عنوان مقاله [English]
Background and objectives
One of the important parts in the wood and paper industry are synthetic resins used. Epoxy resins, such as polymers are widely used in various industries and industrial adhesives. That obtained the compound bisphenol A and epichlorohydrin. Bisphenol A of the epoxy resins in the formulation is obtained from the petroleum products, that these products are limited and exhaustible, expensive and cancer. The presence of bisphenol A, in the environment, can be a serious threat to human health and the environment. Research conducted in the field of bio-based epoxy resins such as Shakeri et al (2010) used to soybean epoxy resin in in strawboard. Tasooji et al (2010) compared to the base resin of formaldehyde and epoxy soybean resin were examined in straw boards. The aim of this study was to synthesis of bio based tannin epoxy acrylate and producing particleboard with them and evaluated the mechanical and physical properties.
Materials and methods
In this study, for the production of three layer particle board with bio-based tannin epoxy acrylate resin, fine wood chips to the surface layer remind 20 mesh and coarse wood chips pass to 20 mesh that was used for the middle layer. In order to reduce the moisture in wood with a moisture content of 2.5%, the particles put auto temperature for 8 hours at 103°C, respectively. Commercial tannin extracted from the bark mimosa, which is brown and dry powder contains 82% monomers and oligomers is flavonoid chemistry of Silva France was prepared. For synthesis of bio based tannin epoxy acrylate resin, acrylic acid (99%), hydroquinone (99%) and catalyst 4- Diazabicyclo [2,2,2] octane was used Sigma-Aldrich Co. Glycidyl ether tannin reacted with acrylic acid and hydroquinone and catalyst at a temperature of 95 °C for 12 hours and tannins epoxy acrylate resin was prepared. Using Fourier transform infrared spectroscopy was investigated final structure of the resin. Then in a three-layer board was made with tannin epoxy acrylate resin, at press temperatures of 160 and 180 °C and press time for 5/5 and 7/5 minutes with a nominal density of 700 kg/m3 and mechanical and physical properties were measured such as flexural strength (MOR), modulus elasticity (MOE) and Internal bending (IB) according EN310 and EN319 standards and physical properties such as water absorption (WA) and thickness swelling (TS) (after 2 and 24 hours immersion in water), according to standard EN317.
Acrylic acid reacts with the glycidyl ether tannin, in place of epoxy groups, acrylic groups are causing ripple branches combined. FTIR results confirmed the presence of acrylic resin. The results showed that increasing press temperature and press time had positive effect on physical and mechanical properties have been made. Flexural strength with increasing temperature and time after 13/3 to 16/3 MPa, the modulus of elasticity of 2600 MPa and 3600 Mpa, IB from 0.4 to 0.8 increased. Because a rise in temperature and press time, due to faster evaporation and condensation of moisture and soften the particles in the beam better and better heat transfer to the middle layer and curing the resin in the middle layer board and increase the strength. As temperatures rise and the press time, the thickness swelling has decreased after 2 hours from 11% to 7% and after 24 hours from 17 percent to 12 percent. The water absorption has decreased after 2 hours from 25% to 17% and after 24 hours from 30% to 21% .