4. High-modulus oriented fibers and films

In addition to the amorphous and semi-crystalline structures commonly found in polymers, made up of spherulites or crystalline entities arranged in an unordered fashion, there are other types of ordered structures which are widespread in polymers and which contribute to their specific characteristics. Dark-field electron microscopy has been used to determine these structures and their influence on mechanical, optical and electrical properties. This is the case for the following two examples (§ 4 and