A series of waterborne polyurethanes (WBPU) containing different amount of 2,2-bis(hydroxymethyl) propionic acid (DMPA) were synthesized using prepolymer mixing process. Relationships between the DMPA content and physical, mechanical, and thermal properties as well as adhesive behavior at different condition were investigated. Stable aqueous dispersions of WBPU were obtained when the DMPA content was more than 10 mol %. At higher DMPA content, the particle size of the WBPU dispersion was lower but the viscosity of the dispersion was higher. Water swelling and tensile strength of the films increased with increasing of DMPA content. The optimum adhesive strength of WBPU adhesives was found to be depended on the DMPA content, pressing temperature, and pressure on adhesion process. The adhesive strength of WBPU adhesives increased with increasing DMPA content. The optimum pressing temperature decreased with increasing DMPA content. The adhesive strength of WBPU adhesives increased with increasing pressure up to 15 kg f/cm 2 and then leveled off. The optimum pressing temperature of WBPU adhesives samples containing 24.02, 22.05, and 17.05 mol % DMPA was about 100, 120, and 1408C, respectively.
A polyurethane (PU) is a multifunctional polymer prepared by using more than two types of monomers. The unique properties of PU come from monomers, thus broadening the applicability of PU in many different sectors. The properties can be further improved by using many nanoparticles. Different metal oxides as nanoparticles are also widely used in PU materials. ZnO is a widely used inorganic metal oxide nanoparticle for improving polymer properties. In this review article, the techniques to prepare a PU/ZnO composite are reviewed; the key protective properties, such as adhesive strength and self-healing, and applications of PU/ZnO composites are also highlighted. This review also highlights the PU/ZnO composite’s current challenges and future prospects, which will help to broaden the composite practical application by preparing environmentally friendly composites.
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