UV-cured clay/based nanocomposite topcoats for wood furniture: Part I: Morphological study,water vapor transmission rate and optical clarity

The combination of UV-curing technology and nanotechnology has been applied in this study to synthetize by in situ photopolymerization method, UV-cured topcoats based on acrylate matrix reinforced (1 and 3 wt%) individually with three different types of commercial organoclays, namely Cloisite 10A (C10A), Cloisite 15A (C15A) and Cloisite 30B (C30B). The morphological study was quantitatively and qualitatively performed by X-ray diffraction (XRD) and by transmission electron microscopy (TEM) respectively. Water vapor transmission rate (WVTR) and optical clarity of these nanocomposites were also assessed. TEM images obtained for those UV-cured coatings respectively reinforced with C10A and C30B showed that the absence of diffraction peaks in XRD patterns of these samples do not mean necessarily a possible exfoliation of their layered silicate nanoparticles by acrylate matrix (AM). Indeed, according to TEM images, we believe that C30B was not dispersible in the AM; while both UV-cured nanocomposites containing C10A and C15A respectively seemed to have an intercalated morphology regardless of the clay content (1 and 3 wt%). All the organoclays used in this study have had an effect on both WVTR and optical clarity. The tortuous path created by the organoclay dispersed into the AM, by retarding the progress of water vapor through a sample, best explain the decrease of WVTR whereas the decrease of optical clarity is due to the light scattering by organoclay particles. Based on the above mentioned results, among the three different reinforcing agents used in this study, C10A appears to be the ideal organoclay for practical application.