A Fourier Transform Infrared spectrometer equipped with a microbeam accessary and a linear translation stage with a pinhole mask was used to monitor the diffusion of antioxidant in crosslinked polyethylene (XLPE) matrices crosslinked with controlled amounts of crosslinking agent. Integration of the peak area for a characteristic peak of the antioxidant at different positions along the sample indicated the changing concentration due to diffusion within 30 days. This technique allowed us to study an antioxidant with a molecular weight in the thousand range. The diffusion coefficients calculated were in the order of 10−11 – 10−10 cm2·s−1. It was observed that the diffusion constants dramatically changed with the crosslinking density.
Combining supercritical fluid chromatography and Fourier transform infrared spec1:roscopy has been described in a number of reports. This work i s concerned with developing an automated combined micro Fourier transform infrared spectroscopy with a micro extractor SFC interface. The instrument i s described in detail. Basically i t consists of a computer driven collector drum complete with cooling assembl*y that i s attached to the exit of an SFC extractor which can be controlled as to temperature and pressure.This permits some preliminary fractionation. The interface i s then moved to micro FTIR. The computer then i s used to position the co1lect.ed areas successively under the FTIR and mu1 tiple scans are made to any desired level. Examples are given of the performance on extracts from asphalts.
Abtract Measurements have been made o f the AC breakdown strength and the impulse breakdown strength o f samples o f XLPE t o which known amounts o f acetophenone, cumyl alcohol, alpha methyl styrene and cumene were added. A Weibull analysis o f the breakdown strengths shows t h a t t h e presence o f small amount (1.es.s than 2 ut%) o f these substances) has a small e f f e c t on the breakdown strength o f unaged XLPE.
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