CHARACTERIZING AND QUANTIFYING THE AGING OF POLYETHYLENE THIN FILMS USING NOVEL DOPED-FILMS AND GOLD NANOPARTICLE LABELING STRATEGIES TOWARD UNDERSTANDING FAILURE OF CABLING INSULATION

摘要

Under environmental driving forces, the polymerbackbone of the cabling insulations undergo oxidation,scission and crosslinking reactions that ultimately lead tochanges in the physical properties of the plastics. The aimof this work is to develop new methods for quantifyingrates and yields of chemical changes within the relevantinsultation polymers and relate these changes to changesin the electrical barrier properties of the materials.Specifically, novel methods were employed forquantifying oxidation and crystallinity within thin filmsrelying on attenuated total reflectance – Fouriertransform infrared spectroscopy (ATR-FTIR). Oxidationwas quantified using doped films as solid-statecalibration standards. The percent crystallinity was alsodetermined by normalization of amorphous andcrystalline IR-stretches. To observe electrical propertychanges, we applied electrochemical impedancespectroscopy with solutions of either gold nanoparticles(4-6 nm diameter) or a gold salt solution. Under theapplied conditions, a drop in impedance was observedand predicted to be the result of Au3+ ion penetration intothe aged films. Combining the ATR-FTIR measurementsof oxidation and crystallinity, along with the impedancemeasurements, we have established a suite of strategiesfor evaluating polymers that will ultimately enable apredictive model for the failure of these plastics asinsulators of electrical cables.