PROPERTIES OF HIGH-DENSITY FIBERBOARDS BONDED WITH UREA-FORMALDEHYDE AND PHENOL-FORMALDEHYDE RESINS

Abstract

Urea-formaldehyde (UF) resins are the most common type of resins used in the production of wood-based panels. Despite their numerous advantages, the main drawbacks of these thermosetting aminoplastic resins are the deteriorated water resistance, emission of hazardous volatice organic compounds, and to a lesser extent, the reduced strength. Hence, for producing wood-based panels with increased quality, a modification or partial replacement of UF resins should be performed. There are many previous studies on the improvement of UF resins with melamine-formaldehyde (MF) resins. The partial replacement of UF resins with phenol-formaldehyde (PF) resins has been studied to a lesser extent. The aim of this research work was to investigate the effects of replacing the UF resin with PF resins on the properties of high-density fiberboards (HDF). The panels were produced at a press factor of 15 s.mm-1 and a pressing temperature of 220 °C. The resin content in fiberboards was 6%, based on the dry weight of fibres. A complete replacement of UF with PF resin was performed with an increment of 1%. It was found that at 50% content of PF resin in the adhesive system, the panels meet the strictest requirements for load-bearing applications and use in humid conditions. For achieving further improvement of fiberboard properties, the PF resin content should be increased to 83.3%.