This study describes the effects of the addition of inorganic nanosized UV absorbers on physicomechanical
and thermal properties of an exterior commercial acrylic-based waterborne stain for wood.
Electronic microscopy and water vapor (WV) permeability measurements were performed to characterize
the free films of the acrylic stain and resulting nanocomposite coatings. An accelerated weathering
method was used to evaluate aging behavior of the coatings on wood through appearance, Tg, abrasion
resistance, adhesion strength, hardness and Young’s modulus changes. In addition to improving the protection
against UV, the doped TiO2 and silica-coated ZnO nanoparticles in powder form have improved
the abrasion resistance and barrier effect against water vapor diffusion of the acrylic stain. For most of
nanocomposite coatings,the addition of ZnO hydrophilic nanoparticles in predispersed form has resulted
in a decrease in WV permeability, while the adhesion strength and abrasion resistance of those coatings
were negatively affected. The addition of ZnO nanoparticles has decreased the Tg of the acrylic stain.
Finally, the accelerated weathering has induced an increase in Tg, hardness, Young’s modulus (stiffness)
and an increase in apparent adhesion strength and abrasion resistance of the coatings. The Tg values of
the aged nanocomposite coatings were lower than that of unmodified acrylic stain.
This study describes the effects of the addition of inorganic nanosized UV absorbers on physicomechanicaland thermal properties of an exterior commercial acrylic-based waterborne stain for wood.Electronic microscopy and water vapor (WV) permeability measurements were performed to characterizethe free films of the acrylic stain and resulting nanocomposite coatings. An accelerated weatheringmethod was used to evaluate aging behavior of the coatings on wood through appearance, Tg, abrasionresistance, adhesion strength, hardness and Young’s modulus changes. In addition to improving the protectionagainst UV, the doped TiO2 and silica-coated ZnO nanoparticles in powder form have improvedthe abrasion resistance and barrier effect against water vapor diffusion of the acrylic stain. For most ofnanocomposite coatings,the addition of ZnO hydrophilic nanoparticles in predispersed form has resultedin a decrease in WV permeability, while the adhesion strength and abrasion resistance of those coatingswere negatively affected. The addition of ZnO nanoparticles has decreased the Tg of the acrylic stain.Finally, the accelerated weathering has induced an increase in Tg, hardness, Young’s modulus (stiffness)and an increase in apparent adhesion strength and abrasion resistance of the coatings. The Tg values ofthe aged nanocomposite coatings were lower than that of unmodified acrylic stain.
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