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《木材工业》2021,(3)
采用低分子量聚乙二醇200(PEG-200)与实验室合成的水性超支化聚丙烯酸酯(HBPA)分散有机蒙脱土(OMMT)乳液作为木材浸渍处理改性剂,对青杨(Populus cathayana Rehd.)边材进行浸渍处理,并对改性剂及其改性处理材进行化学结构分析以及形貌表征,分析改性剂对处理材的作用机理以及改性剂在处理材内的形态,并测试处理材的物理力学性能指标。结果表明:PEG-200与HBPA具有较好的相容性,OMMT在其中呈部分剥离状态;经过浸渍处理,部分HBPA和OMMT能够进入到木材细胞壁内,PEG能在HBPA和木材之间形成交联作用,但OMMT质量分数在4%时,部分OMMT填充在木材细胞腔内。改性剂处理材的物理力学性能提升,但OMMT质量分数4%相对2%的提升幅度不大。 相似文献
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采用两种粒径(30 nm和150 nm)的SiO2溶胶真空浸渍不同含水率(绝干、气干、调湿)的欧洲赤松和南方松边材,比较其24 h内吸液率变化规律和24 h增重率,并通过质量法分析硅溶胶处理材轴向SiO2的浓度梯度,从而考察处理材的初始含水率对SiO2溶胶在木材中渗透性的影响。研究结果表明:(1)两种木材均在绝干状态下吸液率最低,30 nm硅溶胶在气干状态下吸液率最高,而150 nm硅溶胶在调湿状态下吸液率最高。(2)初始含水率对增重率的影响与吸液率不同,30 nm硅溶胶在调湿状态下浸渍木材的增重率低于绝干状态,欧洲赤松气干状态的增重率最高。(3)初始含水率对试材中整体SiO2量的影响与增重率结果基本一致,欧洲赤松中SiO2轴向分布梯度远高于南方松,其渗透的均匀性较差。 相似文献
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蒙脱土稳定石蜡基Pickering乳液处理材的性能研究 总被引:1,自引:0,他引:1
《林业工程学报》2017,(5)
为了提高木材的防水性和尺寸稳定性,以过氧化二异丙苯(DCP)为自由基引发剂,通过硅烷偶联剂的作用,制备出蒙脱土稳定石蜡基Pickering乳液;采用真空-加压方式浸渍处理青杨(Populus cathayana)边材,考察了DCP质量分数对乳液粒径分布和静置稳定性的影响,分析了处理材增重率、表面硬度、表面润湿性、吸水性和尺寸稳定性的变化,并采用扫描电子显微镜(SEM)对处理材的微观结构进行了分析与表征。结果表明:1)制备出的乳液平均粒径达到微米级(≤2μm),DCP为0.05%质量分数时乳液平均粒径最小,随着DCP质量分数进一步增加,乳液粒径有所增大;2)乳液浸渍处理后,处理材的表面硬度、表面润湿性和防水性均有所提高,其中DCP为0.05%质量分数时的改性效果较好;3)连续、均一的蜡状物附着在木材细胞壁纹孔表面,从而使木材具有较高的疏水性。 相似文献
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使用南方松作为研究材料,使用有机蒙脱土/石蜡复合乳液对试材进行浸渍,结合高温热处理技术对改性材进行X射线衍射(XRD)研究。结果表明,将有机蒙脱土和石蜡等存在结晶结构的物质引入木材中会使木材的相对结晶度提高。将处理材和未处理材的平衡含水率和吸水性进行对比,结果表明有机蒙脱土/石蜡复合乳液浸渍处理可以有效地降低高温热处理材的平衡含水率、吸水率和体积膨胀率,先高温热处理后再使用有机蒙脱土/石蜡复合乳液进行的浸渍处理工艺效果最佳。 相似文献
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In this research, composites based on polypropylene (PP), beech wood flour, and organomodified montmorillonite (OMMT) were
prepared and characterized for their properties. The blend nanocomposites were prepared by melt mixing of PP/WF at 50% weight
ratios with various amounts of OMMT (0, 3, and 6 per hundred compounds (phc)) in a Hakee internal mixer. Then the samples
were made by injection molding. The influence of organomodified montmorillonite contents on clay dispersion, physical and
mechanical properties of PP/wood flour composites were investigated. Results indicated that the flexural strength and modulus,
tensile strength and modulus increased by addition of 3 per hundred compounds (phc) of organomodified montmorillonite (OMMT),
but decreased with 6 phc OMMT addition. However, impact strength, water absorption and thickness swelling of the composites
decreased with increasing nanoclay loading. X-ray diffraction patterns (XRD) and transmission electron microscopy (TEM) revealed
that the nanocomposites formed were intercalated. Also, morphological findings showed that samples containing 3 phc of OMMT
had higher order of intercalation. 相似文献
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With montmorillonite (MMT) organically modified as organophilic MMT (OMMT) and water-soluble phenol formaldehyde resin (PF) as intermediate, Chinese fir (Cunninghamia lanceolata) wood/MMT nanocomposites (WMNC) were prepared via nano intercalation compounding and characterized by XRD, SEM and FTIR. Results show that: 1) the preparation of OMMT is very successful; 2) the self-made PF can effectively intercalate into MMT to increase markably its gallery distance and even exfoliate its nano silicate laminae; 3) the XRD analysis indicates that some exfoliated MMT enters the non-crystallized region of microfibrils in wood cell walls and the crystallinity degree of wood in WMNC decreases; 4) the SEM graphs show that multiform MMT exists in WMNC. Some grains block in wood cell lumen, some layers adhere to the wood surface of the inner cell wall and some exfoliated nanolaminae even insert into wood cell walls; and 5) the FTIR analysis suggests that MMT and wood in WMNC perhaps interact via certain chemical bonding. 相似文献
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Improvement in seed and seedling quality of Acacia auriculiformis after culling phenotypically inferior trees was studied
in a 6-year old seed production area (SPA). A 5-ha plantation was identified, of which 2.3 ha was converted into SPA. The
initial stocking, 1 612 trees·ha−1, was thinned down to 982 trees·ha−1 based on growth characteristics. The following fruiting season, seeds were collected from 10 randomly selected trees in culled
and non-culled stands, and seed physical characters, germination and seedling traits were assessed. Seed weight, seed thickness
and percentage germination increased by 32.1%, 4.43% and 22.37%, respectively in the culled stand compared to the non-culled
stand. Culling also increased the speed of germination, seedling dry weight and seedling vigor index. Heritability values
were high for seed weight (0.974) and seed thickness (0.948) while medium values were observed for percentage germination
(0.577) and total dry weight (0.534). Predicted genetic gain was 11.13% and 11.22% for seed weight and percentage germination,
respectively. The actual gain was 32.1, 51.9 and 22.9% for seed weight, percentage germination and total dry matter, respectively.
In conclusion, SPAs established by culling inferior trees could serve as sources of good quality seeds for reforestation programs
until genetically improved seeds are made available. 相似文献
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LV Wenhua ZHAO Guangjie. Research Institute of Wood Industry Chinese Academy of Forestry Beijing P. R. China . College of Material Science Technology Beijing Forestry University Beijing P. R. China 《中国林业科技(英文版)》2006,5(1):33-39
INTRODUCTIONWood possesses many special properties, such asbeautiful grain, natural color, high strength-to-weightratio, good electricity and heat insulation; and it can beeasily processed, glued or dyed. It is biodegradable,recyclable and environmental-friendly (Wang Tianminet al. 2002). But as a biomaterial, it also has intrinsicdefects as easy decaying, burning and deforming,which largely limits its usage. Nano science andtechnology opens a completely new way to developwood composites… 相似文献
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The nano intercalation compounding of wood and MMT has important implications for the modification of wood and for the development of new materials. With water-soluble phenol formaldehyde resin as an intermediary, the nanocomposites of Chinese fir (Cunninghamia lanceolata) wood and montmorillonite (MMT) were prepared via three impregnation methods, i.e. normal pres-sure, once and twice vacuum methods. Based on the weight percent gain (WPG) of impregnated wood, the effects of compounding wood and MMT in term... 相似文献
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以松木为原料,经炭化制得松木炭,以有机锆聚合物(PZC)为先驱体浸渍松木炭后进一步高温热处理制备得到ZrC木质陶瓷。采用XRD、SEM、FT-IR、TG-DSC分别对样品的物相变化、组成和微观结构进行了表征,研究了热处理温度和杂化材料质量增加率对木质陶瓷显气孔率与力学性能的影响。结果表明:有机锆先驱体裂解过程中生成ZrO_2,进一步可以在1 400℃通过碳热还原反应转化为ZrC相。ZrC木质陶瓷由立方相ZrC和无定形碳组成,生成的木质陶瓷较好地保留了松木模板的管状孔洞结构,部分ZrC相沉积在孔洞内部。木质陶瓷材料显气孔率随着热处理温度的升高而升高,随质量增加率的增加而降低;力学性能随热处理温度和质量增加率的增加而提高,质量增加率为278%的杂化材料在热处理温度为1 400℃时制备的ZrC木质陶瓷具有良好的力学性能,弯曲强度和断裂韧性分别为158 MPa和1.8 MPa·m~(1/2)。 相似文献
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Nitrogen fertilization and aspects of fruit yield in a Missouri black walnut alley cropping practice
Increasing nut production through cultural practices is important to landowners for maximizing economic gain from agroforestry
plantings. This project studied the effects of applying low rates of nitrogen (N) fertilizer during either the spring or late
summer, on pistillate flowers formed, fruits retained, and fruit quality (percentage kernel) in black walnut (Juglans nigra
L.) grown under alley cropping management. Treatments consisted of two forms of nitrogen fertilizers (NH4NO3 and NaNO3) applied in mid-April, or mid-August of 1995 and 1996, and a nonfertilized control group. Pistillate flowers counted in May,
1996, showed that fertilized trees, regardless of timing or form of N applied, produced from 2.3 to 3.4 times the number of
pistillate flowers as unfertilized control trees. Through the season, the fertilized trees had greater fruit retention, and
ended with 2.9 to 4.8 times more walnuts (on a whole tree basis) than nonfertilized control trees. In addition, all fertilizer
treatments resulted in increased nut yields from 1995 to 1996, while unfertilized control tree yields decreased approximately
70%. Summer application of fertilizer showed the greatest benefit to kernel weight. Average kernel weights of nuts from the
summer-fertilized trees increased from 1995 to 1996, while kernel weight averages from spring-fertilized and nonfertilized
trees remained unchanged or decreased.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
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Influence of nitrogen,photoperiod, cutting type,and clone on root and shoot development of rooted stem cuttings of sweetgum 总被引:1,自引:1,他引:0
Rieckermann Heidi Goldfarb Barry Cunningham Michael W. Kellison Robert C. 《New Forests》1999,18(3):231-244
This study was designed to test the effects of nitrogen fertilization, photoperiod, cutting type, and clone on root and shoot development of stem cuttings of sweetgum (Liquidambar styraciflua). Differences in the growth of roots and shoots were observed as a result of weekly applications of varying levels of nitrogen (N) fertilization (0, 25, 50, 100, or 200 mg N/liter). As the concentration of N increased, new-shoot dry weight increased, but root dry weight decreased at rates greater than 50 mg N/liter. The percentage of rooted cuttings surviving also decreased as N concentrations increased past 50 mg N/liter. A night-interruption light treatment did not significantly affect survival percentages or the amount of root and shoot growth. Across all treatments, only 46% of all cuttings produced new-shoot growth within a 15-week period following rooting. Cutting type (terminal or sub-terminal) affected rooted cutting development. A higher percentage of terminal cuttings survived and were deemed plantable. In contrast, sub-terminal cuttings produced more shoot and root growth. Differences among clones were observed for all traits measured.Manipulating N fertilization, in conjunction with using clones that propagate well, has the potential of producing rooted cuttings of a size adequate for plantation establishment. However, higher percentages of cuttings that produce new shoot growth shortly after rooting must be achieved. 相似文献