Water-borne polyurethane dispersions(PUDs) are widely used for applications such as adhesives and coatings of various materials, e.g., textiles, metals, plastics, and wood. Increasing concern for health, safety, and the environment has driven many researchers to prepare water-borne PUDs with various...
Water-borne polyurethane dispersions(PUDs) are widely used for applications such as adhesives and coatings of various materials, e.g., textiles, metals, plastics, and wood. Increasing concern for health, safety, and the environment has driven many researchers to prepare water-borne PUDs with various compositions and architectures, which are expected to exhibit almost the same performances as conventional solvent-borne systems. One of the recent methods, which can modify physical properties of PUDs, are combination with acrylic monomer. However, blending of a polyacrylic dispersion with PUDs often lead to films of lower quality, which is attributed to a low compatibility of both components. Therefore, the formation of hybrid particles where each particle contains both polymers leads to a better mixing of both components. In this research, aqueous PU-polyacrylate hybrid latex particles were successfully prepared through miniemulsion polymerization process of PU solutions in acrylic monomers. This process provided a method to synthesize nano-sized hybrid latex particles by combination of polyaddition and radical polymerization in an one-pot procedure. The PU was formed from isophorone diisocyanate and polypropylene glycol (Mn = 2000). The weight ratio between PU and butyl acrylate (BA) components was varied to obtain different hybrid latexes, and the minieulsions were polymerized using potassium sulfate as initiator. Likewise, monomers of methyl methacrylate (MMA) and BA were used in various ratios. The influences of several factors, such as ratio of components (PU and acrylate) on the molecular weight and particle size, have been studied. The thermomechanical properties, water resistance and hardness were also studied with PU/Acrylate hybrid films. Particle size of the hybrid latexes depends on many variables in the system, such as the initial viscosity of the PU, hydrophilic property of acryl monomer, and their solubility. In the case of hybrid latexes films, the glass transition temperature (Tg) of MMA/BA copolymer increased by increasing the content of MMA. In other words, Tg of copolymer varies with the higher mole fraction of MMA with respect to BA in the copolymer. Water resistance of the resulting hybrids increased with increasing the PU content as well as with decreasing MMA content. In contrast to the water resistance, decreasing the hybrids became harder with decreasing PU and increasing MMA contents. On overall, by controlling the composition of both PU to acrylic and MMA to BA ratio, water resistance, and mechanical properties of the resulting PU-polyacrylate hybrid latexes could be controlled with required properties.
Water-borne polyurethane dispersions(PUDs) are widely used for applications such as adhesives and coatings of various materials, e.g., textiles, metals, plastics, and wood. Increasing concern for health, safety, and the environment has driven many researchers to prepare water-borne PUDs with various compositions and architectures, which are expected to exhibit almost the same performances as conventional solvent-borne systems. One of the recent methods, which can modify physical properties of PUDs, are combination with acrylic monomer. However, blending of a polyacrylic dispersion with PUDs often lead to films of lower quality, which is attributed to a low compatibility of both components. Therefore, the formation of hybrid particles where each particle contains both polymers leads to a better mixing of both components. In this research, aqueous PU-polyacrylate hybrid latex particles were successfully prepared through miniemulsion polymerization process of PU solutions in acrylic monomers. This process provided a method to synthesize nano-sized hybrid latex particles by combination of polyaddition and radical polymerization in an one-pot procedure. The PU was formed from isophorone diisocyanate and polypropylene glycol (Mn = 2000). The weight ratio between PU and butyl acrylate (BA) components was varied to obtain different hybrid latexes, and the minieulsions were polymerized using potassium sulfate as initiator. Likewise, monomers of methyl methacrylate (MMA) and BA were used in various ratios. The influences of several factors, such as ratio of components (PU and acrylate) on the molecular weight and particle size, have been studied. The thermomechanical properties, water resistance and hardness were also studied with PU/Acrylate hybrid films. Particle size of the hybrid latexes depends on many variables in the system, such as the initial viscosity of the PU, hydrophilic property of acryl monomer, and their solubility. In the case of hybrid latexes films, the glass transition temperature (Tg) of MMA/BA copolymer increased by increasing the content of MMA. In other words, Tg of copolymer varies with the higher mole fraction of MMA with respect to BA in the copolymer. Water resistance of the resulting hybrids increased with increasing the PU content as well as with decreasing MMA content. In contrast to the water resistance, decreasing the hybrids became harder with decreasing PU and increasing MMA contents. On overall, by controlling the composition of both PU to acrylic and MMA to BA ratio, water resistance, and mechanical properties of the resulting PU-polyacrylate hybrid latexes could be controlled with required properties.
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