Relationship Between Spinning Technology And Structure-Property Of Co-Polysulphonamide Fiber

Polysulphonamide (PSA) fiber as a kind of high temperature resistant material, is applied in the fields of high temperature resistance, corrosion prevention and flame resistance, for its great features. The co-polysulphonamide fiber self-developed and industrialized in China, is lack of systematic study for its structure and property in the spinning technology. The structure and property changes of co-polysulfonamide fiber were studied. And based on it, the pre-drawn fiber was heat-drawn with the designed technology to illustrate the effect on fiber’s structure and properties, for the aim to guide industry production.The co-polysulphonamide fibers during the spinning process were provided by Talon Ltd from the procedures of coagulating, coagulated-drawing, watering, drying, heat-drawn, heat-setting and oiling. The structure characteristics were studied with synchrotron small-angle X-ray scattering(SAXS) and wide-angle X-ray diffraction(WAXD) technologies. It is shown that the macromolecular morphology as-spun fiber is in amorphous state. The macro-structure was partly oriented and there is no crystallization in the fibers by coagulated-drawing. The space of macromolecular chain turned to be larger and the state stayed unchanged. The fibers formed faint polycrystalline structure with unobvious orientation after drying procedure. The crystallinity and crystalline orientation of the PSA fiber enhanced obviously during heat-drawn and heat-setting procedure, with the increase in crystalline grain sizes, and the form of lamellae structure. But the crystallinity and crystalline orientation of the PSA fiber reduced by oiling procedure with the reduce of crystalline grain sizes, and the lamellae orientation.Based on the above study, the effects by heat-drawn technology on properties and structure of co-polysulphonamide were focused on. Firstly, the pre-drawn co-polysulphonamide fiber was heat-drawn by batch operation with the multiple stages at different temperature. The properties of the fibers were characterized by Stress-strain test, DMA and TGA. It was shown that the decomposition temperature varied little while the glass transition temperature Tg increased at first and then decreased across the heat-drawn stages. The mechanical property increased when the pre-drawn fiber was heat-drawn, but reduced after the heat temperature at380"C. From the results of macro-structure analysis, it is clear that the crystalline structure and lamellae structure formed after heat-drawn above the temperature at350℃. The crystallinity, crystal orientation, crystallite size of the fibers and the long period of lamellae increased across the heat-drawn stages. Meanwhile it was found that the mechanical property had no huge difference in the fibers by four-stage and five-stage batch heat-drawn. Then, the pre-drawn co-polysulphonamide fiber was heat-drawn by continuous operation with the designed technology of three stages at different temperature varying from350to390℃, and then heated in different temperatures for2h. It was shown that the decomposition temperature varied little while the glass transition temperature Tg increased with the heat-drawn temperature. The tenacity and initial modulus increased when the pre-drawn fiber was heat-drawn and the max was up to4.65cN/dtex, although the dependence of mechanical properties on temperature was not linear. From the results of morphology and crystalline structure analysis, it is clear that the crystalline structure and the lamellae structure formed while the crystallinity, crystal orientation and crystallite size of the fibers increased with the increasing of heat-drawn temperature. It suggested that the mechanical and thermal properties of pre-drawn fiber improved by heat-drawing due to the formation of order crystalline structure but the exorbitant temperature would lead to thermal oxidation and brittleness for the fibers.