[5.] ISO 16770, Plastics--Determination of Environmental Stress Cracking (ESC) of Polyethylene--Full-Notch Creep Test (FNCT
), ISO 16770, CEN, Brussels (2004).
This study indicates the insight into the micromechanism of deformation and fracture due to slow crack propagation during the FNCT test.
All the samples received are HDPE pipe grade and selected based of their relative FNCT failure time.
For the morphological characterization, the samples received are in the form of fractured FNCT bar where the area dimension is 10 mm x 10mm.
Four different samples based on the FNCT results are taken for the study.
Apart from the micrographs of side surface for these FNCT fracture samples, the overview of the top surface for these fracture samples were also recorded and these micrographs are shown in Figure 3.
The micrographs of all the samples (Figure 7) are captured to see the impact of FNCT behaviour on the dimple pattern in the fractured surfaces.
In the FNCT test, the solvent used acts as stress cracking agent to promote crazing and cracking.
The fracture surface of FNCT bar made of HDPE shows the brittle behavior on the macroscopic level but the ductile behavior at micro scale.