Instrumental Methods for the Analysis of Polymeric Materials

Abstract

Abstract Advances in our knowledge of the chemical and physical structure of polymeric substances have been due in large measure to new and improved instrumental methods of analysis. From the standpoint of chemical structure all polymers have at least one functional group, often in low concentration, e.g., an end group. Principal progress has been made, first, in identification of these groups, and, more recently, in their quantitative determination and location within the molecule. In some cases conventional chemical methods have been greatly improved to provide the high sensitivity required for these analyses, particularly for groups such as acid, amine, ester and carbonyl. However, most chemical methods depend on reaction in solution. Often the choice of solvent is limiting, since it must be inert toward both the sample and the reagents as well as be capable of dissolving a significant amount of the material to be analyzed. In many cases a suitable solvent is not available. Many of these restrictions do not apply to instrumental techniques. Infrared spectrophotometric methods, for example, may be (a) nondestructive and the sample can be recovered for other studies, (b) rapid, often being completed within several minutes, (c) direct in which films or dispersions can be handled and, therefore, limited solubility is not a problem, (d) capable of providing information on physical as well as chemical structure, and (e) capable of supplying other useful information during the course of an analysis. Examples of techniques used in analyses for chemical and physical structure are: (see PDF for table) This paper reviews primarily recent advances in instrumental techniques which have been shown to be capable of quantitative analysis for chemical structure. Also, reference is made to the use of infrared spectroscopy, nuclear magnetic resonance spectroscopy, and differential thermal analysis in studies of physical structure. Applications to characterizations of elastomers are emphasized, although for illustrative purposes investigations of other polymers often are discussed.