Modification of nanoclay with different methods and its application in urea-formaldehyde bonded plywood panels

Abstract

The reinforcement of pristine nanoclay (PNC) and modified nanoclay (MNC) in urea-formaldehyde (UF) resins at the alkaline stage of synthesis was investigated in this work. The modification of PNC using copper (II) chloride (CuCl2) as transition metal ions was carried by three different modification methods that were coded as Cu-MNC (25, 36), Cu-MNC (60, 6), and Cu-MNC (80, 3), respectively. The modification of PNC was characterized by X-ray diffraction, showing the increased d-spacing after the modification. The reinforcement of 5 wt% of PNC and Cu-MNC at the alkaline reaction of UF resins that were coded as UF/PNC, UF/MNC (25, 36), UF/MNC (60, 6), and UF/MNC (80, 3). The X-ray diffraction study showed that the addition of PNC and Cu-MNC into the UF resins decreased the crystallinity of resins from 48.1% to 45% for UF/PNC and 25% for all UF/MNC. The curing behavior exhibited that the activation energy of UF resins decreased with addition of PNC and Cu-MNC. The loading of PNC and Cu-MNC into UF resins improved the adhesion and reduced the formaldehyde emission of UF resins in plywood. Statistical analysis suggested that UF/MNC (80, 3) produced plywood with greater adhesion strength and lower formaldehyde emission over other modified resins.