| Polyacrylonitrile(PAN)/hydroxyapatite composite adsorption fibers and hydrolyzed polyacrylonitrile(HPAN)/hydroxyapatite(HAp) composite adsorption fibers are prepared via wet spinning at the different coagulation bath of N,N’-dimethyl formamide(DMF) solution/water mixed, dimethyl sulfoxide(DMSO)/water mixed solution, sodium hydroxide aqueous solution(NaOH aq.)/DMSO mixed solution. The composite adsorption fibers are characterized by fourier transform infrared spectroscopy(FTIR), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The effects of HAp content, coagulation composition coagulation,temperature, roller draw ratio, draw times in the second boiling water bath and etc. on tensile strength and adsorption capacity of composite adsorption fibers are studied. The optimal process of composite adsorption fibers is analyzed using orthogonal method.The core-shell and porous structure are seen in SEM images. HAp is well dispersed in composite adsorption fibers. The peaks of PAN and HAp and the change of PAN peaks after hydrolysis are found from FTIR curves. The appearance of-CONH2and-COOH functional groups after PAN hydrolysis enhances the adsorption amount of HPAN/HAp composite adsorption fibers. It can be suggested that the crystallization of PAN is less affected by nanosize HAp from XRD cuerves. Moreover, mechanical dispersion can influence the crystallinity and crystal size of HAp particles.The effects of HAp content, HAp dispersity and coagulation conditions on the tentile strength and adsorption capacity of composite adsorption fibers are discussed. With the increment of HAp content, the tensile strength of composite adsorption fibers decreases and the adsorption capacity increases. Nanodispersed HAp is more greatly beneficial to exertion of HAp adsorption amount than microdispersed HAp. Due to fast double diffusion and formation of a loose porous structure, the tensile strength and adsorption amount of PAN/HAp composite adsorption fibers decrease with higher non-solvent ratios of coagulation bath. With the increasing of coagulation bath temperature, the greater the diffusion coefficient and the higer diffusion speed are, leading to lower tensile strength and adsorption capacity of PAN/HAp composite adsorption fibers with rigid shell region. However, the tensile strength of HPAN/HAp composite adsorption fibers increases and then decreases, while the adsorption capacity changes complicatedly. As the roller draw ratio increases, composite adsorption fibers can rearrange to obtain more regular compact structure, so that the tensile strength and adsorption capacity of PAN/HAp composite adsorption fibers increase. Unfortunately, the adsorption capacity of HPAN/HAp composite adsorption fibers increases and then decreases. The increament of draw times in the second boiling water can relax the structure of PAN macromolecules and improve PAN axial orientation of PAN/HAp composite adsorption fibers. Therefore, the tensile strength and adsorption capacity of composite adsorption fibers are enhanced. With the elongation of hydrolyzed time, the tensile strength of HPAN/HAp composite adsorption fibers decreases, while the adsorption amount decreases, following with little decrement. The enhancement of alkali concentration in coagulation bath results in decreased tensile strength and increased adsorption capacity of HPAN/HAp composite adsorption fibers. |
