共查询到19条相似文献,搜索用时 234 毫秒
1.
2.
3.
4.
5.
6.
7.
8.
9.
《森林与环境学报》2015,(3)
以水载铜基防腐剂季铵铜(ACQ)和铜唑(Cu Az)处理毛竹竹条,采用蒸馏水、二碘甲烷、甲酰胺3种参照液体,测定其在防腐处理竹材表面的接触角,并利用几何平均法计算处理材的表面自由能,探讨防腐处理对竹材表面润湿性的影响。结果表明,竹黄面的表面自由能略高于竹青面,但二者差异不显著(p0.05);ACQ与Cu Az处理材的表面自由能差异显著,ACQ处理材的表面自由能高于Cu Az处理材;与未处理材相比,经过防腐剂处理的竹材,大多数表面自由能有所增加,但是随着载药量升高呈现先上升后下降的趋势;当ACQ载药量达到5.2 kg·m-3,Cu Az达到2.2 kg·m-3,防腐处理材与对照样的表面自由能差异不显著。 相似文献
10.
11.
Boštjan Lesar Miha Humar Frederick A. Kamke Andreja Kutnar 《Wood Science and Technology》2013,47(5):977-992
Hybrid poplar (Populus deltoides × Populus trichocarpa) and Douglas-fir (Pseudotsuga menziesii) wood specimens were densified with three variations of thermo-hydro-mechanical (THM) treatment. The THM treatments differed in the steam environment, including transient steam (TS), saturated steam (SS), and saturated steam with 1-min post–heat treatment at 200 °C (SS+PHT). The bending properties, FTIR spectra, and colour of the THM wood specimens were studied before and after exposure to two different wood decay fungi, brown rot Gloeophyllum trabeum, and white rot Trametes versicolor. The results showed that the performance of densified hybrid poplar wood was considerably poorer than the performance of Douglas-fir heartwood. The FTIR spectra measurements did not show changes in the densified hybrid poplar wood, while some changes were evident in densified Douglas-fir specimens. After fungal degradation, the most prominent changes were observed on the SS+PHT specimens. Colour is one of the most important parameter predominantly influenced by the wood species and the intensity of the densification process for both wood species, while after fungal exposure, the colour of all densified Douglas-fir specimens obtained more or less the same appearance, and densified hybrid poplar specimens resulted in lighter colour tones, indicating that the pattern of degradation of the densified and non-densified specimens are similar. The 3-point bending test results determined that the THM treatment significantly increased the modulus of rupture (MOR) and modulus of elasticity (MOE) of the densified wood specimens, while fungal exposure decreased the MOE and MOR in hybrid poplar and Douglas-fir specimens. 相似文献
12.
13.
Eylem Dizman Tomak Elif Topaloglu Nurgul Ay Umit C. Yildiz 《Wood Science and Technology》2012,46(5):905-918
The objective of this study was to investigate the effect of accelerated aging on compression strength, modulus of rupture, modulus of elasticity, color change, volumetric swelling, and volumetric shrinkage of bamboo specimens with and without node sections. In the study, these properties were compared with those of Scots pine and beech wood specimens. Depending on bamboo sections, the aging procedure reduced modulus of rupture, modulus of elasticity, and compression strength. Bamboo specimens showed relatively high strength properties compared to wood specimens due to having high density. Strength properties increased from bottom to top of bamboo culms. The presence of nodes in the specimens reduced compression strength and modulus of rupture but affected modulus of elasticity slightly. Remarkable color changes in specimens were observed after aging. Volumetric swelling and shrinkage of bamboo specimens exposed to aging decreased probably due to heat effect of aging procedure. 相似文献
14.
Morteza Nazerian Zahra Beygi Rahim Mohebbi Gargari Farhad Kool 《Wood material science & engineering》2018,13(2):73-80
High-quality wood resource scarcity as well as population growth and demand of wood have encouraged the use of alternative sources of lignocellulosic materials. In this study, the possibility of producing particleboard from waste cotton stalks is evaluated. The effects of the independent variables included weight ratio of melamine-formaldehyde to urea-formaldehyde, shelling ratio and the percentage of cotton stalks to poplar in the core layer were analyzed in the form of response surface methodology based on second-order multiple linear regression model. The results showed that there was perfect agreement between the estimated values and observed data, as with an increase in the ratio of melamine-formaldehyde resin to urea-formaldehyde, shelling ration and amount of poplar in the core layer of panels, modulus of rupture, modulus of elasticity and internal bonding increase. The optimal point of use of investigated variables included 18.30% melamine-formaldehyde, 30.35% thickness of the surface layers and 10.70% of poplar in the core layer. 相似文献
15.
16.
The mechanical properties of 613 small clear specimens of 35 species (11 ring-porous hardwoods, 19 diffuse-porous hardwoods,
and 5 softwoods) were evaluated. The aim of the study was to examine indexes of wood quality that are easy to measure and
that exhibit a high correlation with bending performance and hardness that are essential properties of hardwood products.
The modulus of rigidity, dynamic modulus of elasticity, bending properties (modulus of elasticity, modulus of rupture, stress
at the proportional limit, absorbed energy, Tetmajer’s modulus), dynamic energy absorption by an impact bending test, compressive
strength parallel to the grain, shear strength, partial bearing strength, and Brinell’s hardness were measured. A high correlation
was found between dynamic modulus of elasticity and static modulus of elasticity. Bending stress at the proportional limit
was found to be approximately equivalent to the compressive strength parallel to the grain. Static energy absorption correlated
with dynamic energy absorption. Tetmajer’s modulus was found to be closely related to the ratio of the initial stiffness within
the elastic range to the secant modulus at the maximum load. A high correlation was observed between Brinell’s hardness and
partial bearing strength. The difference in the regression coefficients obtained for these correlations between the species
groups was small.
Part of this study was presented at the All Division 5 Conference of IUFRO, Taipei, October 2007 相似文献
17.
Compression control and its significance in the manufacture and effects on properties of poplar LVL 总被引:1,自引:0,他引:1
Summary In order to control the compression effectively, the main processing parameters for hot-pressing of poplar LVL were investigated in this study. Results from an orthogonal experiment show qualitatively that compression of poplar LVL is influenced by pressing pressure and moisture content of the veneers. High press pressure and veneer moisture content lead to high compression during hot pressing. It is shown that compression has significant effects on modulus of elasticity, modulus of rupture, specific gravity and thickness swelling of poplar LVL. Modulus of elasticity, modulus of rupture and specific gravity appear to be directly proportional to compression within the compression range of 5% to 20%. Horizontal shear strength results indicate that, due to inadequate contact, proper glue bond may not be achieved between veneers of LVL with low compression. Thickness swelling appears not sensitive to compression between the compression range of 4% to 10%.The authors wish to acknowledge the financial support from the Natural Sciences and Engineering Research Council of Canada to this study, which was carried out when the first author was a visiting scientist at Wood Science and Technology Centre, University of New Brunswick, Canada. The veneers and adhesive used in this study were provided by Temlam Inc., Ville-Marie, Quebec. Their contribution is gratefully acknowledged. 相似文献
18.
19.
浸渍塑化杨木单板顺纹弯曲性能研究 总被引:1,自引:0,他引:1
本研究以酚醛树脂为浸渍液,杨木单板为木材试样,对经浸渍塑化处理的杨木单板进行三点弯曲试验,探索了木/竹复合层合板的组分材料--塑化杨木单板受不同压力时的顺纹弯曲弹性性能,并分析了其与塑化压力间的关系.结果表明,塑化杨木单板的静曲模量和静曲强度与塑化压力呈非线性关系.通过对杨木单板试验研究,为木材/竹材复合材料制造过程中的结构设计和生产工艺提供一定的理论依据和基本思路,并对产品的设计、组织现场生产和产品质量评估提供一定的参考. 相似文献