乙二醛对蛋白基胶黏剂结构及性能的影响

选用2种典型蛋白原料大豆粉及谷蛋白粉,通过刨花板内结合强度性能测试及CP-MAS 13CNMR分析,对比乙二醛化蛋白基胶黏剂与甲醛化蛋白基胶黏剂的性能特征。结果表明,乙二醛与蛋白分子之间发生了化学反应,但由于其交联程度不及甲醛化蛋白胶黏剂,导致其胶接性能不及后者,若提高pMDI等交联剂的添加量,乙二醛化蛋白胶黏剂也可用于人造板制备。     

Tests for outdoor window profiles: 90° mortise tenon corner joints strength assessment

The research focuses on the assessment of the performances of glued laminated wood corner joints for outdoor window profiles applications, proposing a methodology to appreciate the strength of 90° tenon mortise corner joints. The rationale relies on the potential damage (i.e. breaking of the frame) that can be caused by poor glueing processes and/or typology of adhesives. There is a number of standards for assessment of wood-adhesive bonds for outdoor windows; however, there is a lack of specific standards related to glueing assessment for outdoor wood frames, which can take into account all the factors influencing the glueing quality. The proposed methodology was tested on red oak window profiles. A commercially available polyvinyl acetate-based adhesive was used for corner joints. Bending strength of 90° tenon mortise corner joints was measured and compared with maximum admissible loads on the frame to limit its deformations within admissible ranges. The test results show that the 90° tenon mortise corner joints strength exceeds the admissible load to preserve the functionality of the frame. In order to appreciate the influence of conditioning processes on adhesion, shear strength tests of the flatwise glued joint samples (bond lines of lamellae) were carried out after different conditioning processes.     

聚氨酯在人造板行业的应用

人造板行业的升级转型为聚氨酯等不含甲醛的高分子材料的发展带来了机遇。笔者介绍了几种与人造板行业密切相关的聚氨酯材料的特点以及在人造板中的典型应用,并探讨了目前聚氨酯存在的问题和今后的发展方向。     

动纤组织粘合剂羊 猪皮肤粘合效果的实验研究

用本课题组研制的动物纤维蛋白原复合物新型生物组织粘合剂粘合羊背部皮肤切口和猪左臁部正中切口,并与传统的缝合切口对比实验结果表明,粘合切口比缝合切口操作简便,创缘对合整齐;术后炎症轻、愈合快、感染少;愈合后瘢痕小、平整美观。该粘合剂可以有效地粘合皮肤较厚、张力较大的皮肤切口。实验结果为该粘合剂在兽医和医学临床的应用提供了依据。     

Durability of isocyanate resin adhesives for wood III: degradation under constant dry heating

The durability of isocyanate resins consisting of emulsion-type polymeric diphenylmethane diisocyanate (EMDI) was investigated under constant dry heating. Two kinds of resin, water only-added resin and polyol/wateradded resin, were used in this study. The kinetic studies based on the weight losses of the resins were carried out by isothermal thermogravimetry (TG) at temperatures ranging from 260° to 320°C. The apparent activation energies of the resins were calculated for weight losses of 5%, 10%, and 15%. The values of apparent activation energy of the resins increased with increasing weight loss. The bond-strength reductions of the specimens bonded with the resins were observed at various temperatures from 120° to 180°C. The best-fitting regression function for the behavior of bond-strength reduction was determined statistically. The apparent activation energy of each resin was calculated from the regression function for the half-life period. According to the calculated values, the adhesion durability of polyol/wateradded resin was superior to that of water only-added resin. To speculate on the changes in weight loss and the chemical structure of the resins in the glue lines under dry heating, changes in the cured resins were also observed.Part of this paper was presented at the 49th Annual Meeting of the Japan Wood Research Society, Tokyo, 1999     

Preparation of phenol formaldehyde resin from phenolated wood

The technique for preparing phenol formaldehyde resin from phenolated wood (PWF) and its characters were studied and analyzed. Poplar (Populus spp) wood meal was liquefied by phenol in the presence of sulfuric acid as a catalyst. After the liquefied products were cooled, alkaline catalyst and formaldehyde were added. The mixture was kept at (60±2)°C for 1h and then was heated to (85±2)°C for 1h. The influence of molar ratio of formaldehyde to phenol (F/P) was investigated. The results showed when the molar ratio of formaldehyde to phenol was over 1.8, the PWF adhesives had high bond quality, bond durability and extremely low aldehydes emissions. Foundation item: The research was supported by Sino-Japanese Technical Cooperation Project (2-1-b) and the key technologies R & D Program for the 10th Five-Year Plan (325-11). Biography: LI Gai-yun (1974-), female, Assistant professor in Research Institute of Wood Industry, Chinese Academy of Forestry, Beijing 100091, P. R. China Responsible editor: Zhu Hong     

用MS—03改性三聚氰胺树脂改善模压木制品耐水性的研究

本文阐述了在脲醛树脂中加入MS—03改性三聚氰胺树脂的方法,此法可以降低模压木制品的吸水厚度膨胀,提高产品的耐水性,使所得制品适用于我国南方湿热地区。     

Comparison of protein-based adhesive resins for wood composites

The search for new value-added uses for oilseed and animal proteins led us to develop protein-based wood adhesives. Low-fat soy and peanut flours and blood meal were hydrolyzed in an alkaline state, and PF-cross-linked protein resins were formulated by reacting the protein hydrolyzates with phenol-formaldehyde (PF) in solid-tosolid ratios ranging from 70% to 50% hydrolyzates and 30% to 50% PF. Physical properties of medium density fiberboard (MDF) bonded with protein-based phenolic resins were compared to those of boards bonded with ureaformaldehyde (UF) and PF resins, and flakeboard bonded with soy protein-based phenolic resin was compared to PF-bonded board. As MDF binders, adhesive properties of protein-based phenolic resins depended upon protein content of proteinacious materials. MDF board bonded with blood-based phenolic resin was comparable to PF-bonded board and met the requirements for exterior MDF. Boards bonded with soy-protein-based phenolic resin met requirements for interior MDF, while peanut-based phenolic failed to meet some of the requirements. Flakeboard bonded with soy-protein-based phenolic resins was inferior to PF-bonded board but outperformed PF-bonded board in accelerated aging tests. Although they exhibit a slow curing rate, the cost effectiveness and superior dimensional stability of protein-based phenolic resins may make them attractive for some uses.     

湿固化胶粘接高含水率染色和固色桦木胶接性能探讨

为了系统研究不同表面状态下桦木单板的胶接性能,在比较桦木素材、染色桦木以及固色桦木表面润湿性能的基础上,采用湿固化异氰酸酯胶黏剂,对比分析了素材、染色和固色桦木3种试件在含水率30%、50%、70%和90%条件下的干状及湿状胶接强度.结果表明:随着含水率的升高,素材、染色和固色桦木表面的平衡接触角均呈上升趋势,胶接强度均呈下降趋势,并且其湿状胶接强度均明显低于各自的干状胶接强度;素材的干湿状胶合强度均明显高于染色和固色两种试件.     

Durability of isocyanate resin adhesives for wood I: Thermal properties of isocyanate resin cured with water

The thermal properties of isocyanate (IC) resin cured with water were studied using dynamic mechanical analysis (DMA) and Fourier transform infrared spectroscopy. The thermal properties of cured phenol formaldehyde (PF) resin were also studied for comparison purposes. The DMA specimens were prepared using a unique technique. The relation between the mechanical and chemical changes of the resin during DMA was clarified. The cured PF resin had better thermal stability than the IC resin cured with water. The improvement of thermal stability in cured IC resin by heat treatment was considered to be less effective. The effect of the heating rate on the mechanical properties was also investigated. The apparent activation energy in the thermal degradation of cured IC resin was calculated based on the results obtained.Part of this paper was presented at the 47th Annual Meeting of the Japan Wood Research Society, Kochi, April 1997