Investigation on the physical properties and internal bonding of HDF made of oxidized fiber

Abstract

Current research was conducted to investigate the physical properties and internal bonding of High-Density Fiberboard (HDF) made from oxidized fibers and different amount of glue. In order to surface modification, fiber was treated with 40% nitric acid. After fibers gluing with urea-formaldehyde (7% and 9% based on the dry weight of fibers), the boards with a density of 0.9 g/cm3 were made by hot pressing at 175°C and 4 minutes. The results of spectroscopy were confirmed the reduction of hydroxyl functional groups and the increase of the carboxylic group due to oxidation. The results of short term immersion test in water showed that in boards containing oxide-modified fibers and 9% urea-formaldehyde glue were measured the minimum water absorption and thickness swelling with mean of 78.5 and 28.65%, respectively.Spring back of modified boards containing less glue was affected by the stresses release and debonding of the wood elements that resulted in internal bonding loss