Molecular Motion in Some Glassy Polymers

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Abstract
Molecular motion in several glassy polymers has been examined by proton resonance methods in the temperature range 77–425°K, and has been interpreted in terms of the detailed behavior of molecular chains and substituents. Comparisons are made between transitions seen by proton resonance and glass transitions seen by other methods. Powles' observations on poly(methyl methacrylate) are qualitatively borne out. The influence of thermal history and polymerization conditions is considered. Motion has been examined also in several polymeric methacrylates, including the ethyl, n‐butyl, isobutyl, n‐hexyl, n‐octyl, lauryl. docosyl, and cyclohexyl esters. Some details of molecular configuration are considered for the ethyl ester. In poly(methyl alpha‐chloroacrylate) the low‐temperature values of the second moment are much smaller than expected. These depressed values are ascribed to rotation of all of the methyl groups about the threefold axis.