2.5 - Mechanical properties of polymeric materials

Abstract

Polymeric materials are used more and more not only as commodity materials—in packaging, containers, fibers, and also in technical applications in the aeronautics and automotive industries. In these latter cases, high technical performance is required, such as temperature resistance, high modulus, and toughness. This chapter describes the various types of polymer structures and presents their mechanical properties, emphasizing the responses specific to these materials. In many cases, the macromolecular chain consists of the repetition of a single chemical unit. In addition to the types of units that are present, an important feature that controls the mechanical properties of polymers is the chain macrostructure. The various types of polymer macrostructures are (1) linear chains—many thermoplastic polymers like PS, PMMA, PA66, and PETP have linear chains; (2) branched chains—long chain branching can result either from the addition of a small amount of a specific unit leading to the growth of a new polymer chain on the backbone of a polymer or from side reactions; (3) polymer networks—in all elastomeric materials the polymer chains are cross-linked by chemical agents in order to prevent the flow of the material under strain and to obtain an elastic response.