Preparation And Application Properties Of High-dispersion Additives For Short-cut High-strength And High-modulus PAN/PVA Fibers

The high-strength and high-modulus polyacrylonitrile fibers and formalized polyvinyl alcohol fibers have the advantages of abrasion resistance,aging resistance,corrosion resistance,etc.,and they are widely used as engineering materials for asphalt and cement concrete in civil engineering and road bridges.At present,the short-cut PAN and PVA fibers at home and abroad usually have uneven distribution,easy agglomeration and easy aggregation in the concrete matrix due to their own materials,structure and fiber surface wettability,which affect the performance of fiber reinforced concrete materials,quality and practical application.Increasing the dispersion performance of short-cut reinforcing fibers in concrete matrix is also a key technical issue for the urgent development of the domestic fiber concrete industry.In this paper,through the design and synthesis of the molecular structure of dispersing agent monomer,the formulation design and compounding of dispersing agent were studied with the synthesized monomer as the main component.Two kinds of hydrophobic/hydrophilic dispersing additives for short-cut fibers were prepared.The application of self-made dispersing additives for short-cut reinforced fibers was studied with the core of enhancing the hydrophobicity and hydrophilicity of the surface of the fibers.In this paper,modified waterborne epoxy phosphate(WPEK)was selected as the main monomer of PAN fiber dispersant to prepare PAN dispersant additives.The optimum technological conditions for WPEK synthesis are as follows:the ratio of reactant to feed n(E20):n(P2O5)=1.2:1,the epoxy value of the product is 0.057mo·100g-1,the content of monoester is 0.44%,and the content of diester is 0.56%.The PAN fiber dispersant(WPEKF)was prepared by mixing WPEK with fluorinated surfactants.The performance test showed that when the WPEKF emulsion concentration was 0.5%and the fluorine content was 0.10%,the surface tension of emulsion reached the minimum value,and the contact angle reached the maximum value of 144.38 ° on the surface of flat glass.The surface morphology and dispersibility of PAN fibers treated with WPEKF were characterized.The results showed that the contact angle between fibers and water reached 148.73 ° when the amount of dispersant was 6.0mg·g-1,showing a high hydrophobic property,thus improving the dispersion of fibers in oil-phase dispersion media.Polyoxyethylene propylene block polyether(TES-90),potassium polyoxyethylene phosphate(8102PK)and high-carbon phosphate(1618PK),were used to test their performances.The results showed that the three monomers had little difference in their performances,and each had its own advantages.The main component of PVA fiber dispersant assistant(TPEK)was synthesized by mixing the three monomers with emulsifier.PVA fiber dispersant(TPEKF)was prepared by blending TPEK with fluorinated surfactants.The performance test showed that when the TPEKF emulsion concentration was 0.5%and the fluorine content was 0.10%,the surface tension of the emulsion reached the minimum value,and the contact angle on the surface of the flat glass reached a minimum value of 28.81 °.The surface morphology and dispersibility of PVA fibers treated with TPEKF dispersant were characterized.The results showed that the hydrophilicity of the sizing PVA fibers was the strongest when the amount of TPEKF dispersant was 4.0mg·g-1.The contact angle between the fibers and water was reduced to 28.29°,which was characterized by high hydrophilicity and improved the dispersion of PVA fibers in aqueous dispersion medium.