Young's modulus of transcrystallinities in semicrystalline thermoplastic composites

Abstract
In a fiber/semicrystalline polymer system, interphasial transcrystallinities might form between the fibers and the matrix bulk that is composed of spherulites. By using an analogy method, the Young's modulus Et of transcrystallinities in their growth direction was predicted by a well‐known composite modeling theory. It is shown that Et is a function of the polymeric lamellar morphology and crystallinity. It is higher than the Young's modulus Es of the bulk spherulites and positively affects the stiffness of the materials in which the transcrystallinities are formed. The study was focused on poly(ether ether ketone) (PEEK) but with polyethylene (PE) as a comparison. Also, it is demonstrated the various possibilities of the value ET and the ratio ET/Es for different polymeric matrices depending on their lamellar moduli and the amorphous‐phase ones. © 1994 John Wiley & Sons, Inc.