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The aim of the study was to investigate the effect of nanocellulose (cellulose nanocrystals [NCC]) addition to urea-formaldehyde (UF) resin on the properties of plywood and the possibility of reducing resin spread rate in plywood production. The studies have shown the increase in viscosity of experimental adhesive mixture in comparison with reference one. On the basis of the bonding quality results, it was concluded that the NCC-reinforcement led to significant improvement in bonding quality of plywood. Moreover, values of bending strength (modulus of rupture) and modulus of elasticity also increased because of the cellulosic nanoparticles introduction. The positive effect of NCC addition on the properties of plywood allowed the reduction of resin spread rate by 50 g/m2 and maintaining equally good strength as reference panels. The modification with nanocellulose itself did not lead to a decrease of free formaldehyde content. However, allowing the reduction of adhesive application led to a slight decrease in the amount of emitted formaldehyde. 相似文献
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Juanito P. Jimenez Jr 《Journal of Adhesion Science and Technology》2013,27(24):2658-2666
The study investigated the use of tobacco (Nicotiana tabacum L) stalk particles as additive with both extender and filler property in urea formaldehyde adhesive formulation used to bond Paraserianthes falcataria (L) Nielsen veneers into plywood. The effect of varying amount of tobacco stalk particles on adhesive working properties, shear strength and wood failure of 3-ply plywood was investigated. Adhesive mix containing urea formaldehyde resin with tobacco stalk particles up to 8% by mass blended very well and remained stable for atleast 1?hour. An increase or no significant effect on shear strength and wood failure up to 8% tobacco stalk loading was observed compared to plywood that used a commercial glue formulation. Based on shear strength and wood failure, panels containing 4–8% tobacco stalk particles would pass the requirements of ISO 12466-2. Examination of adhesive penetration and plywood strength suggest that tobacco particles could function as both filler and extender. Tobacco stalk particles offer an environmentally friendly, low cost, strong and non-abrasive alternative to conventional fibers used in plywood production. 相似文献
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Amorn Petsom Sophon Roengsumran Supattra Hanphichanchai Polkit Sangvanich 《应用聚合物科学杂志》2003,89(7):1918-1924
A brominated phenol–formaldehyde resin was investigated as a plywood adhesive to study the effect of bromine on the physical and flammability properties of this resin. The results of these studies showed that brominated phenol–formaldehyde resin of 10% bromine content by weight of the phenol–formaldehyde resin was suitable to be used as a plywood adhesive. The optimal compressing temperature and compressing time were 110°C and 30 min, respectively. The prepared plywood obtained from the optimal condition gave a high shear strength, good flame retardancy, and good resistance to both hot and cold water. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1918–1924, 2003 相似文献
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Marzieh Gangi Taghi Tabarsa Sima Sepahvand 《Journal of Adhesion Science and Technology》2013,27(13):1407-1417
The aim of this work is to evaluate performances of tannin-based resins designed as adhesive in the plywood production. For this purpose, a part of phenol formaldehyde (PF) and melamine formaldehyde (MF) in the classic adhesive formulation was replaced by tannin. The physical properties of the formulated resins (rheological characterization, etc.) were measured. In order to analyze the mechanical performance of tannin-based resins, plywood panels were produced and the mechanical properties including tensile strength wood failure and three-point bending strength were investigated. The performance of these panels is comparable to those of plywood panels made by commercial PF and MF. The results showed that the plywood panels bonded with tannin–PF (PFT) and tannin–MF (MFT) resins exhibited better mechanical properties in comparison to the plywood panels made of commercials PF and MF. The introduction of small properties of tannin in PF and MF resins contribute to the improvement of the water performance of these adhesives. The formaldehyde emission levels obtained from panels bonded with tannin-based resins were lower than those obtained from panels bonded with control PF and MF. Although there are no actual reaction at all between PF, MF, and tannin, addition of tannin significantly improves the water resistance of PF and MF resins. This is a novel finding that manifests the possibility of replacing a convention PF and MF resins by tannin. Modified adhesive is one of the goals in the plywood production without changing any of their production conditions with improvement to their overall properties. 相似文献
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To lower the formaldehyde emission of wood‐based composite panels bonded with urea–formaldehyde (UF) resin adhesive, this study investigated the influence of acrylamide copolymerization of UF resin adhesives to their chemical structure and performance such as formaldehyde emission, adhesion strength, and mechanical properties of plywood. The acrylamide‐copolymerized UF resin adhesives dramatically reduced the formaldehyde emission of plywood. The 13C‐NMR spectra indicated that the acrylamide has been copolymerized by reacting with either methylene glycol remained or methylol group of UF resin, which subsequently contributed in lowering the formaldehyde emission. In addition, an optimum level for the acrylamide for the copolymerization of UF resin adhesives was determined as 1%, when the formaldehyde emission and adhesion strength of plywood were taken into consideration. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献
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Determination of formaldehyde and TVOC emission behavior from interior use plywood using various post heat treatment processes
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To reduce the formaldehyde/TVOC emissions from plywood with melamine–urea–formaldehyde (MUF) resin, four heat treatment procedures were designed and applied. Five‐ply plywood was fabricated, and its formaldehyde/TVOC emissions and wet shear strength were tested. Results showed that a simple low/no pressure post heat treatment procedure was effective and practical to decrease the formaldehyde/TVOC emissions from plywood. This was attributed to completely cured of MUF resin, the breakage of unstable chemical bonds, the acceleration of free formaldehyde releasing, and the exposed surface of the plywood. Meanwhile, this process also balanced the interior force of the resultant plywood and improved its wet shear strength. Under a 12 h oven heat treatment procedure after hot press, the formaldehyde and TVOC emissions from plywood decreased to 0.020 and 0.036 ppm, respectively, while the surface and core layer wet shear strength of plywood was improved to 1.24 and 1.08 MPa. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44909. 相似文献
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《Journal of Adhesion Science and Technology》2013,27(3-4):211-225
In this study we investigated the effects of using four additives, wheat flour (WF), tannin, rice husk (RH) and charcoal, to melamine-formaldehyde (MF) resin for decorative veneer and base plywood in engineered flooring in order to reduce the formaldehyde emission levels and improve the adhesion properties. We determined the effects of variations in hot-press time, temperature and pressure on the bonding strength and formaldehyde emission. Blends of various MF resin/additive compositions were prepared. To determine and compare the effects of the additives, seven MF resin blends were prepared with the four different additives: four with a wt ratio of 8:2 (MF/WF, MF/tannin, MF/RH and MF/charcoal), and three in the wt ratio of 8:1:1 (MF/WF/tannin, MF/WF/RH and MF/WF/charcoal). The desiccator and perforator methods were used to determine the level of formaldehyde emission. The formaldehyde emission level decreased with all additives, except for RH. At a charcoal addition of only 20%, the formaldehyde emission level was reduced to nearly 0.1 mg/l. Curing of the high WF and tannin content in this adhesive system was well processed, as indicated by the increased lap-shear strength. In the case of WF, the lap shear strength was much lower due to the already high temperature of 130°C. The adhesive layer was broken when exposed to high temperature for extended time. In addition, both WF and tannin showed good mechanical properties. With increasing WF or tannin content, the initial adhesion strength increased. The MF resin samples with 20% added tannin or WF showed both good lap shear and initial adhesion strengths compared to the pure MF resin. 相似文献
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Qiang Gao Sheldon Q. Shi Shifeng Zhang Jianzhang Li Xiaomei Wang Wubin Ding Kaiwen Liang Jinwu Wang 《应用聚合物科学杂志》2012,125(5):3676-3681
Soybean meal flour, polyethylene glycol (PEG), sodium hydroxide (NaOH), and a melamine-urea-formaldehyde (MUF) resin were used to formulate soybean meal/MUF resin adhesive. Effects of the adhesive components on the water resistance and formaldehyde emission were measured on three-ply plywood. The viscosity and solid content of the different adhesive formulations were measured. The functional groups of the cured adhesives were evaluated. The results showed that the wet shear strength of plywood bonded by soybean meal/NaOH adhesive increased by 33% to 0.61 MPa after adding NaOH into the adhesive formulation. Addition of PEG reduced the viscosity of the soybean meal/NaOH/PEG adhesive by 91% to 34,489 cP. By using the MUF resin, the solid content of the soybean meal/MUF resin adhesive was improved to 39.2%, the viscosity of the adhesive was further reduced by 37% to 21,727 cP, and the wet shear strength of plywood bonded by the adhesive was increased to 0.95 MPa, which met the interior plywood requirements (≥0.7 MPa). The formaldehyde emission of plywood bonded by the soybean meal/MUF resin adhesive was obtained at 0.28 mg/L, which met the strictest requirement of the China National Standard (≤0.5 mg/L). FTIR showed using the MUF resin formed more CH2 group in the cured adhesive. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 相似文献
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乳清蛋白是干酪加工过程中所产生的一种副产品,除被用作食品添加剂外,仍有相当数量乳清蛋白并未得到有效利用。为了实现乳清蛋白的高附加值利用,本文以乳清蛋白为原料,研制了具有良好耐久性和环保的乳清蛋白基胶合板用水性胶粘剂,并评价了变性处理、改性剂种类及其用量对乳清胶粘剂的胶合性能及游离甲醛释放量的影响。结果表明,热变性使乳清蛋白胶粘剂的胶接耐久性提高;不同改性剂对乳清蛋白胶粘剂的性能影响不同。采用1%多异氰酸酯改性胶接耐久性最好;采用0.15%戊二醛/1%乙二醛改性胶接强度最高。中试结果表明,所研制的耐水性环保乳清蛋白基胶合板胶粘剂的干胶接强度达到1.98MPa,煮-烘-煮28h后湿胶接强度为1.14MPa,游离甲醛释放量仅为0035mg/L(干燥器法),达到了1ISK6806--2003环保结构胶合板用胶粘剂要求。 相似文献
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Nanoclay is a natural mineral that has great potential as a reinforcing filler in wood adhesives. In order to investigate the reinforcing mechanism more clearly, the crystalline structure, chemical properties, morphology, and thermal stability of pure PF and organic nanoclay-reinforced phenol formaldehyde (PF-OMMT) adhesive were characterized. The comparative mechanical properties of pure PF adhesive and PF-OMMT in the bondlines of plywood were analyzed by nanoindentation (NI) under different service environments and the shear strain distribution on the interphase was also measured by a digital image correction technique (DIC). X-ray diffraction (XRD), Fourier transform infrared (FTIR) and transmission electron microscopy (TEM) results indicated good dispersion of the clay in the PF matrix. The modified adhesive showed greater thermal stability than did the control adhesive, as evaluated by thermo-gravimetric analysis (TGA). The good dispersion of nanoclay and the positive effects of the nanoclay on the adhesive's water and heat resistance may have contributed to the improved mechanical properties of adhesives in an accelerated durability test. Compared to pure PF, the reduced elastic modulus and hardness of PF-OMMT in the bondline increased significantly and the strain distribution was much more uniform, resulting in an observed increase of macro-bonding strength of plywood, especially under conditions of severe cyclic water saturation and drying. 相似文献
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Effects of diatomite inorganic fillers on the properties of a melamine–urea–formaldehyde resin
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In this study, a low‐cost diatomite was used to partly substitute wheat flour as one type of melamine–urea–formaldehyde (MUF) resin filler. Five‐ply plywood was fabricated, and its performance was measured. The crystallinity, fracture surface, and functional groups were tested to determine the effects of diatomite on the performance of the MUF resin. The results show that diatomite was well distributed in the MUF resin system and formed an embedding structure; this improved the wet shear strength of the resulting plywood by 33% to 1.36 MPa. Diatomite captured the free formaldehyde in the resin and the microporous structure formed in the resin accelerate formaldehyde release of the plywood. Consequently, the formaldehyde emission of the plywood was reduced. The diatomite partly replaced wheat flour as an MUF resin filler and could be applied in the plywood industry. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44095. 相似文献
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Hamed Younesi-Kordkheili Antonio Pizzi Ali Mohammadghasemipour 《The Journal of Adhesion》2018,94(5):406-419
The aim of this research was to investigate the effect of polymeric 4, 4 diphenyl methane diisocyanate (pMDI) on the physical and mechanical properties of plywood panels bonded with an ionic liquid (IL)-treated lignin-urea-formaldehyde resin. Soda lignin modified by 1-ethyl-3-methylimidazolium acetate ([Emim][OAc]) IL was added to a urea formaldehyde (UF) resin during resin synthesis to prepare a lignin-urea-formaldehyde (LUF) resin. pMDI at various contents (2, 4, and 6% on resin solids) was then added to prepare a LUF resin. The thermal and physicochemical properties of the resins prepared as well as the water absorption, shear strength, and formaldehyde emission of the plywood panels bonded with them were measured according to standard methods. DSC analysis indicated that the addition of pMDI decreases the gel onset and curing temperatures of the LUF resin. According to the results obtained, the addition of pMDI significantly increased the viscosity and solid content and accelerated the gelation time of LUF resins. Based on the findings of this research, the addition of pMDI dramatically improves the performance of LUF resins as a new adhesive for wood-based panels. The LUF resins with isocyanate added yielded panels presenting lower formaldehyde emission and lower water absorption content when compared to those bonded with the control LUF resins. Greater dry and wet shear strength can be obtained by a small addition of pMDI to LUF resins. 相似文献
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