Umit Buyuksari

Evaluation of the physical, mechanical properties and formaldehyde emission of particleboard manufactured from waste stone pine (Pinus pinea L.) cones

The objective of this study was to investigate some physical/mechanical properties and formaldehyde emission of particleboard containing particles of waste stone pine cone at various usage ratios using urea-formaldehyde resin. Some physical (thickness swelling, water absorption), mechanical (modulus of elasticity, modulus of rupture, internal bond strength) properties and formaldehyde emission of particleboards were evaluated. The addition of cone particle improved water resistance of the panels and greatly reduced their formaldehyde emissions. However, flexural properties and internal bond strength decreased with increasing cone particle content in the panel. The cone of the stone pine can be considered as an alternative to wood material in the manufacture of particleboard used in indoor environment due to lower thickness swelling, water absorption and formaldehyde emission.

Utilization of Waste Tire Rubber in the Manufacturing of Particleboard

Utilization of waste tire rubber in the manufacture of particleboard was investigated, using the same method as that used in the wood-based panel industry. The manufacturing parameters were: a specific gravity of 0.65 and waste tire rubber content (10/90, 20/80, and 30/70 by wt% of waste tire rubber/wood particle). Two resin types, melamine/urea formaldehyde (MUF) and polyisocyanate, were used in the experiments. Average modulus of rupture values of MUF bonded particleboards with rubber crumbs were between 13–58% lower than the average of the control samples while polyisocyanate bonded particleboards were 12–51%. Water resistance of the boards improved with the increase in rubber crumb/wood particle ratio. Thickness swelling values of the MUF bonded particleboards decreased from 14–53% while polyisocyanate bonded particleboards were 9–48% as compared to control samples.

Utilization of waste tire rubber in manufacture of oriented strandboard

Some physical and mechanical properties of oriented strandboards (OSBs) containing waste tire rubber at various addition levels based on the oven-dry strand weight, using the same method as that used in the manufacture of OSB. Two resin types, phenol-formaldehyde (PF) and polyisocyanate, were used in the experiments. The manufacturing parameters were: a specific gravity of 0.65 and waste tire rubber content (10/90, 20/80 and 30/70 by wt.% of waste tire rubber/wood strand). Average internal bond values of PF-bonded OSB panels with rubber chips were between 17.6% and 48.5% lower than the average of the control samples while polyisocyanate bonded OSBs were 16.5-50.6%. However, water resistance and mechanical properties of OSBs made using polyisocyanate resin were found to comply with general-purpose OSB minimum property requirements of EN 300 Type 1 (1997) values for use in dry conditions at the lowest tire rubber loading level (10%) based on the oven-dry panel weight. The tire rubber improved water resistance of the OSB panel due to its almost hydrophobic property. Based on the findings obtained from this study, we concluded that waste tire rubber could be used for general-purpose OSB manufacturing up to 10% ratio based on the oven-dry panel weight.

Effect of Thermal Compression Treatment on the Surface Hardness, Vertical Density Propile and Thickness Swelling of Eucalyptus Wood Boards by Hot-pressing

Thermal treatment techniques are used for modifying wood and wood-based materials to improve dimen- sional stability and hygroscopicity. This study investigated the effects of press pressure and temperature on density, vertical density profile, thickness swelling and surface hardness of eucalyptus wood boards. The experimental wood boards were prepared from Turkish River Gum (Eucalyptus camaldulensis Dehn.). The surface hardness value increased with increasing press pressure in the treated groups. The application of a higher pressure at the same temperature level increased the amount of swelling of wood. It means that it is not needed for application of higher pressure to enhance the dimensional stability of wood. It is expected that it is possible to produce increased hardness, dimensional stability and durability by appli- cation of hot pressing treatment. This research showed that different press pressure and temperature values should be used to improve the performance properties of eucalyptus wood so that the end-use of the wood materials could be expanded.

Enhancement of Dimensional Stability of Biocomposites Containing Agricultural Waste by Heat-Treatment Method

The objective of this research was to enhance the dimensional stability of biocomposites containing agricultural waste using a heat-treatment method. For this aim, cotton stalk (CS) flour was treated at 150 or 180°C for 30 or 60 min in atmospheric air. The ratio of softwood fiber to heat-treated (CS) flour in the biocomposites (medium-density fiberboards, MDF) with a density of 700 kg/m3 was 75/25%. The MDF panels were made using standardized procedures that simulated industrial production at the laboratory. Heat treatment of the CS flour significantly enhanced the water resistance of the MDF panels such as thickness swelling and water absorption. An increase to 60 min of heat treatment at 150 or 180°C resulted in a further reduction of the swelling properties compared to the standard treatment (30 min). However, the mechanical properties such as modulus of rupture, modulus of elasticity, and internal bond strength declined as the temperature and time increased. This study revealed that the dimensional stability of the MDF panels incorporated with heat-treated CS flour was better than that of the panels incorporated with untreated CS flour.