TABLE OF CONTENTS The analysis of additives in polymers has been reviewed by several workers [1, 2]. A variety of analytical techniques have been considered.
Further details of instrumentation are given in Chapter 3 and Appendix 1.
Spell and Eddy [3] described infrared (IR) spectroscopic procedures for the determination of up to 500 ppm of various additives in polyethylene (PE) pellets following solvent extraction of the additives at room temperature. They showed Ionol (2,6-di- tert-butyl- p-cresol) and Santonox R (4,4'-thio-bis ( 6-tert-butyl- m-cresol)) are extracted quantitatively from PE pellets by carbon disulfide in 2 3 hours and by isooctane in 50 75 hours. The carbon disulfide extract is suitable for scanning in the IR region between 7.8 and 9.3 ?m, while the isooctane extract is suitable for scanning in the UV region between 250 and 350 nm.
Miller and Willis [4] obtained IR spectra of antioxidants in polymer films. They compensated with additive-free polymer in the reference beam. IR spectroscopy is more specific than UV spectroscopy [5 7].
Patticini [8] has described an IR method for the determination of 1 8% of mineral oil in polystyrene (PS). In this method the PS sample is dissolved in carbon tetrachloride, together with known mineral oil standards. The solutions are evaluated by measurements made between 3100 and 3000 cm 1 using a spectral subtraction technique.
Fourier transform near-IR Raman spectroscopy (400 10,000 cm 1) is useful for the examination of additives in polymer extracts [9].
