Davood Rasouli; Hossein Yousefi; Mahdi Mashkour
Abstract
In this research, the effect of using nano-zinc oxide (nano-ZnO) as a UV absorbent on the weathering resistance of wood- polypropylene composite was investigated. For this purpose, composite samples containing 0, 1, 2 and 3% nano-ZnO were manufactured using an internal mixer and a laboratory press. ...
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In this research, the effect of using nano-zinc oxide (nano-ZnO) as a UV absorbent on the weathering resistance of wood- polypropylene composite was investigated. For this purpose, composite samples containing 0, 1, 2 and 3% nano-ZnO were manufactured using an internal mixer and a laboratory press. The prepared specimens were exposed to artificial weathering for 1480 hrs (in the periods of 0 ,480, 960 and 1480 hrs). The weathering degradation of specimens was monitored by tensile strength, hardness, colorimetry, Fourier transform infrared spectroscopy (FTIR), and, stereomicroscope tests. Results showed that weathering caused color changes, tensile strength and hardness loss, physical and chemical degradation on the surface of the samples. The use of nano-ZnO partially prevented tensile strength and hardness loss of samples as well as their surface degradation. In general, the use of 2% nano ZnO has been a better performance against weathering than other values.
Afsaneh Topa; Atamalek Ghorbanzadeh; Davood Efhamisisi
Abstract
The plasma has different effects on the surface wettability of wood, depending on the treatment conditions and the type of gas used. The hdrocarbon gases usually destroy hydrophilic groups on the surface of wood and cause hydrophobicity by creating microscopic rough structures. In this study, glide plasma ...
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The plasma has different effects on the surface wettability of wood, depending on the treatment conditions and the type of gas used. The hdrocarbon gases usually destroy hydrophilic groups on the surface of wood and cause hydrophobicity by creating microscopic rough structures. In this study, glide plasma treatment with methane was used to hydrophilize the surface of the wood and create weathering resistanc. The poplar wood (Populus deltoides) were exposed to glide plasma under various laboratory conditions such as time of exposure, voltage, frequency, distance between electrodes as well as flow of inlet gas and outlet gas with methane inside a reactor. Then the surface properties of wood were studied using scanning electron microscope (SEM), measurement of water drop contact angle, ATR‐FTIR spectroscopy, roughness survey, and colorimetry. The specimens were then subjected to the accelerated weathering using the Gardner weathering wheel and their properties were checked again. The SEM images showed that the plasma creates a warty layer on the surface of the wood which could be due to the deposition of new materials or the physical effects of plasma (surface etching). The plasma treatment significantly increased the contact angle of the water droplet on the surface of the treated samples. The treated samples had a higher surface roughness than the control samples. The surface of treated samples was generally darker than the control. After exposure to the accelerated weathering, the effect of treatments on surface hydrophobicity was largely lost. The treated samples had less roughness changes than the control after exposure to the weathering, and also their dark color changed to silver-gray. The use of glide plasma with methane gas showed the great potential for creating hydrophobic surfaces on the wood, but it did not last long and lost its effectiveness due to weathering.
Management and Economics wood
Hadi gholamian; Asghar Tarmian; Ali Abdulkhani
Abstract
In present study, the adhesion strength of polyurethane and alkyd coatings on the poplar wood (Populus nigra) was improved by nano-silane coating using sol-gel method for outdoor application. For this purpose, the boards with dimensions of 15 × 10 × 2 mm were prepared according to EN 927-5. ...
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In present study, the adhesion strength of polyurethane and alkyd coatings on the poplar wood (Populus nigra) was improved by nano-silane coating using sol-gel method for outdoor application. For this purpose, the boards with dimensions of 15 × 10 × 2 mm were prepared according to EN 927-5. The surfaces of wood specimens were modified with Tetraethoxysilane (T) sol-gel material and then, solvent-borne alkyd (AS) and solvent-borne polyurethane (PS) coatings were applied. The coated samples were placed outdoor on a platform with a slope close to Karaj latitude (36̊) for 8 months according to ISO 877 standard. In order to characterize the quality of the coatings, colorimetric, tensile adhesion (Pull off), scratch adhesion (Cross cut) and ATR-FTIR tests were performed before and after weathering. The ATR-FTIR analysis demonstrated that the wood surface was covered with silicon oxides (SiO2) attached to hydrocarbon chains. As a result of surface wood modification by sol-gel, the color and adhesion strength of polyurethane and alkyd coatings were less affected by weathering. The highest tensile and scratch adhesions were found for the combined sol-gel and polyurethane coatings.
Management and Economics wood
abdollah zamnai; Mohammad reza Mastari farahani
Abstract
In this research, the effect of oil heat-treated on the outdoor performance of coatings namely, transparent resin stain, alkydi paint, semi- transparent cellulosic stian, acrylic paint coated on eastern cotton wood was investigated. For this purpose, sound specimens with the dimensions of 50×50×2 ...
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In this research, the effect of oil heat-treated on the outdoor performance of coatings namely, transparent resin stain, alkydi paint, semi- transparent cellulosic stian, acrylic paint coated on eastern cotton wood was investigated. For this purpose, sound specimens with the dimensions of 50×50×2 mm (Longitudinal × tangential × radial) were prepared from sapwood. Test samples were treated with canola oil at temperatures of 180, 200 and 220 ° C for 4 hours. The coatings were the wet film thickness of 150µm were applied on the specimens using an applicator. The coating adhesion was measured according to ASTM D 4541 standard, and the color characteristics of the coating were measured according to ASTM D 2244 before and after a natural weathering for 180 days. The statistical analysis of the color change data showed that the effect of the oil heat-treatment on the color change depended on coating type. The statistical analysis of the adhesion strength data showed that the adhesion strength depended on the combination of weathering, oil heat-treatment and coating type.
Hamed Matini behzad; Asghar Taremian
Abstract
Poplar wood flour was spray treated with two preservative materials, (Thiabendazole or Carbamate derivatives (IPBC) with concentration of 0.9%) and then the wood/polyethylene composite samples with the composition of 60% wood, 38% polyethylene and 2% coupling agent were manufactured. The treated composite ...
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Poplar wood flour was spray treated with two preservative materials, (Thiabendazole or Carbamate derivatives (IPBC) with concentration of 0.9%) and then the wood/polyethylene composite samples with the composition of 60% wood, 38% polyethylene and 2% coupling agent were manufactured. The treated composite and control samples were exposed to weathering for 5 months using ASTM D1435 standard test method and the structural changes of the samples were analyzed using SEM microscopy. The roughness of WPCs was measured by roughness measuring device (Miyutoyo SJ 201P) before and after weathering. The SEM images showed that the highest surface changes due to weathering occurred in untreated samples. Both preservatives improved the weathering resistance of treated WPC. The differences in the roughness values root mean square roughness (Rq), mean peak-to-valley height (Rz) and average roughness (Ra) before and after weathering were measured as 7.93, 38 and 4.88µm for control samples, 1.65, 21.7 and 42.2 µm for Thiabendazole-treated and 1.2, 1.5 and 0.79 µm for IPBC-treated samples, respectively. Both preservative materials significantly improved the weathering resistance of WPCs.
Neda Moradpour; Mohammad reza Mastari frahani; Alireza Shakeri
Abstract
To investigate the effect of acetylation and antioxidant separately and together on discoloration and contact angle wood plastic composite due to weathering , composite s were made using popular wood flour and high density polyethylene . the sample were exposed to natural weathering for 6 ...
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To investigate the effect of acetylation and antioxidant separately and together on discoloration and contact angle wood plastic composite due to weathering , composite s were made using popular wood flour and high density polyethylene . the sample were exposed to natural weathering for 6 months.
The results have shown that acetylation can relatively reduce the discoloration of weathered sample treatment than control sample.the antioxidant does not have any influence on color change but it seems that antioxidant could prevent partly destruction of plastic .
It should be mention acetylating increased the surface contact angle befor weathering. But it could not protect the sample surface after the exposure period. So that was zero after weathering.
