The Molecular Structure and Mechanical Properties of Polyethylene Terephthalate Fibers

In this paper, the application of several techniques of molecular structure deter mination to polyethylene terephthalate (henceforth abbreviated to PET) polymer and fibers will be described. These investigations have been directed partly towards obtain ing an understanding of the dynamic mechanical properties of PET and related polymers and partly to the characterization of PET fibers with respect to crystallinity and orientation. In considering the dynamic mechanical properties of PET and their relationship to the molecular structure two main points have been investigated: first whether the dynamic mechanical transitions can be related to specific motions of the molecular chains and second whether the influence of crystallinity and orientation can be simply understood. ² Use of a company and/or product named by the De partment does not imply approval or recommendation of the product to the exclusion of others which may also be suitable.