Preparation And Properties Of Poly (Vinyl Alcohol) Fibers Strengthened By One-dimensional Nanomaterials

In recent years, poly (vinyl alcohol)(PVA) fibers with high performance areresearch hotspots. They are widely used in industry, agriculture, fisheries and so on. Oneimportant way to improve the strength of normal fibers is to composite withnanomaterials. Compared to nanoparticles, one dimensional nanomaterials are moreconducive to improve the performance of fibers according to the characteristics of fibermaterials. In this thesis, PVA/MWCNTs and PVA/SNW composite fibers were producedby gel spinning, in which MWCNTs and SNW were used as reinforcements. Structuresand properties of composite fibers had been studied. The corresponding details andconclusions as follows:1. MWCNTs were modified by aqua regia and tea polyphenols, respectively. Thedispersions were characterized by transmission electron microscope (TEM),Ultraviolet-visible (UV-vis) spectrometer and polarizing microscope. Teapolyphenols were not damage the conjugated structure of the MWCNTs sidewalls,and MWCNTs can disperse homogeneously.2. PVA/MWCNTs composite fibers were prepared by gel spinning, and theirmechanicalproperties and appearances were also investigated. It was found that byintroduction of MWCNTs, the interfacial interactions existed between thecomponents of PVA composite fibers, and the appearances of both pure PVA fiberand the composite fiber are smooth and homogenous. And the strength of thecomposite fibers was significantly increased compared with pure PVA fibers, coupledwith a decrease of elongation at break.3. The as-spun gel fibers were drawn at different ratios in a stretching apparatus and thestructure of drawn fibers were characterized by Raman spectra and Fourier transforminfrared spectroscopy (FT-IR). The glass transition behavior, melt behavior and thermal degradation behavior of PVA/MWCNTs composite drawn fibers were alsocharacterized by Differential scanning calorimetry (DSC) and thermogravimetricanalysis (TG). Effects of draw ratio on the properties of fibers, the mechanicalproperties and appearance of the drawn fibers were also disc ussed. It was found thatthe draw ratio has important effect on the strength of fibers, and the tensile strengthof the composite fibers increases from247to643MPa with increasing the amount ofMWCNTs loadings from0to0.6wt%. It was considered that these factors like gooddispersity of MWCNTs in the matrix, interfacial interactions between PVA matrixand MWCNTs, and nucleating agent MWCNTs acted, can increase the stiffeningproperties of PVA composite fibers. But the thermal stability of composite fiber waspoor comparing with pure PVA fibers, indicating TP decomposed in advance.4. Silver nanowires (SNW) were prepared via hydro-thermal method, and thePVA/SNW composite fibers were also fabricated by gel spinning. The mechanicaland morphology and thermal degradation behavior of the fibers were investigated.The mechanical properties showed that SNW can’t meet the target of reinforcingPVA/SNW composite fibers. After adding SNW, the strength of PVA/SNWcomposite fibers increased in a certain range, but the strength was still lower thanthat of PVA, which was resulted from the simple mechanical mixing between PVAand SNW. On the other side, SNW can improve the thermal properties of compositefibers, and the appearances of PVA/SNW fibers are smooth as those of PVA fibers.