جستجوی مقالات مرتبط با کلیدواژه "نانو رس" در نشریات گروه "جنگلداری"

Urea Formaldehyde resin is an important rein in wooden panel industries. Compared with other amino resins, this resin is cheap and colorless when it is polymerized. It is used easily since its solvent is water. But it has some disadvantageous such as its low resistance to moisture and its emission during production and service which is harmful for human health. Researchers are conducting massive investigations to substitute formaldehyde in urea formaldehyde resin with other non harmful materials. Furfural is an aldehyde chemical material which react with urea as formaldehyde do. Furfural can be obtained from crop products such as wheat straw, corn stalk and sugar cane. In this study substitution of furfural instead of formaldehyde for making urea furfural resin and improvement of resulted resin using nano clay were investigated. Furfural and urea were mixed with molar ratio of 1 to 1, 1 to 2.2 and 1 to 3.5. Lap -sheer strength test was conducted to evaluate bond strength. Beech strands were dried before gluing. Ammonium chloride was used as hardener. Strand ends were glued using urea furfural resin and assembled. After resin curing in oven, assembled were tensile loaded and tensile strength was measured. 10 samples from each urea furfural resin were prepared for tensile test and tensile sheer strength were measured. results showed that urea furfural with molar ratio of 1 to 2.2 is the best among others. This resin was selected for next step of resin preparation. Nano-clay with amount of 0.5 %, 1 % and 2 % [oven dry wight of resin] was added to urea furfural resin with molar ratio of 1 to 2.2 and resin properties such as density, solid content, viscosity, gel time and bond shear strength were measured. Spectroscopy FTIR, Imaging FESEM and XRD for study reaction of nano-clay and its distribution in the resin were conducted. Results showed that urea furfural resin with molar ratio of 1 to 2.2 with the highest bond sheer strength is the best resin among others. Nano clay at three levels of 0.5%, 1% and 2 % was added to the best resin of urea furfural and caused improvement in resin properties. So that solid content of resin increased from solid content of control (resin without nano clay ) from 56 % to 56.5 %, 56.65%,and 56.8% respectively for adding 0.5%, 1% and 2% nano clay. Density of resin increased from 1.1 gr/cm3 for control to 1.135, 1.14, and 1.145 gr/cm3 for adding 0.5%, 1% and 2% nano clay. Viscosity from 95 second for control to 135,140,143 seconds respectively for adding 0.5%,1 % and 2%nanoclay. Bond shear strength from 1.7 MPa for control to 2.7,0.6 and 0.8 MPa respectively fot 5%,1% and 2% nano clay. Gel time reduced from 180 seconds for control to 160, 145,140 seconds respectively for 0.5% ,1% and 2% nano clay. Findings of this study showed that free formaldehyde urea furfural resin with urea to furfural molar ratio of 1 to 2.2 has the highest bond sheer strength (1.62 MPa) and adding 0.5 percent Nano clay to this resin caused an improvement in its bond sheer strength, density, solid content, viscosity, and gel time. Improvement by adding nano clay up to 5.0% was noticeable but improvement by adding higher levels of nano clay was low. Regarding above results it can be concluded that produced urea furfural with urea to furfural molar ratio of 1 to 2.2 and adding o.5 % nano clay is a suitable substitution for urea formaldehyde resin which can be recommended for particleboard and medium density fiberboard industries.

Wood plastic composite that briefly (WPC) called are a new class of composite materials that in recent years have been the attention of many researchers and a major part of the industry. For improve some properties of wood plastic composite, various nanoparticles was used that one of them is clay that due to the high specific surface and mineral source, improves properties of nanocomposite. Therefore this study with aim to investigation the effect of nanoclay and polypropylene oxide coupling agent (OPP) on Phragmites australis flour/waste polypropylene was done.
For this purpose first polypropylene was oxidized in molding phase and in the presence of atmospheric oxygen and alcohol. Then Phragmites australis flour and polypropylene with were mixed weight ratio of 50% in internal mixer. Nanoclay to 3 levels 0, 2 and 4% and coupling agent to 2 levels 0 and 3% were used. Test boards were made using a hot press. Physical properties such as long-term water absorption and thickness swelling, humidity coefficient diffusion and thickness swelling rate, thermal properties such as thermal analysis (TGA) and morphological properties such as X-ray diffraction (XRD), the field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) were done. To ensure the oxidation of polypropylene as well as infrared spectroscopy (FTIR) were used.
The results showed that the long-term water absorption and thickness swelling, humidity coefficient diffusion and thickness swelling rate were decreased with increasing of nanoclay and coupling agent (OPP),. Thermal properties of nanocomposite improved with increasing of nanoclay and coupling agent. The result of field emission scanning electron microscopy (SEM) showed that by addition of coupling agent, the interface between two phase's lignocellulosic fiber and polymeric matrix improvement. The result of X-ray diffraction (XRD) showed that with increasing of nanoclay to 2%, the distance between the silicate layers of clay increased but by addition 4T nanoclay, the distance between the silicate layers slightly decreased and type in nanocomposite structure is intercalation. The transmission electron microscopy (TEM) as well as approved this. The result of infrared spectroscopy (FTIR) indicates the oxidation of polypropylene in the presence of oxygen.
As a general conclusion can be said that the use of nanoclay and compatibility oxidized polypropylene (OPP), improved properties of Phragmites australis flour/polypropylene nanocomposite. Therefore, the use of 2% nanoclay (for cost-effectiveness) with 3% OPP for the manufacture of composites with desirable features is recommended. K

In this research, the effect of nanoclay on physiochemical, thermal and structural properties of urea formaldehyde resin (UF) was investigated. The prepared GLUF resin was mixed mechanically with the 0.5, 1 and 1.5% nanoclay for 5 min at room temperature. The physicochemical properties of the prepared resins were measured according to standard methods. Also, the thermal and structural changes in UF resin containing nanoclay were measured by Differential Scanning Calorimetry (DSC), Fourier Transform Infrared Spectrometry (FTIR) and X-ray Diffractometry (XRD). The physicochemical test results indicated that by addition of nanoclay the viscosity, solid content and density values were increased while the free formaldehyde and gelataion time of resin were decreased. FTIR analysis indicated that the addition of nanoclay decreased the methylene linkages in UF resin. Moreover, the new peak was appeared at 850 and 1140 cm-1 bands in nanoclay filled UF resin dealing that a chemical interaction between nanoclay and UF resin was accrued. According to DSC analysis nanoclay accelerates the curing temperature of resin while the onest and temperature peaks dramatically decreased. XRD analysis showed that nanoclay completely exfoliated in UF resin.

This study conducted to evaluate the possibility of making plywood from Ecalyptus Comuldulensis wood using oxidation of layer surfaces and application of nano-clay as adhesive filler. First Ecalyptus wood layers treated with hydrogen Peroxide and sulfuric acid using 50 gr/m2. Nano-clay was added to UF resin at three levels (1. 5، 3 and 4. 5 percent) based on resin solid content. Modified resin with nano-clay were applied on treated layers. Oxidated specimens were evaluated using FTIR spectroscopy. Control specimens were made using untreated Ecalyptus wood layers and UF resin and wheat flour as filler. All boards were made under press pressure of 150 kg/cm2، 160 oC and press time of 4. 5 and 5. 5 minutes. Finally boards strength was evaluated following ISO standard. Results showed that oxidation of layer surfaces and application of nano-clay as filler had negative effects of plywood when UF resin is used. Analysis of results using ANOVA technique showed that differences exist among all tests except effect of oxidation on MOE parallel and perpendicular of Fiber were significant.

The main objective of this work was to study the effects of nanoclay (NC)، microcrystalline cellulose (MCC)، and coupling agent (MAPP) on the mechanical and thermal properties. The results showed that mechanical properties of the composites made with MCC were significantly superior to those of unfilled. Addition of MAPP could enhance the mechanical and thermal properties of the blends، due to the improvement of interface bond between the filler and matrix. The significant improvements in tensile properties of the blends composites made with MAPP and NC were further supported by SEM micrographs. The thermo gravimetric analysis indicated that the addition of 5 wt. % MAPP and 3 wt. % NC remarkably increased the thermal stability of the blends compared to the pure PP. It is to be noted that MCC could not improve the thermal stability.