the local periodical transformations and the rate dependent viscoelastic behaviour the coupled fibre bundle cells were supplemented with a twoelement Maxwell model. Using the parameters determined from the measurements the model was compared to the measured force-elongation diagrams and it has been concluded that the simple model can be well used to describe the phenomenon.

Stress-oscillation behaviour of semi-crystalline polymers: the case of poly(butylene succinate)

“…Similar observations were reported in PET 42 where the cavitation formed inside of the samples. At a certain strain rate, the aPET chains were sheared and orientated, creating fiber bundles and crazes.…”

Fracture behavior of boehmite‐filled polypropylene block copolymer nanocomposites as assessed by the essential work of fracture concept

“…This kind of instability appeared also in the F‐x curves, resulting “waves” in the force trace [see Figure (e), L = 17 mm]. This phenomenon is similar to the stress‐oscillation behavior at tensile tests of some thermoplastic materials . The formed wavy borderline is indicated by white arrow in Figure (b).…”

An investigation of stress oscillation in poly(butylene succinate‐co‐cyclohexanedimethylene succinate)

“…In the previous studies, a two‐element Maxwell model with fiber bundle cells is proposed to predict stress oscillation . According to this model, the changes in the orientation of molecular chains are modeled by fiber bundle cells.…”