Grafted hybrid latexes with 2-hydroxyethyl acrylate (HEA) molar ratios ranging from 0 to 0.3 were prepared and the ultimate strength, modulus, toughness, and elongation at break were evaluated as a function of HEA content. In addition, thermal analysis techniques, such as dynamic mechanical analysis, differential scanning calorimetry, and thermogravimetric analysis were used to characterize the latexes. The waterborne polyurethane (PU) / hybrid latexes were synthesized by the emulsion polymerization of vinyl monomers (styrene and butyl acrylate) in the presence of castor oil-based waterborne polyurethane dispersion using potassium persulfate as an initiator. The waterborne PU dispersion was synthesized by polyaddition reaction of 1,6-hexamethylenediisocyanate (HDI) with castor oil and dimethylolpropionic acid (DMPA). After allowing the PU reaction to progress, HEA was added to the reaction mixture to introduce graft sites for future free-radical polymerization with vinyl monomers.
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