红麻韧皮部束纤维抗拉强度的分布规律研究

为探讨红麻韧皮部束纤维抗拉强度的分布规律,将红麻大小植株不同高度、不同层次的韧皮部束纤维进行分离并测定抗拉强度.结果表明,红麻韧皮部束纤维抗拉强度随着植株大小、植株高度及束纤维不同层次的变化在横向和纵向分布上呈现一定的变化规律,推测与红麻纤维发育期间的外界环境条件有密切关系.     

红麻韧皮部束纤维抗拉强度测定的样品准备方法研究

通过5种处理方法分离红麻韧皮部束纤维层,测定各层束纤维的直径d及其所能承受的最大拉力 Fmax,计算束纤维的极限抗拉强度σ.结果表明,采用亚氯酸钠-冰醋酸和草酸铵方法,不仅能够有效地分离红麻韧皮部束纤维层,而且对束纤维的强度影响较小,可以作为红麻韧皮部束纤维抗拉强度测定的样品准备方法,对准确测定和研究红麻束纤维抗拉强度及其分布具有重要意义.     

红麻韧皮部束纤维抗拉强度测定的样品准备方法研究

通过5种处理方法分离红麻韧皮部束纤维层，测定各层束纤维的直径d及其所能承受的最大拉力Fmax，计算束纤维的极限抗拉强度σ。结果表明，采用亚氯酸钠-冰醋酸和草酸铵方法，不仅能够有效地分离红麻韧皮部束纤维层，而且对束纤维的强度影响较小，可以作为红麻韧皮部束纤维抗拉强度测定的样品准备方法，对准确测定和研究红麻束纤维抗拉强度及其分布具有重要意义。     

红麻韧皮部束纤维层的分离及纤维长度分布

采用亚氯酸钠-冰醋酸和草酸铵处理,将不同部位的红麻韧皮部束纤维进行分层,并测定各束纤维层的纤维细胞长度,探讨红麻韧皮部纤维细胞长度的分布规律.     

红麻韧皮部束纤维层的分离及纤维长度分布

采用亚氯酸钠一冰醋酸和草酸铵处理，将不同部位的红麻韧皮部束纤维进行分层，并测定各束纤维层的纤维细胞长度，探讨红麻韧皮部纤维细胞长度的分布规律。     

红麻茎发育的解剖研究初报

本文是对红麻茎发育进行解剖研究的结果。研究表明:红麻茎韧皮纤维层、木质部的发育均以旺长期最快;束纤维横切面积是后分化大于先分化的纤维束,而单纤维横切面积则是先分化大于后分化的纤维;红麻茎木质部发育的速度往往数倍于韧皮部;不同肥料对麻茎生长的影响,N肥以生长前期影响最大,而K肥对麻茎发育的影响以旺长期效果最为明显,作为选纸原料的红麻更应重施K肥。     

红麻茎发育的解剖研究初报

本文是对红麻茎发育进行解剖研究的结果。研究表明：红麻茎韧皮纤维层，木质部的发育均以旺长期最快；束纤维横切面积是后分化大于先分化的纤维束，而单纤维横切面积则是先分化大于后化分的纤维；红麻茎木质部发育的速度往往数倍于韧皮部；不同肥料对麻茎生长的影响，Ｎ肥以生长前期影响最大，而Ｋ肥对麻茎发育的影响以旺长期效果最为明显，作为造纸原料的红麻更应重施Ｋ肥。     

红麻全杆制浆造纸

红麻又名洋麻、槿麻Hibiscus Cannabinus,属锦葵科木槿属,一年生草本植物。株高3—5米,茎粗1—3厘米,生长期4—6个月。红麻易于种植,适应性强。我国每公顷产量有12—18吨,单位面积产量为松木的3—5倍。以重量计算,红麻全杆韧皮部占35—40％。韧皮部纤维属长纤维范畴,相似于松木纤维,木质部     

苎麻纤维产量和质量指标的解剖估测研究

试验于1982～1986年进行,观察测定茎截面纤维细胞的直径和壁厚、茎截面上纤维细胞敷和韧皮部单宁细胞数以及植株的高度,可以一次性定量估测苎麻品种的纤维产量和纤维细度、强力、纤维大小均匀性、原麻含胶率、原麻锈脚等多项质量指标。估测结果与实际测定结果比较,正确率均在80%以上。     

红麻短日条件下自然群体有效株高与始花节位的相关和回归分析

红麻是锦葵科木槿属一年生韧皮纤维作物,以收获韧皮部纤维为主要目的。本研究以海南三亚种植的红麻自然群体为研究对象,分别选取随机选取红麻早熟、中熟、晚熟品种各6个,每个品种随机选取9株测量有效株高和始花节位并对其进行相关分析和回归分析。研究结果表明红麻的始花节位和有效株高呈显著性线性相关。始花节位可以作为红麻纤维产量育种的一个重要育种标记。     

Relationship between chemical composition,crystallinity, orientation and tensile strength of kenaf fiber

The physical properties of natural growth fibers such as chemical composition content and fiber diameter are highly affected by environmental issues such as environmental changes and fiber extraction methods. These irregularities of the natural fibers seriously affect its utilization in composite as reinforcements. In this study, taking into account the importance of the fiber tensile strength, the correlation degrees between the kenaf fiber tensile strength and the fiber chemical composition, crystallinity, orientation degree were analyzed by the grey relational analysis method. Both the kenaf single fiber and fiber bundle were used as XRD and tensile strength test sample. The chemical composition content and the FTIR were carried out to obtain a correct result of the chemical composition content. It found that for the different XRD and tensile strength test samples, the single fiber showed lower crystallinity, higher orientation degree and tensile strength compared with the fiber bundle. The cellulose content and the orientation degree got the higher correlation degree with single fiber tensile strength, which was 0.674 and 0.640. The highest factor associated with the fiber bundle tensile strength was the orientation degree, the correlation degree was 0.747. The hemicellulose content and the crystallinity also got high correlation degree with the fiber bundle strength, which was 0.687 and 0.640.     

Characterization of kenaf phloem fibers in relation to stem growth

Microscopic study on phloem fibers in kenaf stem was carried out to examine the developmental process of phloem fiber and localization of noncellulosic polysaccharides in the cell walls. Histochemical observation showed that layered phloem fiber bundles developed external to the vascular cambium as stems grew after planting, and the number of layered bundles was higher in the bottom region of the stem regardless of growth stage. Based on immunocytochemical observations, cells making up the phloem fiber bundles had thick secondary cell walls containing mixed-linkage, (1 → 3, 1 → 4)-β-d-glucan as a component of hemicellulose. Other polysaccharides present in cell walls, namely xyloglucan, rhamnogalacturonan, and methyl-esterified homogalacturonan, were localized only, in the primary cell walls and/or in the junction between contiguous cells. In addition, mechanical evaluation on isolated kenaf fibers showed that the fiber strength varied by stem maturity and region: both higher tensile strength and initial Young's modulus were recorded in fibers obtained from the middle region of stems harvested 4-6 months after planting.     

Weibull distribution analysis of the tensile strength of the kenaf bast fiber

This paper presents the influence of the gage length on the kenaf fiber Young’s modulus and the tensile strength characterization. Four different gage lengths of 10 mm, 15 mm, 20 mm and 25.4 mm are selected in this study and the tensile testing is performed at a quasi-static loading rate of 1 mm/min. The cross-sectional area of the fiber after failure is considered for the stress calculations. Weibull probability distribution is used to characterize the tensile strength of the kenaf fiber. The Weibull parameters are obtained for the two parameter, three parameter and Weibull of Weibull models and the average tensile strength of the fibers are evaluated. The predicted average tensile strength from all the three approaches are in good agreement with the experimental results for the obtained parameters.     

Effects of plasticizer on the mechanical properties of kenaf/starch bio-composites

Research and development of biodegradable bio-composite can replacement the synthetic polymer materials, which is used for automobile interior materials, finishing materials of air conditioner and refrigerator. To develop both components as biodegradable bio-composite, this research used natural polymer starch as matrix and kenaf fiber as a filler. Various plasticizer(polyvinyl alcohol, polyethylene glycol, glycerol) were added and examined the mechanical properties of the kenaf/starch bio-composites according to these plasticizer. The kenaf bast which cultivated in Korea was retted with 2 % NaOH solution. The plasticizer weighting 10 % of that of matrix was added. kenaf/starch composites were molded with hot press for 30 minutes at 130 °C and 3,500 PSI molding condition. The mechanical properties such as tensile strength, elongation, and young modulus of the kenaf/starch composites were measured. Also, we measured the SEM cross-section images in order to investigate interfacial adhesion properties of fractured surfaces. The order of strength size of composites were G (12.42 MPa) > PVA (9.72 MPa) > PEG (4.73 MPa) samples respectively. The tensile strength of PEG sample is lower than the control sample (5.40 MPa).     

Effect of kenaf and EFB fiber hybridization on physical and thermo-mechanical properties of PLA biocomposites

Kenaf/empty fruit bunch/polylactic acid (kenaf/EFB/PLA) hybrid biocomposites were prepared using hot press technique. The ratio of fiber to polylactic acid was set at 60:40 with 1:1 ratio between kenaf and empty fruit bunch fibers. Physical, mechanical and thermal properties of hybrid biocomposites were subsequently characterized using Fourier transform infrared spectroscopy, scanning electron microscope, X-ray diffraction, thermogravimetric analysis, differential scanning calorimetry, tensile and water absorption tests. Test results indicated that mechanically stronger fiber was able to support the weaker fiber. Hybrid fiber biocomposite had higher crystallinity as compared to single fiber biocomposite. Water absorption of hybrid composite was higher as compared to single fiber composite. Thermal result revealed that hybridization of fiber was not significantly influence the thermal properties of composites. However, the presence of two different fibers proposed good wettability properties, which could reduce the formation of voids at the fibers-polymer interface and produce composites with high stiffness and strength.     

Improving the use of kenaf for kraft pulping by using mixtures of bast and core fibers

Kenaf (Hibiscus cannabinus L.) is a herbaceous annual plant amenable to use as a papermaking raw material. Kraft and soda pulping of kenaf have so far been done exclusively on the bark fraction (about 34–38% of the stem) or whole stem of the plant. Using kenaf bark exploits the higher quality of its bast fibers but reduces the typically high crop yields of this plant. In any case, core kraft pulp has acceptable properties some of which (e.g. tensile index, burst index) can even surpass those of bark pulp. Pulp made from both fractions has been found to exhibit better bonding properties than bark pulp. However, too high a proportion of core fibers can result in difficult drainage, a low tear strength or poor air permeability. These problems restrict the proportion of core that can be mixed with bast fibers, hinders separation of the two fractions and raises operational costs.The primary purpose of this study was to examine the influence of the core–bark ratio on the properties of mixed kenaf pulp. We used unrefined core pulp and refined bark pulp. Based on the results for kraft sacks, obtaining kenaf paper from both fractions has some advantages. Because Gurley air porosity changed dramatically with the proportion of core pulp used, it was used to determine the maximum amount of core fibers to be added to bast fibers. A proportion of up to 34% was found to have no adverse effect on air permeability. Such a proportion allowed paper strength to be preserved with an acceptable tear index (19.8 mN m²/g) and excellent tensile index (72 N m/g). Also, energy consumption was reduced if only the bark fraction was refined. The proposed strategy thus provides increased fiber yields of kenaf per hectare per year and valorizes the core fraction.     

The effect of gelation and curing temperatures on mechanical properties of pultruded kenaf fibre reinforced vinyl ester composites

Process parameters such as gelation and curing temperatures are parameters that influence the pultruded kenaf reinforced vinyl ester composites profile quality and performance. The effect of gelation and curing temperatures on mechanical (tensile, flexural and compression properties) and morphological properties of pultruded kenaf reinforced vinyl ester composites were analyzed. Obtained results indicated that increase of gelation and curing temperatures during the pultrusion process of kenaf reinforced vinyl ester composites influenced the mechanical properties of the composites. When the gelation and curing temperatures were increased, tensile strength, tensile modulus, flexural strength, flexural modulus and compressive strength were affected and they were either increased or decreased. The factors that influenced these results include improper curing, excessive curing, water diffusion, and the problems associated with interfacial bonding between fibre and matrices. The optimum values of the tensile strength for gelation and curing temperatures of kenaf pultruded composites were at 100 °C and 140 °C, tensile modulus at 80 °C and 180 °C, flexural strength at 100 ° and 140 °, flexural modulus at 120 ° and 180 °, and compressive strength at 120 °C and 180 °C, respectively. The scanning electron micrographs of tensile fractured samples clearly show that with the increase in gelation temperature, it creates the lumens between matrix and kenaf fibre thus reducing tensile properties whereas increasing the curing temperature caused less fibre pull out and enhanced fibre/matrix interfacial bonding.     

红麻刚刺性状遗传及其与产量品质性状的关联性研究

本文研究了22个红麻品种茎基部、中部、梢部及叶柄上的刚刺性状的数量分布及纤维产量与品质性状方面的10个数量性状的遗传变异。根据刚刺性状的数量分布分析，刚刺性状数量分布是叶柄多于茎杆，其中茎杆刚刺以基部分布最密；叶柄刚刺以茎中部分布较多；茎杆刚刺三个不同部位的遗传力在86．1％-92．4％之间，其相对遗传进度较高，并有丰富的遗传变异系数，在育种中可通过与少刺或无刺突变体回交和定向轮回选择，可以选育出少刺或无刺高产优质红麻新品种。本研究对红麻产量与品质性状的相关及通径分析，结果表明：刚刺性状与多个性状呈负相关，单株干皮重与皮厚、茎粗、株高、单株鲜茎重呈显著正相关。