Insitu examination of water trees using ir spectroscopy

Studies of the structural and chemical changes of water trees in LDPE are reported. Attenuated total reflection IR spectroscopy was used to examine water tree growth insitu. No increase in polymer oxidation associated with the 1700 to 1750 cm-1 range was observed during tree growth. However, some previously unreported peaks were observed including subtle distortions in the broadband "0-H absorption. Possible peak assignments are discussed. INTRODUCTION Extensive investigation into the initiation and growth of water trees has led to no consensus regarding how the defects form and grow.[l] It has been suggested that polymer oxidation is at least partially responsible for tree formation. In fact, some evidence has been presented which indicates treed regions contain increased amounts of polymer oxidation by-products. A significant amount of evidence has also been presented to the contrary. A recent review of this work has been provided.[ 2 1 Determination of IR spectra of treed regions is not a simple matter. The mechanical abuse and environmental exposure associated with sample preparation can produce changes in polymer spectra. This problem has led to the research described in this paper where spectra of PE containing growing water trees have been acquired insitu.