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181.
以多亚甲基多苯基多异氰酸酯(PAPI)和聚醚多元醇为原料合成了一种单组分、室温湿固化的端异氰酸酯聚氨酯胶粘剂。本研究考察了物料的化学组成对胶粘剂粘接木材的力学性能产生的影响。实验表明,与改性二苯基二异氰酸酯(MD I)相比,PAPI合成的胶粘剂对木材粘接干压剪强度提高了60%;将相对分子质量(MW)为800、1 000和2 000的聚氧化乙烯二醇(PED)、MW为300和3 000的聚氧化丙烯三醇(N303和N330)以及聚四氢呋喃-氧化丙烯二醇(NG220)按优化的比例复合使用,以改性胺和有机锡复合催化,可有效提高粘接木材的干和湿压剪强度、固化速率以及木破率。FT-IR光谱证实聚醚多元醇的—OH与PAPI的—NCO反应生成了氨基甲酸酯(—NHCOO—),但N—H和C O均以氢键形式存在。 相似文献
182.
Yasumitsu Uraki Junji Nemoto Kuniyoshi Yanaga Akio Koizumi Takuro Hirai 《Journal of Wood Science》2005,51(6):589-594
Board-shaped composites with medium density (MDF) were prepared from isolated lignins and waste newspaper, in addition to
preparation of the composites with high density (HB). The board properties of both composites concerning bending strength
and water resistance were improved by the addition of hardwood acetic acid lignin (HAL). The internal bond strength and water
resistance of MDF, in particular the degree of thickness swelling (TS), were also improved by prolonged molding time. Adding
inorganic salts contributed to the improvement of TS. The effect depended on the charge of the cation. Considering practical
utilization of lignin-based MDF as a structural material, its performance was evaluated by combination of the single-shear
test of nailed joints and the modulus of rigidity. As a result, this MDF had sufficient strength to be utilized as an internal
shear wall material. Therefore, lignin can be considered as an alternative to conventional adhesives for the production of
boards such as HB and MDF. 相似文献
183.
聚氨酯预聚体的合成及其在木材粘接领域的应用 总被引:9,自引:0,他引:9
本文研究了聚氨酯预聚体的合成工艺,测试了固化后的聚氨酯胶粘剂胶片的性能,讨论了分子结构对拉伸强度和伸长率的影响,同时进行了聚氨酯粘剂用于含水率木材粘接的试验,结果表明,具有线型结构的,高分子量的胶粘剂延伸性好,但拉伸强度稍低,聚氨酯胶粘剂可以用于高含水率木材的粘接。 相似文献
184.
This study investigated the liquefaction of bamboo in phenol, which involved the effects of weight ratios of phenol to bamboo,
amount of catalyst, temperature, etc. The study showed that liquefaction could be accomplished with a phenol to bamboo weight
ratio of 2–1: 1, a 5% catalyst of HCl or BF3, and a temperature of 115°C. Liquefied bamboo formaldehyde (BLF) resin adhesive for exterior use could be obtained with a
phenol to formaldehyde molar ratio of 1:1.6–2.0. The curing behavior of BLF resin adhesive, studied by TG-DSC and IR analyses,
showed that BLF resin adhesives had a lower curing temperature than PF adhesives but had the same characteristic trough in
IR spectra as PF adhesives.
__________
Translated from Chemistry and Industry of Forest Products, 2004, 24(3) [译自: 林产化学与工业, 2004, 24(3)] 相似文献
185.
三聚氰胺改性脲醛树脂胶粘剂在中密度纤维板上的应用研究 总被引:13,自引:1,他引:13
耐水性差、游离甲醛释放量高是我国中密度纤维板(MDF)存在的两个主要问题。用三聚氰胺改性脲醛树脂(MUF)胶粘剂生产MDF可以有效地提高耐水性,降低游离甲醛释放量,并使得因管道施胶引起预固化问题得到有效控制。 相似文献
186.
187.
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. 相似文献
188.
无机硅化物接枝脲醛树脂木材胶粘剂 总被引:5,自引:2,他引:5
介绍了一种新型无机硅化物接枝脲醛树脂胶粘剂制备方法及性能,并与普通脲醛树脂进行了对比实验。该接枝脲醛树脂游离甲醛含量较低,胶合强度优良,耐水性、耐热性、耐燃性良好,适用于人造板的制造。 相似文献
189.
190.