Nuclear magnetic resonance imaging of electrical trees in PE

Test samples of LDPE (low-density polyethylene) were electrically aged until PD (partial discharge) and electrical treeing occurred. Investigations on the spatial distribution of microscopic domain sizes in the lamellar morphology of the samples were carried out applying a novel method of proton NMR imaging which probes magnetization transfer by spin diffusion. Spatial changes of LDPE morphology are detected due to the appearance of PD.