共查询到20条相似文献,搜索用时 15 毫秒
1.
In order to improve the properties by chemical modification and to optimize the alkali concentration,we treated Borassus fruit fine fibers with aqueous sodium hydroxide solutions of different concentrations.In each case,the tensile properties of the fibers were determined.The morphology of the untreated and alkali treated fibers was observed using scanning electron microscope.The surface of the fibers became rough on alkali treatment.The tensile properties of the fibers improved on alkali treatment.The fibers attained maximum tensile properties when treated with 15% aqueous sodium hydroxide solution and decreased thereafter.The crystallinity index of the fibers showed a similar trend.The thermal stability of the alkali treated fibers was found to be higher than that of untreated fibers.Further,the char content was maximum for fibers treated with alkali having concentration of 15% and above.The chemical composition indicated that the percentageof α-cellulose was maximum when the fibers were treated with 15% aqueous sodium hydroxide solution and then decreased thereafter thus indicating the beginning of degradation of the fibers at higher concentrations.Thus,the optimum concentration of NaOH was established as 15% for alkali treatment of the Borassus fibers. 相似文献
2.
Ankita Hazarika 《Wood material science & engineering》2017,12(1):24-39
Wood polymer nanocomposites (WPNCs) based on nano-ZnO and nanoclay were prepared by impregnation of melamine formaldehyde–furfuryl alcohol copolymer, 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU), a cross-linking agent and a renewable polymer obtained as a gum from the plant Moringa oleifera under vacuum condition. Fourier transform infrared spectroscopy (FTIR) and X-ray diffractometry (XRD) studies were employed for the characterization of modified ZnO and WPNCs. The change in crystallinity index (CrI) value of the cellulose in wood and the distribution of ZnO nanoparticles in composites were determined using FTIR and XRD. Scanning electron microscopy and Transmission electron microscopy showed the presence of nanoparticles and nanoclay in the cell lumen or cell wall of wood. An enhanced UV resistance property was shown by the treated wood samples as judged by lower weight loss, carbonyl index, lignin index, cellulose CrI values, and mechanical property loss compared to the untreated wood samples. Wood polymer composites treated with 3 phr each of nanoclay, ZnO, and the plant gum showed an improvement in mechanical properties, flame-retarding properties, thermal stability, and lower water uptake capacity. 相似文献
3.
探讨了低温等离子体预处理对玻璃纤维增强木塑复合材料力学性能的影响。结果表明:1)低温等离子体处理可有效改善玻璃纤维和木塑复合材料之间的界面相容性。较优预处理参数为:氧气氛围,处理功率100W,处理时间90s。2)玻璃纤维经等离子预处理可有效提高木塑复合材料的力学性能,但处理功率为200W,处理时间180s时,可能对纤维结构造成破坏,导致复合材料的力学性能降低。3)微观形貌特征显示,处理组复合材料中的应力得到有效传递,纤维破坏形式以断裂为主;纤维及聚合物基体表面存在不同程度的刻蚀,从而增加了比表面积,有利于两者之间的界面相互作用。4)等离子体处理主要通过改变基材表面化学组成及刻蚀作用,两者协同可提高聚合物基体与玻璃纤维之间的界面结合能力。 相似文献
4.
The morphological, physical, and mechanical properties of the nonwood plant fiber bundles of ramie, pineapple, sansevieria,
kenaf, abaca, sisal, and coconut fiber bundles were investigated. All fibers except those of coconut fiber had noncircular
cross-sectional shapes. The crosssectional area of the fiber bundles was evaluated by an improved method using scanning electron
microscope images. The coefficient factor defined as the ratio of the cross-sectional area determined by diameter measurement,
to the cross-sectional area determined by image analysis was between 0.92 and 0.96 for all fibers. This indicated that the
area determined by diameter measurement was available. The densities of the fiber bundles decreased with increasing diameters.
The diameters of each fiber species had small variation of around 3.4%-9.8% within a specimen. The tensile strength and Young’s
modulus of ramie, pineapple, and sansevieria fiber bundles showed excellent values in comparison with the other fibers. The
tensile strength and Young’s modulus showed a decreasing trend with increasing diameter of fiber bundles. 相似文献
5.
The modulus of elasticity and the modulus of rupture during static bending in the radial direction, and the viscoelastic properties in the radial direction in the temperature range 20°–100°C of hinoki (Chamaecyparis obtusa) swollen in organic liquids with two or more functional groups in a molecule were compared with those of wood swollen by moisture. The wood swollen in organic liquids in or near the swelling equilibrium, but not that swollen in organic liquids distant from the swelling equilibrium, showed higher moduli of elasticity and rupture than the wood swollen to a similar degree by moisture. This suggests that wood exists in an unstable state as it approaches the swelling equilibrium, rendering it highly flexible and weak. During the first viscoelastic measurements for wood swollen in various organic liquids, thermal softening was observed in 40°–60°C range and above 80°C, though this softening disappeared during the second measurement. The softening observed in the 40°–60°C range and above 80°C was thought to have been caused by the redistribution of liquid toward the equilibrium state at a higher temperature and the swelling accompanying an elevated temperature, respectively.Part of this report was presented at the 49th Annual Meeting of the Japan Wood Research Society, Tokyo, April 1999 相似文献
6.
This study reports the effects of shifting cultivation at slashing stage on soil physicochemical properties at Bandarban Sadar Upazila in Chittagong Hill Tracts of Bangladesh. At this initial stage of ... 相似文献
7.
8.
9.
10.
Acetylation of wood was carried out in acetic anhydride only, acetic anhydride/xylene 1:1 (v/v), and acetic anhydride/pyridine 4:1 (v/v) solutions. The antishrink efficiency (ASE), hygroscopic properties, vibrational properties, and bending strength were compared among the three reaction solutions. The ASE was a simple function of weight gain (WG); the equilibrium moisture content at a given WG differed among the reaction solutions. Based on this fact and the results of repeated water soaking and oven-drying tests, it was found that the bulking effect was a major factor, and that decreased hygroscopicity contributes only slightly to the dimensional stabilization by acetylation. The difference in equilibrium moisture content among reaction solutions appears more significant in block samples than wood meal, probably due to the fiber-to-fiber bonds in the former. The tendencies for change in the specific Youngs modulus and the loss tangent differed among reaction solutions, whereas in the static bending test the difference was not marked.Part of this report was represented at the 52nd Annual Meeting of the Japan Wood Research Society, Gifu, April 2002 相似文献
11.
12.
通过工艺实验,对重组木和单板条平行胶合材(PSL)的主要力学性能进行了研究。采用杨木、落叶松和桦木小径材作为重组木原料;以胶合板厂的杨木及桦木旋切后的废单板条作为PSL的原料。在实验室条件下,利用低质小径木和木材加工剩余物,制造出具有高强度的结构用重组木和PSL;对两种人造木材的工艺条件进行了比较与分析,分别提出了影响重组木和PSL力学强度的主要工艺因子。结果表明热压压力是影响重组木力学强度的一个重要工艺因子,而单板条长厚比对PSL也是一个重要工艺因子。 相似文献
13.
根据中外木材物理力学性质试验方法标准的差异,提出了中外木材密度、干缩性和力学强度等试验数据的换算方法,以解决两类木材试验数据的对比问题。 相似文献
14.
15.
Rosewood(Pterocarpus erinaceus Poir.)is valued for flooring,ornaments,musical instruments and furniture-making due to its durability,strength,beauty and acoustic properties.It coppices easily which could boost its continual supply.Compression parallel to grain,Modulus of Elasticity(MOE)and Modulus of Rupture(MOR)within coppiced and non-coppiced boles were determined.These properties decreased along both types of boles.Strength values for the heartwood were also greater than those for the sapwood of each type of bole.MOE,MOR and compression for non-coppiced stems were greater than those from the coppiced stems.The differences were significant(p<0.05).Mechanical properties from the coppiced and non-coppiced boles are comparable.Both have strength properties comparable with those of species widely used for railway sleepers,structural supports,flooring,veneer,furniture,cabinetry,truss and mine props.Therefore,coppiced wood could supplement non-coppiced wood for industrial applications which require strength. 相似文献
16.
从四川乐山和广元两地4处各采集3株6 a生的台湾桤木作为试验样木,采用典型相关分析方法对木材力学性质与立地条件进行了分析。结果表明:降低土壤的氮和pH值,有利于提高木材的抗弯弹性模量、抗弯强度和冲击韧性;木材的抗弯强度、冲击韧性和抗劈力随着土壤的钾和磷含量、年降雨量和日照时数的增大而降低。 相似文献
17.
不同栽培林龄和轮次的杨树人工林土壤理化性质 总被引:1,自引:0,他引:1
采用空间代替时间的方法,构建了不同栽培林龄和轮次的杨树人工林试验样地,测定了土壤主要物理化学性质.结果表明,不同栽培轮次土壤密度值表现为1轮11年生>2轮9年生,随着林龄增加,土壤密度呈逐渐下降趋势,表现为2轮3年生>2轮6年生>2轮9年生,且各样地之间呈显著差异;土壤饱和持水量、毛管持水量、毛管孔隙度和总孔隙度在各样地之间的变化无明显差异,而土壤非毛管孔隙度的变化则呈显著差异,在不同林龄样地上呈极显著差异.试验结果还显示,表层0~10 cm土壤中各养分元素的含量都对应地高于10~ 30 cm土层的含量,而pH值则呈相反的变化趋势;在不同栽培轮次和林龄的杨树人工林样地上对应土层土壤养分元素无明显的变化规律. 相似文献
18.
19.
不同林型下土壤理化性质的差异研究 总被引:5,自引:0,他引:5
为了探讨杨树林、刺槐林的增产机理,本文从土壤理化性质、土壤养分含量等方面,对杨树林、刺槐林与林外进行调查分析。结果表明:杨树林和刺槐林较大幅度地改善了土壤孔隙度、含水量、养分含量等等;杨树林和刺槐林在提高土壤肥力方面有着重要意义。 相似文献
20.
杨村新无性系木材物理力学性质的研究 总被引:4,自引:0,他引:4
研究了7个杨树新无性系和I-69杨的木材物理力学性质。结果表明,杨木新无性系的物理力学性质等主要指标均属于小至甚小级,无性系间物理力学性质差异显著,据此可用木材物理力学性质因子选育优良无性系。尽管新无性系的生长速度超过I-69杨,但由于其某些强度指标低于I-69杨,8年生的速生材尚不能完全替代11年生的I-69杨使用,因此不能作为建筑结构材使用。 相似文献