Abstract:

In order to obtain poly(vinylidene fluoride) (PVDF) fibers with high tensile strength，post-treatment tests of fibers with a certain length and tension produced during the fiber drawing process were designed to explore the optimal post-treatment parameters. Thermal analysis (DSC), infrared spectrum (FTIR), X- ray diffraction (XRD) and tensile tests were carried out to analyze the crystal form structure, crystal orientation, grain size, degree of crystallinity and mechanical properties of the fibers. The results show that: α-phase crystalline could be further transformed to β-phase after the post-treatment and the content of β-phase increased from 74.6% to 88.7%. The crystallinity increased from 49.4% to 52.3%. The orientation factor increased from 0.793 2 to 0.833 4, and the tensile strength of fiber increased markedly, especially under the conditions of treating at 60°C for 3 h, the tensile strength reached to 633 MPa. Compared with untreated fiber, the tensile strength increases by 70 MPa.

Key words: tensile strength, poly(vinylidene fluoride) fiber, post-treatment, crystal transformation, crystal orientation