PVA fibers with high strength and high modulus are very attractive in many potential applications. However, there is a difficulty when enhancing the strength and modulus of PVA fibers. To overcome this difficulty, here we report a method to enhance the strength and modulus of PVA fibers by synthesis of high polymerization degree (DP) and high syndiotacticity diad content (S-diad) PVA polymers with vinyl acetate (VAc)/ vinyl propionate (VPa) as monomers via non-emulsifier emulsion polymerization. The synthesized PVA polymers with different mass ratio of VAc/VPa were characterized by fourier transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance (¹H-NMR) and gel permeation chromatography (GPC), it demonstrated that the ratio of VPa monomer has a significant effect on the DP and S-diad of PVA polymers. In addition, a series of PVA fibers have been fabricated using the synthesized polymers by wet spinning method, and the mechanical and thermal properties of PVA fibers have been investigated by tensile tester, differential scanning calorimeter (DSC), thermogravimetric analyzer (TGA), X-ray diffractometer (XRD) and field emission scanning electron microscope (FE-SEM), and it found that there is a substantial increase in strength and modulus of PVA fibers with the increase of DP and S-diad of PVA polymer. However, too high DP and S-diad of PVA polymers had an opposite effect on the spinning fluid, spinnability and properties of PVA fibers.

具有高强度和高模量的 PVA 纤维在许多潜在应用中非常有吸引力。然而，在提高PVA纤维的强度和模量方面存在困难。为了克服这个困难，我们在这里报告了一种通过合成高聚合度 (DP) 和高间同立构二元组含量 (S-diad) PVA 聚合物与醋酸乙烯酯 (VAc)/丙酸乙烯酯来提高 PVA 纤维强度和模量的方法。 VPa) 作为单体通过非乳化剂乳液聚合。通过傅里叶变换红外光谱（FT-IR）、质子核磁共振（¹H-NMR) 和凝胶渗透色谱 (GPC)，表明 VPa 单体的比例对 PVA 聚合物的 DP 和 S-二单元组有显着影响。此外，采用湿法纺丝法制备了一系列PVA纤维，并通过拉伸试验机、差示扫描量热仪（DSC）、热重分析仪（TGA）、X射线衍射仪（XRD）和场发射扫描电子显微镜（FE-SEM），发现随着PVA聚合物DP和S-diad的增加，PVA纤维的强度和模量有显着增加。然而，过高的 DP 和 S-二重体对 PVA 纤维的纺丝液、可纺性和性能有相反的影响。