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High mechanical property poly (vinyl alcohol) (PVA) fibers have attracted tremendous attentions because of their excellent mechanical properties and has a potential application in the field of building enhancement. In this article, PVA polymer with high polymerization degree (Pn) and high Syndiotacticity-diad content (S-diad) were synthesized using vinyl acetate (VAc) and vinyl pivalate (VPi) as monomers via emulsion polymerization with water as solvent, the GPC and 1H NMR were used to characterized the Pn and S-diad of PVA polymer. Then the lanthanum chloride (LaCl3) was chosen as cross-linking and the synthesized PVA polymer as raw material for dry-wet spinning, a series of PVA fibers with high strength and high modulus have been prepared. The final PVA-La fibers were characterized through a series of experiments including of FTIR, SEM, DSC, TGA, XRD and fiber tensile tester. It turned out that the Pn and S-diad of synthesized PVA polymer were 4817 ± 76 and 56.3 ± 0.7%. With the increasing of LaCl3 content, the -OH vibration absorption peak of PVA-La composite fiber gradually increased from 3462 cm-1 to 3484 cm-1; the strength, modulus, crystallinity and orientation all increased first and then decreased. Especially, the properties of PVA-La fiber exhibited an optimal LaCl3 content of 0.8 wt%, the denier was 5.4 ± 0.5 dtex, the tensile strength and highest elastic modulus of 15.19 ± 0.5 cN/dtex and 369.21 ± 9.1cN/dtex, the elongation at break was 3.72 ± 0.4%, the crystallinity was 53.9 ± 0.6%, the orientation was 95.6 ± 0.6%. [ABSTRACT FROM AUTHOR]

Different vinyl acetate (VAc) and vinyl benzoate (VBz) monomer ratios have been chosen as monomers to create high polymerization degree (Pn) and high syndiotacticity‐diad content (S‐diad) poly(vinyl alcohol) (PVA) polymers via emulsifier‐free polymerization in order to address the problem of limited mechanical capabilities of PVA fibers prepared with low Pn and low S‐diad polymer. The variations in hydrogen bonding, Pn, S‐diad, and viscosity of different PVA polymers were investigated and evaluated using Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, gel permeation chromatography, and a viscosity tester. Moreover, various PVA fibers with high strength and modulus have been manufactured using a synthetic polymer as the raw material for dry‐wet spinning. The effect of Pn and S‐diad on the mechanical and thermal characteristics of PVA fibers is evaluated using a variety of characterization techniques, such as the scanning electron microscope, differential scanning calorimetry, thermogravimetric analyzer, X‐ray diffraction, and tensile tester. As the ratio of VBz monomer increased, the results suggested that VBz may have a considerable impact on the Pn and S‐diad of PVA polymers, the OH vibration absorption peak reduced from 3491 to 3442 cm−1; the Pn increased from 2112 to 17,704; and the S‐diad rose from 51.2% to 60.1%. In addition to the fact that Pn and S‐diad significantly increased the fibers' strength and modulus, the crystallinity increased from 41.8% to 51.7%, and the orientation degree rose from 87.5% to 91.7%, as Pn and S‐diad increased; the tensile strength and highest elastic modulus increased from 9.71 ± 0.3 cN/dtex to 12.74 ± 0.5 cN/dtex (increased of 31.2%) and 264.52 ± 9.3 cN/dtex to 338.41 ± 8.6 cN/dtex (increased of 27.9%); the elongation at break decreased from 5.63 ± 0.3% to 2.92 ± 0.2%. [ABSTRACT FROM AUTHOR]

Polyvinyl alcohol (PVA) fibers were prepared using PVA with different degree of polymerization (DP) under the same wet spinning process. The effect of the DP of PVA on the structures and properties of PVA and PVA fibers were studied by using nuclear magnetic resonance hydrogen spectroscopy (1H‐NMR), Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), differential scanning calorimeter (DSC), thermo gravimetric analysis (TGA), and environmental scanning electron microscope (ESEM). The results showed that DP had little effect on the crystallinity and tacticity of PVA, but had a positive effect on melting temperature, and initial decomposition temperature of PVAs. The hot drawing ratio determined by the spinning process where the PVA fibers could be continuously collected without breaking. The drawing ratio was decreased with an increase of DP, resulting in an increase of the final fiber diameter. The PVA fibers with medium DP and medium size demonstrated high strength and high modulus, but relatively low breaking elongation. It suggested that high DP of PVA was not a guarantee of high strength and high modulus PVA fibers, but rather a primary structure factor. The fiber performance was determined by a comprehensive effect combining a variety of factors including polymer properties and spinning conditions. It provided a guideline for PVA fiber manufacture that the PVAs with different DP require different spinning processes to obtain optimal fiber performance. [ABSTRACT FROM AUTHOR]

To address the challenge of enhancing the mechanical properties of polyvinyl alcohol (PVA) fiber, constrained by the spinning process limitations, this study introduces a PVA/DMSO spinning solution. The solution, with concentrations ranging from 21.0 wt%, utilized PVA polymer (DP of 7499 and S-diad of 53.7 %) as the raw material. This approach facilitated the production of high-strength and high-modulus PVA fibers through a consistent dry-wet spinning method. The viscosity of the spinning solution was determined using a viscometer, while the PVA fibers underwent comprehensive characterization through various testing methodologies. Fourier Transform Infrared (FTIR) spectroscopy analysis revealed an initial increase followed by a decrease in the hydrogen bonding within PVA fibers as the spinning solution concentration increased. Scanning Electron Microscope (SEM) imagery indicated that the surfaces of the PVA fibers were smooth. Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), and X-Ray Diffraction (XRD) analyses demonstrated that the melting temperature, thermal decomposition temperature, and crystallinity of the PVA fibers exhibited a similar trend of initial increase and subsequent decrease with rising concentrations of the spinning solution. In addition, mechanical tester indicated that when spinning solution concentration was 22.5 wt% the PVA fibers process best mechanical property, and the breaking strength and elastic modulus reached 15.02 ± 0.5 cN/dtex and 357.12 ± 9.4 cN/dtex, respectively. [Display omitted] [ABSTRACT FROM AUTHOR]