共查询到19条相似文献，搜索用时 187 毫秒
1.
在不同的蒸煮压力下,将不同比例的麦秸和木材混合原料分离成纤维,测量筛分值并制作了草木复合中密度纤维板,对比分析了不同蒸煮压力条件对草木复合纤维筛分值,草木复合中密度纤维板的内结合强度、弯曲性能和握钉力的影响。结果表明:蒸煮压力对木纤维的质量影响较大,蒸煮压力为0.8MPa适合草纤维的分离,但破坏了木纤维的热磨,易导致细小木纤维的产生,板材的IB性能高,表面和边部握钉力的差值较小,但是弯曲性能较差;草木比为50∶50时板材的物理力学性能较高。综合上述试验结果,选择蒸煮压力为0.8MPa,草木质量比为50∶50时,制备出的草木复合板材的性能较高。 相似文献
2.
纤维分离是中/高密度纤维板(MDF/HDF)生产线中的一个重要环节。纤维分离的质量关系到MDF/HDF成品的强度和性能。本文对木片、蒸汽、热磨设备密封介质等环节中的水分对生产的影响进行了分析,结合实际,提出如何合理选择和控制水分,提高纤维分离的质量。 相似文献
3.
研究了麦秆在不同预热处理条件下，其纤维化学性质以及制得的中密度纤维板的性能，同时结合施胶量对不同预热处理麦秆纤维板性能的影响，探讨了在麦秆纤维/脲醛树脂胶中密度纤维板生产中施胶量对板性能影响的重要性。结果表明，采用预热温度为160℃左右、预热时间5～7min的处理条件获得的麦秆纤维在16%左右的施胶量时，可获得满足GB/T 11718-1999标准的麦秆纤维/脲醛树脂胶中密度纤维板。 相似文献
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5.
将新型三聚氰胺-尿素-甲醛（MUF）共缩聚树脂应用于中密度纤维板的制备,考察不同热压温度、热压时间对中密度纤维板物理力学性能的影响。结果表明：在压力为4MPa、热压温度为110℃、热压时间为8min时,中密度纤维板的综合性能最优。 相似文献
6.
采用正交试验设计方法,用不同工艺参数压制白千层-尾巨桉中密度纤维板(MDF),并对其力学性能进行测试。结果显示:木片的蒸煮压力对白千层-尾巨桉MDF静曲强度和吸水厚度膨胀率影响较大,而白千层木片与尾巨桉木片的混合比例则对内结合强度影响较大;对4.4 mm厚MDF试验成品的各项性能进行极差分析,得出在白千层与尾巨桉混合比例为1∶1、蒸煮时间为13 min、蒸煮压力0.95 MPa的条件下MDF的质量为最好,符合GB/T 11718-2009中对普通型中密度纤维板的性能要求。 相似文献
7.
一种表面浸润木质纤维板生产技术采用纤维板干法和湿法两种生产工艺的优点进行重组设计,其生产工艺为木材削片→筛选→蒸煮→热磨→分离→干燥→铺装→浸润→预压→齐边→检验→成品。蒸煮采用蒸汽压力为0.55～0.68MPa,时间为3～5min;干燥采用气流温度为180～280℃,时间为10s;热压成型温度为190～230℃,压力3.5～6.8MPa,时间为30～50s/mm。采用表面浸润木质纤维板生产技术生产的防水、阻燃型和一般的硬质纤维板,其强度及材质均匀度都好,产品的质量达到GB12626.1～26.9—90《硬质纤维板》的标准,并且生产过程中能耗低,无废水排放。 相似文献
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9.
《林业实用技术》1977,(8)
干法生产纤维板比湿法生产效率高,产品强度大,机械性能好。但容重降低到0.8克/厘米~3以下时,往往要发生内剥离和尺寸不稳定。为了能生产容重小、质量好的中密度纤维板,采用了适当施加胶料的生产工艺,现简介如下: 本中密度纤维板的干法生产所用原料主要为胶合板厂的废单板、木芯等。先削制成木片,然后用连续蒸煮器蒸煮,通过热磨机 (压力8-12公斤/厘米~2) 分离成纤维,再用压力送入管道。纤维在输送中施加15-25％热固性树脂胶合剂(液体,20％稀释)。施加胶料的纤维用气流送往干燥机进行“急骤干燥”,含水率达4％左右时,即送往拌胶装置施胶。胶料为苯酚树脂和甲酚树脂,施胶量10-20％,再 相似文献
10.
竹木混合纤维的制备直接关系到竹木复合中密度纤维板生产工艺路线的选择。此项研究在比较分析竹、木纤维形态差异的基础上,考察了笮木片混合磨浆的可行性和影响纤维质量的主要工艺参数。结果表明,在适宜的工艺条件下,可以采用竹木片混合磨浆工艺制备用于中密度纤维板生产的竹木混合纤维,在实验室条件下：竹木片混合比和磨浆时间和对纤维质量影响显著。 相似文献
11.
Development of high-performance UF-bonded reed and wheat straw medium-density fiberboard 总被引：10，自引：1，他引：10
Guangping Han Shuichi Kawai Kenji Umemura Min Zhang Takahisa Honda 《Journal of Wood Science》2001,47(5):350-355
Urea formaldehyde resin-bonded reed and wheat straw fiberboards were produced from the fibers made under different steam cooking conditions in refining processes at densities of 500 and 700kg/m3. The effect of steam cooking conditions on the board properties was examined. The steam pressure and cooking time for reed and wheat straws were 0.4MPa/10min and 0.4MPa/5min, respectively, and 0.6MPa/3min and 0.6MPa/10min for both straws. The effect of steam cooking treatment before the fiber refining process on the wettability and weight losses of the straws was also investigated. The results indicated that the mechanical properties and linear expansion of the straw medium-density fiberboard (MDF) were improved with increasing steam cooking pressure and time during the refining process, whereas the thickness swelling (TS) did not vary much. The wettability of the straws was improved by cooking treatment. The steam cooking conditions had little effect on the wettability of the straw surfaces. For reed and wheat straws, the weight losses increased with increasing steam pressure and cooking time. In addition, it was found that the properties of MDF were significantly higher than those of particleboard, especially the internal bond (IB), where the IB values of MDF were more than 10 times higher than those of particleboard. All the properties of the straw MDF, except the TS of wheat board, can meet the requirement of JIS fiberboard standard. The high performances of MDF could be due to the improved wettability and the removal of extractives during the refining process. 相似文献
12.
The effects of thermo-mechanical refining conditions on the properties of medium density fiberboard (MDF) made from black
spruce (Picea mariana) bark were evaluated. The bark chips were refined in the MDF pilot plant of Forintek Canada Corporation under nine different
refining conditions in which preheating retention time was adjusted from 3 to 5 to 7 min and steam pressure was set at either
0.6, 0.9 or 1.2 MPa. The resulting bark fibers were blended with 12% UF resin (based on oven-dry fiber weight) using a mechanical
blender. The resinated fibers were manually formed into fiber mats and hot-pressed into MDF panels using consistent parameters.
Two panels for each refining condition were produced, resulting in a total of 18 panels. Analysis of variance (ANOVA) was
used to analyze the significance of factors. Regression coefficients and 3D contour plots were used to quantify the relationship
between panel properties and the two test factors. The results from this study indicated that the preheating retention time
was a significant factor for both modulus of rupture (MOR) and modulus of elasticity (MOE), the steam pressure was a significant
factor for internal bond strength (IB), MOR and MOE, whereas both factors were insignificant for thickness swelling, water
absorption and linear expansion. The properties of MDF panels were quadratic functions of retention time and steam pressure.
Compared to the ANSI standard for 120-grade MDF, most panels with a nominal density of 950 kg/m3 had very high IB (>1 MPa) and acceptable MOR, MOE and dimension stabilities. These results suggest that black spruce bark
residues can be considered as a potentially suitable raw material for manufacturing MDF products. 相似文献
13.
Cheng Xing S. Y. Zhang James Deng Bernard Riedl Alain Cloutier 《Wood Science and Technology》2006,40(8):637-646
The properties of medium-density fiberboard (MDF) panels as affected by wood fiber characteristics were investigated. Wood chips from three softwood and one hardwood species were refined under the same refining conditions to make four different types of fibers. The resulting fibers were characterized by fiber size distribution, bulk density, pH value, and buffering capacity. Using the same resin system and hot-pressing parameters, MDF panels were produced and evaluated for internal bonding (IB), modulus of rupture (MOR), modulus of elasticity (MOE), thickness swelling, and linear expansion. The pH values and alkaline buffering capacities of raw materials were reduced considerably after refining. IB was strongly related to the pH value of fibers. The mechanical properties increased with alkaline buffering capacity. IB, MOR, and MOE increased with the bulk density of fibers. Increased proportions of coarse fibers had negative effects on the panel mechanical properties. 相似文献
14.
生物酶预处理对秸秆中密度纤维板性能的影响 总被引：1，自引：0，他引：1
针对稻草和麦秸原料的特点,分别用木聚糖酶、漆酶／碳源系统(LCS)和脂肪酶对原料进行生物酶预处理用机械磨浆方法制备纤维,以木质纤维板用脲醛树脂作胶黏剂,压制秸秆中密度板,并探讨酶处理对秸秆纤维板性能的影响。结果表明:各种生物酶预处理对稻草和麦秸纤维板的性能都有一定的改善,同软化处理相比,经三种生物酶处理后的长纤维的比例明显增加,而细小纤维的含量则明显降低,IB均有不同程度的改进,其中木聚糖酶对此两项指标的改进效果更好。经木聚糖酶预处理后压制的密度达到0．8 g／cm3以上的纤维板的性能如下:麦草纤维板的IB为0．75 MPa,MOE为3 960 MPa,MOR为37．60 MPa,TS为21．29％。除TS外,均优于GB／T11718-1999标准要求。而稻草纤维板的IB为0．73 MPa,MOE为2 618 MPa,MOR为21．35 MPa,TS为21．19％,其中MOR与TS均离标准要求还有一定的差距。 相似文献
15.
This study was carried out to elucidate the effect of defibration temperature in the range 171–202°C on the properties of 12-mm thick MDF boards made without synthetic resins from softwood fibers activated by laccase treatment for the generation of phenoxy radicals on the fiber surfaces. Laccase treatment generated radicals in the fibers. An increase in defibration temperature improved the reactivity of fibers during laccase-catalyzed oxidation. The number of radicals detected in the fibers after laccase treatment in water suspension and the fiber oxygen consumption during the treatments increased with an increase in defibration temperature, while a concurrent improvement was observed in the mechanical strength and thickness swell of dry-process MDF boards made from fibers refined at different temperatures and treated with laccase in the refiner blowline. The different fiber reactivities or board properties were not due to a presence of different amounts of lignin remaining on the fiber surfaces after acetone extraction. The probable reason for them was the fact that the amount of low-molecular weight lignin, a reactive substrate for laccase, increases with increasing defibration temperature. The adhesion occurring during pressing is thus likely to involve coupling or other reactions of radicals located on adjacent fibers, whereby interfiber covalent bonds are formed. 相似文献
16.
Fourier-transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) were used to study ambient-aged wood
fibers and their effects on the mechanical properties of medium-density fiberboard (MDF). It was found that MDF made with
ambient-aged fibers had poorer mechanical properties than MDF made with fresh fibers; this difference resulted from the alterations
of surface characteristics of wood fibers after ambient aging, which led to poor wettability of the urea–formaldehyde (UF)
resin applied to the aged wood fibers. After 6 months of ambient aging, the concentration of carbonyl groups in the fibers
increased by 144%, while the pH value of wood fiber decreased from 5.2 to 4.7. SEM showed that much more UF resin agglomerated
on the surface of ambient-aged fibers and the breakage of MDF made with aged fiber frequently occurred at the resin-fiber
interfaces, indicated the poorer wettability of UF resin to fibers due to the decrease in surface energy after aging. 相似文献
17.
Jianying Xu Ragil Widyorini Hidefumi Yamauchi Shuichi Kawai 《Journal of Wood Science》2006,52(3):236-243
Binderless fiberboards with densities of 0.3 and 0.5 g/cm3 were developed from kenaf core material using the conventional dry-manufacturing process. The effects of steam pressure (0.4–0.8
MPa) and cooking time (10–30 min) in the refining process, fiber moisture content (MC) (10%, 30%), and hot-pressing time (3–10
min) on the board properties were investigated. The results showed that kenaf core binderless fiberboards manufactured with
high steam pressure and long cooking time during the refining process had high internal bond (IB) strength, low thickness
swelling (TS), but low bending strength values. The binderless fiberboards made from 30% MC fibers showed better mechanical
and dimensional properties than those from air-dried fibers. Hot-pressing time was found to have little effect on the IB value
of the binderless board at the refining conditions of 0.8 MPa/20 min, but longer pressing time resulted in lower TS. At a
density of 0.5 g/cm3, binderless fiberboard with the refining conditions of 0.8 MPa/20 min recorded a modulus of rupture (MOR) of 12 MPa, modulus
of elasticity (MOE) of 1.7 GPa, IB of 0.43 MPa, and 12% TS under the optimum board manufacturing conditions.
Part of this article was presented at the 54th Annual Meeting of the Japan Wood Research Society, Hokkaido, August 3–5, 2004 相似文献
18.
The effects of thermomechanical refining pressures, varying from 2 to 18 bars, on the cell-wall properties of refined wood fibers of a 54-year-old loblolly pine (Pinus taeda L.) with reference to both juvenile (JW) and mature wood (MW) were investigated using nanoindentation and atomic force microscopy. The results of this study indicate that refining pressure plays a significant role in the physical damage sustained by refined wood fibers. No obvious damage was observed in the cell walls of MW fibers refined at 2 and 4 bar. Nanocracks (<500 nm in width) were found in fibers refined at pressures in the range of 2–12 bar for JW and 6–12 bar for MW, and micro cracks (>3,000 nm in width) were found in both MW and JW fibers subjected to a refining pressure of 14 and 18 bar. The micro damage to the fibers refined at higher pressures was more severe inside the lumen than on the surface of the fibers, and the lumen or S3 layer was significantly damaged. The elastic modulus, hardness, and creep resistance of MW fibers were higher than those of the JW fibers subjected to the same refining-pressure conditions. The elastic modulus and hardness decreased, whereas nanoindentation creep increased, with increasing refining pressure. This study also suggests that lower refining pressures (<4 bar) and higher pressures (>14 bar for MW and >12 bar for JW) should be avoided in the manufacture of fiberboards and wood fiber–polymer composites, because of the lower aspect ratio of the fiber bundles, shorter length of the fibers and fines, and severe damages to the fiber cell walls. 相似文献
19.
稻草原料酸碱性及稻草中密度纤维板的性能 总被引：8，自引：2，他引：8
测试分析了稻草原料的ｐＨ值和缓冲容量，分别使用脲醛树脂胶和异氰酸酯胶在特定工艺条件下压制了稻草中密度纤维板，并测试了板材性能。结果表明：１）稻草秸秆原料呈弱碱性，缓冲容量远高于普通木材；经热磨处理获得的稻草纤维呈弱酸性，其缓冲容量虽较稻草秸秆有一定幅度的下降，但仍高于普通木材；２）脲醛树脂或异氰酸酯稻草中密度纤维板的性能都明显优于相应的碎料板；在密度０．８０ｇ／ｃｍ３和施胶量１７％的条件下，脲醛树脂稻草中密度纤维板性能达到国标ＧＢ／Ｔ１７６５７－１９９９一等品的要求，在密度０．８０ｇ／ｃｍ３和施胶量６％的条件下，异氰酸酯稻草中密度纤维板性能达到国标ＧＭ／Ｔ１７６５７－１９９９优等品要求。 相似文献