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通过引入疏水性单体、反应性有机硅单体、交联单体参与乙酸乙烯酯共聚反应,以提高聚乙酸乙烯酯乳液(PVAc乳液)的耐水性能.采用正交试验,确定了乳液合成中各种单体的最佳配比.试验结果表明,通过单体共聚改性,可提高PVAc乳液的耐水性能. 相似文献
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对采用聚乙酸乙烯酯乳液与偶联剂改性酚醛树脂制备铝木复合材料性能的影响进行研究.结果表明:改性酚醛树脂肢粘剂制备复合材料表面胶合强度大于酚醛树脂胶粘剂,胶合强度都超过1.0 MPa,以杨木单板为基材不同混合比例之间表面胶合强度差异性极显著,但以中密度纤维板为基材不同混合比例之间表面胶合强度差异性不显著,随着聚乙酸乙烯酯乳液比例的增加,浸渍剥离性能降低,聚乙酸乙烯酯乳液与酚醛树脂最佳混合比为1:2;偶联剂的添加提高了复合材料的表面胶合强度,两者差异极显著,但偶联剂的加入对静曲强度和弹性模量影响较小,影响不显著. 相似文献
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先以大豆蛋白、乙酸乙烯酯、尿素、过硫酸铵等为主要原料合成大豆蛋白接枝共聚乳液,以剪切强度为衡量指标,最佳反应条件为:尿素浓度3 mol·L-1;单体比例乙酸乙烯酯∶大豆蛋白=1∶2,反应温度68℃;再使用异氰酸酯对其改性,合成异氰酸酯改性大豆蛋白胶,用该胶压制杨木胶合板,经检验干态和湿态剪切强度分别为7.46 MPa和6.01 MPa,达到了II类胶合板要求;进一步将填料、橡胶乳液、交联剂对胶合板性能的影响作出分析得出,填料最优加入比例为10%,橡胶乳液为30%,交联剂在13%以下时,随着用量增加胶合强度增加,适用期减小,超过15%胶合强度下降。 相似文献
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采用连续乳液聚合的工艺方法合成了聚乙酸乙烯酯乳液.考察聚乙烯醇的种类和加入量,MAA、BA的添加量对乳液性能的影响.研究发现,选用217型PVA,添加量为6％,MAA添加量为2％,BA添加量为5％,VAE乳液添加20％时,乳液细腻均匀,聚合稳定性较好,黏度达到24 100mPa.s,干状压剪强度达到8.03MPa,湿状压剪强度达到2.87MPa,冻融稳定性提至4次. 相似文献
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木地板工业中胶粘剂的应用及发展 总被引：1，自引：0，他引：1
本文讨论了木地板工业常用的几种胶粘剂，介绍了脲醛（ＵＦ）树脂、聚异氰酸酯树脂（ＥＰＩ）和聚乙酸乙烯酯（ＰＶＡｃ）以及各类木地板的生产、装配及质量评估。 相似文献
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用经过处理的玉米淀粉对聚醋酸乙稀醋乳液进行改性, 可有效提高其凝胶速度,使初始胶合强度有较大提高。用改性后的聚醋酸乙稀酯乳胶代替指接胶生产集成材, 可满足机械化生产的需要, 并可大大降低生产成本。 相似文献
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High formaldehyde emission and poor water resistance are two main disadvantages of urea formaldehyde (UF) resin. For that reason, a novel polyvinyl acetate (PVAc) type emulsion curing agent was developed in this paper. PVAc type emulsions, including PVAc, the co-polymer of PVAc and N-hydroxymethyl acrylamide (PVAc–NMA), and the ternary co-polymer of PVAc, NMA, and urea (PVAc–NMA–urea), were the main components. Water, aluminum chloride, ammonium dihydrogen phosphate, polypropylene glycol, silicone oil, and urea were the other components. Under heating, aluminum chloride and ammonium dihydrogen phosphate often underwent thermal decomposition and hydrolysis in solution, produce free acid to cure UF resin, so the curing agent could enhance the curing rate, and then shorten the curing time. In this curing agent, ammonium dihydrogen phosphate and urea worked as formaldehyde removers and reacted with free formaldehyde in UF resin, thus the formaldehyde emission exuded from the plywood could be effectively limited and reduced. The bonding strength of plywood was not improved very much, especially the dry bonding strength, but the wet bonding strength was little enhanced for the active hydroxymethyl group contained in PVAc–NMA and PVAc–NMA–urea underwent a self-cross-linking reaction to improve the bonding strength and adhesion force to the bonded substrate. More importantly, the results from the industrial production experiments were shown to be very good. 相似文献
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Alireza Bastani Stergios Adamopoulos Holger Militz 《Wood material science & engineering》2017,12(4):236-241
The shear strength of furfurylated, N-methylol melamine (NMM) and thermally modified wood bonded with emulsion polymer isocyanate, polyvinyl acetate (PVAc), and polyurethane (PU) adhesives was examined. Furfurylation and NMM modification of Scots pine had a significant negative effect on the bonding strength with all adhesives irrespective of the treatment intensity. The obtained low-shear strength values were related to the brittle nature of the wood after modifications rather to the failure of the bondline. PVAc showed a better bonding performance with both furfurylated and NMM modified wood while the combination of furfurylated wood and PU gave the highest reduction in bonding strength (47–51%). Shear strength also decreased significantly after thermal modification in both Scots pine (36–56%) and beech (34–48%) with all adhesives. With the exception of thermally modified beech samples bonded with PU, bondline was found to be the weakest link in thermally modified wood as it was revealed by the wood failure surfaces. Bondline thickness and effective penetration of adhesives did not relate to the shear strength of all modified wood materials. The lower shear strength of modified wood could be attributed to other factors, such as the reduced chemical bonding or mechanical interlocking of adhesives, and the reduced strength of brittle modified wood substrate. 相似文献
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普通乳白胶在使用过程中存在着一定的不足,运用互穿网络型核壳技术进行改性能达到比较好的效果。本研究表明:采用IPN型核壳乳液聚合工艺生产的乳白胶的综合性能优于普通乳白胶,尤其是在贮存稳定性、耐水性、生产成本等方面能得到很大的提升。 相似文献
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《Wood material science & engineering》2013,8(3):128-131
Abstract This study was carried out to determine the effect of knife wear, as measured in hours of use, on the finger-joint strength of silver fir wood (Abies alba), bonded with polyurethane (PU) and polyvinyl acetate (PVAc) adhesives. Wood samples were collected after 1, 32 and 64 h of knife wear. Results showed that as knife wear increased, bending strength or modulus of rupture (MOR) of the finger-jointed samples was reduced by 11.1% (PVAc) to 21.2% (PU) after 32 h of knife wear, and by 19.6% (PVAc) to 27.6% (PU) after 64 h of knife wear, whereas modulus of elasticity (MOE) of the finger-jointed samples was reduced by 10.5% (PVAc) to 12.5% (PU) after 32 h of knife wear, and by 11.7% (PVAc) to 10.0% (PU) after 64 h of knife wear. Tension strength of the finger-jointed samples was reduced by 2.1% (PVAc) to 1.5% (PU) after 32 h of knife wear, and by 5.4% (PVAc) to 16.0% (PU) after 64 h of knife wear. 相似文献
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Chih-Shen Chuang Kuang-Chung Tsai Yi-Chung Wang Ming-Kuang Wang Chun-Han Ko 《Journal of Wood Science》2010,56(3):208-215
Emulsion resins are widely used in wood-based materials for indoor furnishings. Previous studies have demonstrated that the
ability of a material to retard flame arises from the interactions between four major components: i.e., binder resin (BR);
carbonizing substrate (CS); foam-producing substance (FPS); and dehydrating agent (DA). Fire performance as influenced by
wetting and drying cycle (WDC) treatment has not yet been reported. This study aimed to compare the fire performance of materials
coated with EVAc (ethylene vinyl acetate copolymer) and PVAc (polyvinyl acetate copolymer) emulsion resins of differing BR/CS
ratios, subjected to investigation by cone calorimeter. Intumescent formulation significantly enhanced the fire retardancy
of painted plywood by exhibiting lower peak heat release rates (PHRR) and longer time to reach peak release rates. Additionally,
lower BR content in the fire retardant systems further enhanced flame retardancy. The fire retardancy decreases with increasing
the WDC treatment, caused by the weight loss of the coating materials. Infrared (FT-IR) analysis demonstrated that lower BR
content extends the survival duration of the phosphorcarbonaceous structure of chars. The findings in this study enhance the
state-of-the-art understanding of the effect of the intumescent. 相似文献
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Georg Avramidis Gunthard Scholz Evelyn Nothnick Holger Militz Wolfgang Viöl Arndt Wolkenhauer 《Wood Science and Technology》2011,45(2):359-368
In this study, the impact of a plasma treatment using dielectric barrier discharge at atmospheric pressure on wax-treated
beech was investigated by surface energy determination and adhesion tests. Measurements of the surface energy revealed a strong
increase in surface polarity along with increased surface energy as a result of the plasma treatment, pointing to increased
adhesion properties. To evaluate the adhesion properties of a polyvinyl acetate (PVAc) adhesive on beech treated with montan
ester wax and synthetic Fischer–Tropsch wax, a special peel test was applied. This peel test provided evidence of increased
adhesion of the PVAc after plasma treatment of both materials investigated. 相似文献
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This study was conducted to analyze the effect of joint type, and numbers and types of dovetail keys on diagonal tension and compression performance of corner joints in a furniture frame. Joint members were cut from white fir lumber. Butted and mitered joints were constructed with one and two dovetail key(s) with butterfly and H shapes. Joints were glued by polyvinyl acetate (PVAc) and cynoacrylate (CA). Compression capacity of joints was higher than diagonal tension. Mitered joints were stronger than butted ones. Butterfly dovetail keys were superior to H shape keys. Double keys performed better than single key. Experimental joints glued with PVAc were stronger than those glued with CA glue and control specimens. In terms of strength, butterfly dovetailed joints were comparable with doweled joints. 相似文献
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Eka Mulya Alamsyah Liu Chang Nan Masaaki Yamada Kinji Taki Hiroaki Yoshida 《Journal of Wood Science》2007,53(1):40-46
To estimate the potential bonding performance of bonded wood products from tropical fast-growing tree species, a study on
the bondability of Paraserianthes falcataria L. Nielsen, Pinus merkusii Jungh et. De. Vriese, and Acacia mangium Willd from Indonesia was conducted. Two-ply laminations were produced using polyvinyl acetate emulsion (PVAc), urea formaldehyde
(UF), resorcinol formaldehyde (RF), and water-based polymer isocyanate (API) adhesives. In order to determine the bonding
performance, the block-shear test was applied according to the Japanese Agricultural Standard for structural glued laminated
timber under normal conditions and after accelerated-aging treatments. To support this study, the wettability of each wood
species was also investigated through contact-angle measurement. The results showed that the bonding performance of low-density
P. falcataria was better than that of medium-density P. merkusii and medium-density A. mangium, while the bonding performance of medium-density P. merkusii was better than that of medium-density A. mangium. Furthermore, compared with A. mangium, the small contact angle and good wettability in P. falcataria and P. merkusii result in better adhesion and more intimate contact between the wood surfaces and adhesive. 相似文献