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A Study on the Relationship Between the Crystal Structure and Hard Elasticity of PVDF Fibers
Author(s) -
Du ChunHui,
Zhu BaoKu,
Xu YouYi
Publication year - 2005
Publication title -
macromolecular materials and engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.913
H-Index - 96
eISSN - 1439-2054
pISSN - 1438-7492
DOI - 10.1002/mame.200400327
Subject(s) - materials science , lamellar structure , composite material , scanning electron microscope , annealing (glass) , elasticity (physics) , elastic modulus , modulus , synthetic fiber , spinning , fiber
Summary: Poly(vinylidene fluoride) (PVDF) fibers were prepared by melt‐spinning process. The crystal structure of annealed PVDF fibers was characterized by wide‐ and small‐angle X‐ray diffraction (WAXD and SAXD) and scanning electron microscopy (SEM). Crystalline reflections of c ‐axis orientation of annealed PVDF fibers were illustrated by WAXD pattern. The stacked lamellar structure aligned in the direction normal to the fiber axis was found in SAXD pattern and the d ‐spacing of the lamellae was 13.4 nm. Such lamellar structure was supported by SEM micrographs as well. The elastic recovery of annealed PVDF fibers was above 80% from 50% extension, which was much higher than that of unannealed fibers on the first cycle. The initial elastic modulus of annealed fibers reached to a value of 3.5 GPa. The morphological and mechanical properties, all indicated that the annealed PVDF fibers had the characteristic of hard elasticity. A typical stress‐strain curve at a very low strain rate indicated the deformation of crystal lamellae in the fibers and a suggested structural deformation mechanism detailed the characteristics of hard elasticity.Cyclic loading to 50% extension of annealed PVDF fibers.