Spectroscopy in the Rubber Industry

Abstract

Abstract The kinds of spectroscopy to be discussed in this review are those which yield organic structural information and involve the nondestructive interaction of electromagnetic radiation with polymers of interest to the rubber industry. For those forms of spectroscopy which meet this rather restrictive definition, their use with nonpolymeric compounds of importance to the rubber industry will be included. In accord with these criteria, proton magnetic resonance (PMR), carbon-13 magnetic resonance (CMR), electron spin resonance (ESR) and ultraviolet (uv) spectroscopy will be discussed in this review. Infrared spectroscopy, which is of great importance to the rubber industry, has been the subject of a recent Rubber Review by R. W. Hampton and will therefore not be reviewed here. Using this definition, mass spectrometry will not be discussed, since it cannot be applied to polymers without first fragmenting them by pyrolysis. X-ray fluorescence spectroscopy is extremely useful for detecting and measuring metallic impurities in polymers (elements of atomic weight greater than A1). Because the polymers of this review are composed largely of elements lighter than Al (C, H, N, O), x-ray fluorescence is not useful for the study of the polymer itself. This is largely true also for x-ray diffraction (XRD) where noncrystalline polymers yield XRD patterns characteristic of liquids, which can yield information from which the average distance between molecules can be calculated. For partly crystalline polymers, XRD yields information from which the extent of crystallization, the size of polymer crystallites and their arrangement in the bulk polymer can be calculated. This morphological information goes beyond the basic organic structure of interest to organic chemists, and x-ray spectroscopy will not be discussed in this survey.