Mehmet Akgül

The effect of heat treatment on some chemical properties and colour in Scots pine and Uludağ fir wood

Heat treatment is often applied to some wood species to improve the dimensional stability of the wood. In this study, the effects of heat treatment on the colour of Scots pine (Pinus sylvestris L.) and Uludag fir [Abies Nordmanniana (Stev.) subsp. Bornmuelleriana (Mattf.)] were examined. These species have a high potential for industrial usage and are found on large plantations in Turkey. Changes in the chemical structure of the treated wood were determined by analyzing the holocellulose and lignin content, as well as, the hot water solubility. Wood specimens obtained from Bolu, Turkey were subjected to heat treatment under atmospheric pressure at varying temperatures (120, 150, and 180°C) for varying durations (2, 6, and 10 h), then some chemical properties and colour change of the wood specimens were tested in comparison with untreated ones. The results showed that chemical properties decreased with increased treatment temperature and durations while heat treatment made the colour of the wood specimens dark.

A comparison of soda and soda-AQ pulps from cotton stalks.

In this study, cotton stalks (Gossypium hirsutum L.) were cooked using soda and soda-anthraquinone (AQ) process. Nine soda cooks were conducted by changing cooking conditions including active alkali charge and pulping time. Soda-AQ cooks were obtained by adding 0.075, 0.10, 0.15, 0.2% AQ (based on o.d stalks) to optimum soda pulping. Adding AQ to soda pulps led to the increase in regarding to pulp yield and kappa numbers. On the other hand, soda-AQ pulps made from cotton stalks showed higher mechanical properties than soda pulps. The results indicated a major increase in pulp brightness when soda pulping was modified with %0.15 AQ. Also, the results showed that better pulp and paper can be produced from cotton stalks by soda-AQ process compared to the soda process.

Wettability and surface roughness characteristics of medium density fiberboard panels from rhododendron (Rhododendron ponticum) biomass

Wettability and surface roughness properties of medium densityberboard (MDF) panels made from Rhododendron biomass were examined in this study. Rhododendron dominates the understory layer of the forests throughout the Black Sea Region in Turkey with substantial biomass potential. � is study was conducted to evaluate suitability of Rhododendronber for MDF production. For the experiments, rhododendron and commercially-manufactured-chip (Pinus sylvestris L. and Quercus robur L.) with 11% moisture content were used. � e mixing ratios of rhododendron with commercially-manufactured-chip were 100:0, 75:25, 50:50, 25:75 and 0:100 %, respectively. Commercial urea formaldehyde (UF) adhesive was used as a binder. A stylus method was employed to evaluate the surface characteristics of the samples. Roughness measurements by the stylus method were taken perpendicularly to theber. � ere was a signicant dierence (p=0.05) between surface roughness parameters (R a , R z , R q , and R y ). � e results obtained in this study revealed that all the panels have met the general purpose-use requirements of European Norm (EN). It was found that panels made with a 25/75 ratio of rhododendron to commercially-manufactured-chip had a signicantly lower contact angle (88.14 o ) than panels made with a 100/0 ratio (117.91 o ). Surface roughness measurements are based on four roughness parameters, average roughness (R a ), mean peak-to-valley height (R z ), root mean square roughness (R q ), and maximum peak-to-valley height (R y ) were considered to evaluate the surface characteristics of the panels and supported the above � ndings as the panels made with a 25/75 ratio had a slightly rougher surface with average values of 2.929 �m (R a ). From the tests performed, we conclude that increasing the rhododendron mixing portion increased surface roughness and decreased wettability. Based on these results, rhododendron biomass could be an alternative raw material for MDF manufacturing.