Waterborne polyurethane is a new type of polyurethane system that uses water instead of organic solvents as a dispersing medium. It has the advantages of no pollution, safety and reliability, excellent mechanical properties, good compatibility, and easy modification.
However, polyurethane materials also suffer from poor water resistance, heat resistance, and solvent resistance due to the lack of stable cross-linking bonds.
Therefore, it is necessary to improve and optimize the various application properties of polyurethane by introducing functional monomers such as organic fluorosilicone, epoxy resin, acrylic ester, and nanomaterials.
Among them, nanomaterial modified polyurethane materials can significantly improve their mechanical properties, wear resistance, and thermal stability. Modification methods include intercalation composite method, in-situ polymerization method, blending method, etc.
Nano Silica
SiO2 has a three-dimensional network structure, with a large number of active hydroxyl groups on its surface. It can improve the comprehensive properties of the composite after being combined with polyurethane by covalent bond and van der Waals force, such as flexibility, high and low temperature resistance, aging resistance, etc. Guo et al. synthesized nano-SiO2 modified polyurethane using in-situ polymerization method. When the SiO2 content was about 2% (wt, mass fraction, the same below), the shear viscosity and peel strength of the adhesive were fundamentally improved. Compared with pure polyurethane, the high temperature resistance and tensile strength have also slightly increased.
Nano Zinc Oxide
Nano ZnO has high mechanical strength, good antibacterial and bacteriostatic properties, as well as strong ability to absorb infrared radiation and good UV shielding, making it suitable for making materials with special functions. Awad et al. used the nano positron method to incorporate ZnO fillers into polyurethane. The study found that there was an interface interaction between the nanoparticles and polyurethane. Increasing the content of nano ZnO from 0 to 5% increased the glass transition temperature (Tg) of polyurethane, which improved its thermal stability.
Nano Calcium Carbonate
The strong interaction between nano CaCO3 and the matrix significantly enhances the tensile strength of polyurethane materials. Gao et al. first modified nano-CaCO3 with oleic acid, and then prepared polyurethane/CaCO3 through in-situ polymerization. Infrared (FT-IR) testing showed that the nanoparticles were uniformly dispersed in the matrix. According to mechanical performance tests, it was found that polyurethane modified with nanoparticles has higher tensile strength than pure polyurethane.
Graphene
Graphene (G) is a layered structure bonded by SP2 hybrid orbitals, which exhibits excellent conductivity, thermal conductivity, and stability. It has high strength, good toughness, and is easy to bend. Wu et al. synthesized Ag/G/PU nanocomposites, and with the increase of Ag/G content, the thermal stability and hydrophobicity of the composite material continued to improve, and the antibacterial performance also increased accordingly.
Carbon Nanotubes
Carbon nanotubes (CNTs) are one-dimensional tubular nanomaterials connected by hexagons, and are currently one of the materials with a wide range of applications. By utilizing its high strength, conductivity, and polyurethane composite properties, the thermal stability, mechanical properties, and conductivity of the material can be improved. Wu et al. introduced CNTs through in-situ polymerization to control the growth and formation of emulsion particles, enabling CNTs to be uniformly dispersed in the polyurethane matrix. With the increasing content of CNTs, the tensile strength of the composite material has been greatly improved.
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Post time: Jan-10-2025