Near Infra-Red Pleochroism. I. The Perturbed O–H and the C–H Modes in Polyvinyl Alcohol

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Abstract
Pleochroism in O–H···O–H bands and > CH2 bands of polyvinyl alcohol is studied in the 0.6–3.7μ‐region, using a quartz recording spectrograph in the 0.6–2.7μ‐region and a high dispersion grating instrument with a selenium polarizer in the 2.5–3.7μ‐region. Weak pleochroism in the fundamental ν(O–H) bands suggests that either some of the conclusions drawn from x‐ray determinations may be in error or that there may be appreciable departure of the positions of the H atoms from the O–O lines. Dichroic bands caused by bound water are also found in this region, complicating interpretation and perhaps explaining discrepancies between this work and that of Elliott, Ambrose, and Temple. Evidence is presented for the presence of ``free'' carbinol O–H units in the crystalline regions of well‐dried specimens. Pleochroic bands at 2941 cm−1 and 2906 cm−1 are tentatively assigned to > CH2 νa and νs fundamentals, respectively.