Deniz Aydemir

THE DENSITY, COMPRESSION STRENGTH AND SURFACE HARDNESS OF HEAT TREATED HORNBEAM (Carpinus betulus ) WOOD

The heat treatment of wood is an environment-friendly method for wood preservation. The heat treatment process only uses steam and heat, and no chemicals or agents are applied to the material during the process. Tests have shown no harmful emissions are apparent when working with the material. This process improves wood’s resistance to decay and its dimensional stability. In this study, the density, compression strength and hardness of heat treated hornbeam (Carpinus betulus L.) wood were investigated. Wood specimens that had been conditioned at 65% relative humidity and 20 oC were subjected to heat treatment at 170, 190, and 210 oC for 4, 8, and 12 hrs. After heat treatment, compression strength and hardness were determined according to TS 2595 and TS 2479. The results showed that the decreases of compression strength and hardness were related to the extent of density loss. Both compression strength and hardness decreased with the increasing temperatures and durations of the heat treatment. While the maximum density loss observed was 16.12% at 210 oC and 12 hour, at these heat-treatment conditions, the compression strength approximately decreased 30% and hardness values in tangential, radial, and longitudinal directions approximately decreased by 55%, 54%, and 38%, respectively. Hence, it was concluded that there might be a relationship between changes of these wood properties.

Some Physical Properties of Heat-Treated Paulownia (Paulownia elongata) Wood

The aim of this study was to determine the changes in physical properties of Paulownia (Paulownia elongata) wood, a fast-growing species, during heat treatment at three different temperatures (160, 180, and 200°C) and durations (3, 5, and 7 h). After heat treatment, changes in swelling, density, color, and equilibrium moisture content at 35, 65, and 85% RH were investigated. The results indicated that the minimum and maximum decrease swelling ratios were 6–46% for tangential, 4–32% for radial, and 12–64% for longitudinal. The equilibrium moisture contents were 1–26% for 35% RH, 1–33% for 65% RH, and 1–38% for 85 RH, respectively; the density of air-dried and oven-dried samples decreased by 1–16% and 1.5–15%, respectively, and color changes values (L*) were 10–40%.

Some Physical Properties of Heat-Treated Hornbeam (Carpinus betulus L.) Wood

Thermal treatment of wood alters its structure due to degradation of wood polymers (cellulose, hemicellulose, and lignin), so the physical properties of wood are either improved or worsen. In this study, the effect of thermal treatment on density, equilibrium moisture content (EMC), and color of hornbeam wood was investigated. The color and density (air-dry and oven-dry density) were determined for the control and heat-treated samples, as well as their equilibrium moisture content at relative humidities of 35, 50, 65, 80, and 95%. The data showed that thermal treatment resulted mainly in darkening of the wood and the reduction of its density and EMC. It was found that the treatment temperature had a much more significant impact on color changes than the duration of the treatment. Generally, heat-treated wood color becomes darker than nontreated wood, so it can be used as decorative material. Because the EMC is lower, the heat-treated wood can be used in saunas and pool sides. Also, heat-treated wood can be used in outdoor applications because of lower density.

The Effect of Heat Treatment on Some Mechanical Properties and Color Changes of Uludag Fir Wood

In this study, the effects of heat treatment on color, mass loss, compression strength, and hardness of Uludag fir (Abies bornmulleriana Mattf.) were investigated. Wood specimens conditioned at a relative humidity of 65% and a temperature of 20°C were subjected to heat treatment at 170, 190, and 210°C for 4, 8, and 12 h. After heat treatment, compression strength and hardness were determined according to TS 2595 and TS 2479. Color changes were determined according to DIN5033. The results showed that compression strength and hardness of Uludag fir wood decreased to varying extents in relation to intensity of treatment, whereas mass loss increased. We determined that treatment temperature had a more significant effect on color changes than did treatment time. The color of the wood became darker at the higher treatment temperatures.

Thermal Analysis of Micro- and Nano-Lignocellulosic Reinforced Styrene Maleic Anhydride Composite Foams

The aim of this study was to measure the thermal properties of foamed nano/macro filler–reinforced styrene maleic anhydride (SMA) composites. SMA (66%) as a polymer matrix (10% maleic anhydride content) and various fillers including wood flour, starch, α-cellulose, microcrystalline cellulose and cellulose nanofibrils as reinforcing agents (30%) and lubricant (4%) were used to manufacture the composites in a twin-screw extruder. According to the thermogravimetric analysis (TGA) results, thermal degradation of all the foamed composites was found to be lower than that of SMA composites. The storage modulus values were negatively affected with a second time foaming (reprocessing [recycling] the initially processed composites a second time), as were loss modulus and Tg. As a result, second-time-foamed composite modulus values were lower than those of the foamed composites. According to the melt flow index (MFI) results, viscosity of the SMA was found to increase with the addition of fillers.

Biocomposites from polyhydroxybutyrate and bio-fillers by solvent casting method

Biocomposites from polyhydroxybutyrate (PHB) and some bio-fillers such as lignin (L), alpha cellulose (AC) and cellulose nanofibrils (CNFs) were prepared to investigate the effect of the bio-fillers on the properties of PHB by a solvent casting method. The thermal properties by thermogravimetry analysis (TGA–DTG and DTA) and differential scanning calorimetry (DSC) were determined; morphological characterization by scanning electron microscopy (SEM) and structural analysis by X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) of the biocomposites were performed. TGA curves showed that the highest values for T10%, T50% of the biocomposites were 278.2∘C for PHB+2%AC and 291.7∘C for PHB+2%CNFs; however, the best value for T75% was obtained as 381.5∘C for PHB+2%L. According to DTG curves, the best results were found for PHB+0.5%L and PHB+0.5%CNFs. DTA showed an increase in temperature of maximum degradation with loading of lignin and CNFs. The addition of bio-fillers increases Tc and Tm for both first cooling/heating and second cooling/heating. Tc and Tm values for first cooling/healing were found to be lower as compared with second cooling/healing. Furthermore, the addition of bio-fillers acts as a nucleating agent in PHB and SEM pictures showed the porous structure in all biocomposites. SEM images revealed uniform distribution of the reinforcing particles in the polymer at low loadings (0.5 wt%), while higher loadings (2 wt%) of L and CNFs contributed to easy aggregation within the PHB matrix. In XRD studies, PHB in the range 5–55∘ shows 6 main peaks. XRD patterns of the PHB biocomposites revealed 3 main peaks at 13.57∘, 16.87∘ and 22.1∘, and the other peaks disappeared in the patterns. The largest and lowest values of Xc were found for PHB+2%AC and PHB+2%CNFs, respectively.

Influence of Micro- and Nanonatural Fillers on Mechanical and Physical Properties of Foamed SMA Composites

This study is to investigate the reinforcing effects of fillers on mechanical and physical properties of foamed styrene-maleic anhydride (SMA) composites. According to the results, the best foaming was determined for starch reinforced SMA composite. The best result of expansion ratio was found as 22.75% to SMA/starch composites. Stereo light microscopy results demonstrated that the foamed cell distribution is heterogeneous and composed of two sections. The minimum density was found as 0.64 g/cm3 for foamed SMA/starch composites. Mechanical properties of all foamed composites were found to be low as compared to neat SMA composite.

Morphological characterization of foamed natural filler-reinforced styrene maleic anhydride (SMA) composites

The aim of this study is to investigate the foaming of styrene maleic anhydride (SMA) matrix composites with a physical foaming agent, created during the reactive extrusion of natural fillers and SMA. The effect of lubricant on the foaming of SMA composites was also investigated. Whether particle’s crystallinity and hydroxyl number had any effect on cell size and cell density was also studied. The results showed that the greatest cell size and expansion occurred in the starch reinforced SMA composite which also exhibited the highest hydroxyl number and water by-product from reactive extrusion. Whereas microcrystalline cellulose-SMA composite exhibited the least cell number and expansion after extrusion because of the high crystallinity of MCC and the low hydroxyl number. Scanning electron microscopy results revealed that the cell distribution in foamed samples was heterogeneous and cell density increased from the core to skin layer. The results showed that hydroxyl number has an important effect on foaming and cell nucleation of the composites, and cell properties changed with filler’s percentage crystallinity.

The Impacts of Heat Treatment on Lap Joint Shear Strength of Black Pine Wood

This study was conducted to determine the impacts of heat treatment on lap shear strength, density, and mass loss of black pine wood. In the study, black pine wood boards bonded with polyurethane were subjected to temperatures of 160, 180, and 200°C for durations of 2 and 6 hours. Specimens having two layers were prepared from untreated and treated wood for mechanical testing of bond lines. Data were analyzed using variance analysis and Tukeys test to determine the impacts of changes in density and mass of heat-treated black pine wood on lap shear strength. The results indicated that the lap shear strength of black pine wood decreased as the intensity of heat treatment increased. The results also indicated that the minimum and maximum percentage decreases of lap shear strength were approximately 27% for 160°C and 2 hours and 78% for 200°C and 6 hours.

Nanoboron nitride-filled heat-treated wood polymer nanocomposites: Comparison of different multicriteria decision-making models to predict optimum properties of the nanocomposites:

The aim of this study is to investigate the effects of nanoboron nitride on the physical, mechanical, morphological and thermal properties of heat-treated wood high-density polyethylene composites. Three different multicriteria decision-making models such as the technique for order preference by similarity to ideal solutions, multi-attribute utility theory and compromise programming were used to predict the nanocomposites having optimum properties. High-density polyethylene as a matrix, heat-treated wood (30%) as a reinforcement filler and nanoboron nitride (0.5%, 1% and 2%) for improving the thermal stability were used; the composites prepared were grounded in a single-screw extruder, and the test samples were prepared with injection molding. According to the results, both testing and multicriteria decision-making models showed that heat-treated wood polymer nanocomposites with 2% nanoboron nitride have the optimum properties. Multicriteria decision-making methods are thought to be useful tools for materials having the optimal properties. It can be said that this study will be a guide for future material selection studies.