Research On The Sizing Agents Of Pure Popan Staple Warps For Weaving

In order to develop the single yarn fabrics woven from pure staple warps of pre-oxidized polyacrylonitrile (POPAN) and to avoid the defects of POPAN filament and blend fabrics, a sizing operation was applied to pure POPAN staple yarns for improving their weavability during the production of the fabrics on modern weaving machines. The technique can be expected to solve the problems such as low tensile strength, poor abrasion resistance, excessive hairs, and hard to weave of pure staple pre-oxidized polyacrylonitrile (POPAN) warps.The sizing operation using PVA and PEO were applied to the warp for imparting essential weavability to the warps. The effects of the degrees of polymerization and alcoholysis on paste viscosity, adhesion to POPAN, and desizability were explored. The influence of PVA structure on the static contact angle of PVA paste onto the surfaces of pure POPAN fabrics was measured. In addition, the performances such as increase in tensile strength, loss in elongation, abrasion resistance, decrease in hairiness, and desizing efficiency of the sized warps were investigated for determining suitable paste concentration, size add-on, degrees of polymerization and alcoholysis of PVA. By using polyethylene oxide (PEO) as sizing agent, the effect of molecular weights on the sizing performances of pure POPAN staple warps was investigated. The relationship between PEO molecular weights and its paste viscosity, adhesion-to-fiber, film performances, desizing efficiency, and yarn properties such as the increase in tensile strength, loss in elongation, abrasion resistance, and decrease in hairiness of sized yarns was explored.The research results showed that the molecular structure has a great influence on paste performance of PVA. PVA with high degree of polymerization had stronger adhesion than PVA with low degree of polymerization. Adhesion decreased with the degrees of alcoholysis increased. PVA-1788 displayed stronger adhesion-to-POPAN, better film property, and good desizability compared to other counterpart considered. Paste concentration also influenced the performance of PVA. Pure POPAN staple sized yarns will get better performances when using PVA-1788 at 7%.Molecular weight was important index of PEO paste. Paste viscosity, adhesion-to-fiber, performances of films improved with the molecular weight increased. The properties of these sized yarns could be improved by increasing the molecular weights in the range considered. But extra large molecular weight of PEO was not convenient to size, due to high viscosity. Based on the viscosity, adhesion, desizability, film performances, and properties of sized yarn, the PEO with the molecular weights range of 1.0-1.5 ×105 can be recommended for sizing pure POPAN staple single yarns before weaving process.