Weak Expansive Soil Physical Properties Modification by Means of a Cement-Jute Fiber

Sixteen groups of comprehensive tests have been conducted to investigate the modifications in the physical properties of a weak expansive soil due to the addition of a cement jute fiber.The tests have been conducted to analyze the liquid plastic limit,the particle distribution and the free expansion rate.The results show that:(1)With an increase in the cement-jute fiber content,the free expansion rate of the modified expansive soil gradually decreases,however,such a rate rebounds when the fiber content exceeds 0.5%and the cement content exceeds 6%.(2)With an increase in the cement percentage,the particle unevenness coefficient(Cu)and curvature coefficient(Cc)of the modified expansive soil tend to grow gradually.The Cc coefficient reaches 1.0 when the cement content is 6%.The unevenness coefficient of 16 soil samples is greater than 5.0,however,the Cu coefficient decreases when the cement content reaches 6%.(3)The plastic limit of soil increases as the cement content is made higher,while the liquid limit and plastic index decrease gradually.When the content of the modified material is 2%+0.1%~2%+0.7%(Cement content+jute fiber content),the change of particle size distribution is most obvious.(4)When the contents of cement and jute fiber are is 6%and 0.5%,respectively,the modification induced in the physical properties of soil samples corresponds to the best case.

Enhancing mechanical behavior of micaceous soil with jute fibers and lime additives

Micaceous soils are common in many tropical countries and regions,and in some locations with moderate climate.The soils are spongy and unstable when loaded and are not considered suitable as construction material in earth structures.To resolve the issue,this work examined performance of micaceous soil reinforced with a combination of jute fibers,hydrated lime or slag-lime.A total of 28 sample sets were prepared at various dosages.Unconfined compression tests were conducted on the samples cured for 7 d and 28 d,respectively.The test results suggested that the unconfined compressive strength(UCS)and material stiffness were increased with the inclusion of up to 1%fiber and decreased if additional fibers were used.The ductility was improved consistently with up to 1.5%fiber content.The inclusions of fibers combined with hydrated lime or slag-lime further enhanced strength and stiffness of micaceous soil,and the improvement depended on the dosages used.For the dosages examined,jute fibers outweighed lime and slag in gaining ductility,and the optimal fiber content was 1%where strength and ductility were considered.

A Novel Approach of Dyeing Jute Fiber with Reactive Dye after Treating with Chitosan

Jute is generally not dyed with reactive dye though it is a cellulosic fiber. Reactive dye is extensively used to dye cotton, viscose and other cellulosic fibers whereas jute is dyed with basic dye. This paper presents a novel approach to dye the jute fiber with reactive dye after treating with chitosan. Jute fabric was treated with chitosan solution at different con- centrations (0.5%, 1%, 2%, 3% and 4%) and then dyed with reactive dye. The depth and fastness of shade of dyed fabric were analyzed by comparing the chitosan treated samples with untreated dyed fabric samples. It has been found that, the dyebath exhaustion is increased with the increment of chitosan concentrations. The exhaustion percentages have found 36.79%, 41.59%, 48.33%, 54.46% and 58.75% for the fabric treated with 0.5%, 1%, 2%, 3% and 4% chitosan solution respectively, while the exhaustion of dyebath is only 23.15% for untreated fabric. The K/S values (at λmax = 540 nm) of dyed samples have found 4.93, 6.77, 10.5, 14.07, 15.57 and 2.37 for 0.5%, 1%, 2%, 3%, 4% and untreated fabric respectively. The color fastness to washing and rubbing of the dyed fabrics was also evaluated. In case of dry rubbing, both types of fabric have shown almost similar fastness ratings. However, chitosan treated fabrics have shown inferior fastness rating in case of wet rubbing and washing, particularly for the fabrics at higher chitosan concentrations.

Effect of Fiber Loading on the Dynamic Mechanical Properties of Jute Fiber Reinforced Polypropylene Composites

Jute fiber (woven fabric, 1 × 1 plain weave) reinforced polypropylene matrix composites were prepared by compression molding with various fiber loading such as 30%, 40%, 46%, 50%, 55% by weight. The mechanical properties such as tensile strength (TS), bending strength (BS), tensile modulus (TM), bending modulus (BM) and impact strength (IS) of the composite were assessed and analyzed. The highest value of TS, BS, TM, BM and IS were 68.1 MPa, 94.1 MPa, 2936 MPa, 4831 MPa and 14.5 kJ/m2 respectively with 50% fiber loading by weight. It was found that the mechanical properties of the composites were increased with the increase in jute fiber content up to 50% by weight;however, further increase in fiber loading the value decreased. On the basis of fiber content, 50% fiber reinforced composites had the optimum set of mechanical properties. Initially the water absorption rate was higher and then it became slower and static with time. Chemical ageing test with various chemical media such as H2O2, NaOH, HCl and NaCl were performed up to 168 hours. After first 24 hours the composite samples showed gradual weight gain (%) and then the weight gain was become slow and steady in the chemical solution.

Preparation and Reinforcement Adaptability of Jute Fiber Reinforced Magnesium Phosphate Cement Based Composite Materials

To improve the brittleness characteristics of magnesium phosphate cement-based materials(MPC)and to promote its promotion and application in the field of structural reinforcement and repair,this study aimed to increase the toughness of MPC by adding jute fiber,explore the effects of different amounts of jute fiber on the working and mechanical properties of MPC,and prepare jute fiber reinforced magnesium phosphate cement-based materials(JFRMPC)to reinforce damaged beams.The improvement effect of beam performance before and after reinforcement was compared,and the strengthening and toughening mechanisms of jute fiber on MPC were explored through microscopic analysis.The experimental results show that,as the content of jute fiber(JF)increases,the fluidity and setting time of MPC decrease continuously;When the content of jute fiber is 0.8%,the compressive strength,flexural strength,and bonding strength of MPC at 28 days reach their maximum values,which are increased by 18.0%,20.5%,and 22.6%compared to those of M0,respectively.The beam strengthened with JFRMPC can withstand greater deformation,with a deflection of 2.3 times that of the unreinforced beam at failure.The strain of the steel bar is greatly reduced,and the initial crack and failure loads of the reinforced beam are increased by 192.1%and 16.1%,respectively,compared to those of the unreinforced beam.The JF added to the MPC matrix dissipates energy through tensile fracture and debonding pull-out,slowing down stress concentration and inhibiting the free development of cracks in the matrix,enabling JFRMPC to exhibit higher strength and better toughness.The JF does not cause the hydration of MPC to generate new compounds but reduces the amount of hydration products generated.

Impregnation of thermoplastic resin in jute fiber mat

Impregnation rate of thermoplastic resin(polypropylene)in jute fiber mat and influence of relative factors on impregnation were studied,aiming to develop the continuous melt impregnation technique and to investigate the effect of impregnation rate and temperature on processing conditions and mechanical properties of natural fiber mat-reinforced thermoplastics.Influence of pressure on porosity of fiber mat and effect of melt viscosity on impregnation rate were also investigated.The modified capillary rheometer was used as apparatus and experimental data were analyzed based on the one-dimension Darcy’s law.Results showed that at a given pressure,the impregnation rate is inversely proportional to melt viscosity and jute fiber mat has higher porosity than glass fiber mat.The architecture,compressibility,permeability and fiber diameter of jute fiber mat were compared with those of glass fiber mat and their effects on impregnation were discussed further.It could be seen that the average diameter of jute fiber is much bigger;the porosity of jute fiber mat is significantly higher and inner bundle impregnation does not exist in jute fiber mat.Therefore,it is not difficult to understand why the impregnation rate in jute fiber mat is 3.5 times higher and permeability is 14 times greater.Kozeny constants of jute and glass fiber mats calculated based on the capillary model are 2950 and 442,respectively.

Studies on Mechanical Properties of Jute/E-Glass Fiber Reinforced Epoxy Hybrid Composites

Hybrid materials of any class are essential for current demands. This paper deals with the hybrid effect of composites made of jute/E-Glass fibers which are fabricated by hand layup method using LY556 Epoxy resin and HY951 hardener. The properties of this hybrid composite are determined by testing like tensile, flexural, impact, and inter laminar shear strength which are evaluated experimentally according to ASTM standards. The result of the test shows that hybrid composite of jute/ E-glass fiber has far better properties than that of jute fiber composite. However, it is found that the hybrid composite has better strength as compared to jute fiber composite fabricated separately with glass fiber.

Mechanical properties of dredged soil reinforced by xanthan gum and fibers

Biopolymers have become popular in geotechnical engineering as they provide a carbon-neutral alternative for soil solidification.Xanthan gum(XG)and jute fiber(JF)were selected to solidify the Yellow River dredged soil.The mechanical behavior of solidified dredged soil(SDS)was investigated using a series of uniaxial compression and splitting tension tests at different XG and JF contents and fiber lengths.The results indicate that on the 28th day,the unconfined compressive strength(UCS)values of SDS samples reached 2.83 MPa and splitting tensile strength(STS)of 0.763 MPa at an XG content of 1.5%.When the JF content was greater than 0.9%,the STS of the SDS samples decreased.This is because that the large fiber content weakened the cementation ability of XG.The addition of JF can significantly increase the strain at peak strength of SDS samples.There is a linear relationship between the UCS and STS of the dredged soils solidified by XG and JF.Microanalysis shows that the strength of SDS samples was improved mainly via the cementation of XG itself and the network structure formed by JF with soil particles.The dredged soil reinforced by XG and JF shows better mechanical performance and has great potential for application.

Extraction and structural investigation of jute cellulose nanofibers

Cellulose nanofibrils(CNFs) are a type of natural nanomaterials extracted from plants and animals that have expanding applications in numerous areas benefiting from their inherent properties of renewability,biodegradability,and sustainability.For energy consumption reduction,CNFs were extracted from raw jute fibers,which were not pretreated in a hot alkali or acid solution,by TEMPOmediated oxidation.Synchrotron radiation wide-angle scattering was performed to realize the crystallization of the CNF crystallites;Fourier transform infrared spectroscopy,transmission electron microscopy,and fieldemission scanning electron microscopy were used to characterize the changes in chemical groups and visualized morphology of CNFs.The simplified preparation and shortened cycle should further help the study of the structure–function relationship of jute CNFs subjected to chemical modification.

Production and Properties of Short Jute and Short E-Glass Fiber Reinforced Polypropylene-Based Composites

Short jute fiber (2 - 3 mm) reinforced polypropylene PP-based composites (20% fiber by weight) were fabricated using compression molding and the mechanical properties were evaluated. Tensile strength (TS), tensile modulus (TM), elongation at break (Eb%), flexural strength (FS), flexural modulus (FM), impact strength (IS), and hardness of the composites were found to be 32 MPa, 850 MPa, 12%, 38 MPa, 1685 MPa, 18 kJ/m2 and 96 shore-A, respectively. Then short E-glass fiber (2 - 3 mm) reinforced PP-based composites (20% fiber by weight) were fabricated and mechanical properties were compared with short jute-based composites. Short jute-based composites showed excellent mechanical properties and comparable to short E-glass-based composites. Soil degradation test of both types of composites indi-cated that jute/PP composites significantly lost much of its mechanical properties but E-glass/PP composites retained major portion of its original integrity. Interfaces of the degraded composites were investigated by scanning electron microscopy and supported the biodegradation properties of jute/PP composites.

黄麻韧皮纤维活性物质鉴定及抑菌效果分析

采用溶剂法从黄麻韧皮纤维中提取黄酮、多糖、生物碱3种成分,并对提取物的化学组分及抑菌效果进行测定分析。结果表明,3种提取物中总黄酮、总多糖、总生物碱含量分别为17.36 mg/g、3.57 mg/g、61.01μg/g。高效液相色谱法(HPLC)检测出黄酮类提取物主要包括异槲皮素(167.47μg/g)、槲皮素(12.35μg/g)、木犀草素(6.41μg/g)、山奈酚(6.26μg/g)等;多糖类提取物中的单糖组分有半乳糖(0.41 mg/g)、半乳糖醛酸(0.43 mg/g)、阿拉伯糖(1.03 mg/g)等;生物碱类提取物主要组分为盐酸小檗碱(9.97μg/g)。纸片扩散法、二倍稀释观察法、扫描电镜分析显示,3种提取物对金黄色葡萄球菌、大肠杆菌、痢疾杆菌均能产生不同程度的抑制效果。综上,黄麻韧皮纤维中的活性物质较为丰富,且具有良好的抑菌性能。

麻纤维/聚乳酸包装盒模压成型工艺与性能研究

采用模压成型工艺制备了麻纤维/聚乳酸复合材料包装盒,研究了模压压力、加压速度、模具温度对包装盒的拉伸强度与翘曲变形的影响,分析了产生相应变化的微观机理。实验结果表明,在一定范围内,适当增加模压压力,有利于提高复合材料包装盒的力学强度,降低翘曲变形;增加加压速度,对复合材料包装盒力的学性能的影响不大,但会增加翘曲变形;模具温度为50℃时,包装盒的翘曲变形最小。

Influence of Polyester Resin Treatment on Jute Fabrics for Geotextile Applications

In this study, jute woven fabrics (1 × 1 plain, twill, zigzag and diamond weave) were manufactured from 100% raw jute yarn. The fabric specimens were treated by 5%, 10%, 15%, 20% and 25% unsaturated polyester resin where styrene monomer used as a solvent and 1% methyl ethyl ketone peroxide (MEKP) was used as initiator. Two bar pressure was applied for complete wetting of the fabric by a Padder and curing was done at 130?C for 10 minutes. The physico-mechanical characteristics of untreated and treated samples were examined and evaluated. It was revealed that moisture content (MC) and water absorbency of the treated specimens were decreased with the increase of resin percentage (%) in the fabrics. MC and water absorbency were maximum decreased up to 50.23% and 60.14% respectively by 25% resin treatment. On the other hand, bending length (BL), flexural rigidity (FR), flexural modulus (FM) and tensile strength (TS) were enhanced with the increase of resin percentage in the fabrics which resulted higher fabric stiffness. The maximum improvement of BL, FR, FM and TS were found to be 6.67%, 56.04%, 10.57% and 18.75% respectively in comparison to untreated sample. Soil degradation tests exhibited that 33.59% TS loss occurred for untreated specimens where only 8.04% loss of TS found for 25% resin treated one. Furthermore, jute based twill, zigzag and diamond fabrics were also treated by 10%, 15%, 20% and 25% resin, then measured their TS and compared with plain fabrics. It was revealed that plain fabrics have superior TS over other fabrics. It was also evident that TS enhanced for all the fabrics after resin treatment and maximum increase found for all the fabrics up to 25% resin treatment.

纤维-建筑石膏基复合材料力学及耐水性能研究

为探究黄麻纤维的掺入对于纤维-建筑石膏基复合材料力学及耐水性能影响,使用NaOH对黄麻纤维进行碱处理,随后制备成纤维-建筑石膏基复合材料以测定其力学及耐水性能变化情况。由试验结果可知,与未经过碱液处理黄麻纤维相比,吸水处理25h后黄麻纤维吸水率降低了115.9%;而将25mm的黄麻纤维掺入石膏复合材料中可使其吸水率降低0.7%;经过5%碱处理后黄麻纤维抗拉强度和拉伸模量分别降低了4.76%和6.42%,且25mm的黄麻纤维的加入使得石膏基复合材料的拉伸性能和弯曲性能分别提高2.1MPa和9.6MPa,试验结果表明纤维的加入有效地增加了纤维-建筑石膏基复合材料的力学性能,但对其耐水性能影响较为不显著。

Humidity Diffusion on Jute/Polyester Laminated Composites and Its Effects on Mechanical Properties

Jute is a natural fiber widely used as reinforcement in composites due to its high tensile strength and stiffness,but they can easily absorb water and have their physical properties compromised.The water absorption properties of jute/polyester composites are evaluated according to ASTM D 570 and the effect of humidity in the composite mechanical behavior is also analyzed.The composite showed a pseudo-Fickian behavior and gained 13.37%in weight after the test.It also lost tensile strength and elasticity modulus,and increased its specific deformation.Scanning electron microscope images showed that wet specimens were more subject to cracks,voids and fiber pullout than dry specimens.Failures produced by water diffusion in composite and polymer plasticization,added to breakdown in the fibers’cellulosic structures,justify the change in mechanical properties due to water absorption.

Evaluation of stiffness in a cellulose fiber reinforced epoxy laminates for structural applications:Experimental and finite element analysis

Natural fiber composites have been proved to have the ability to replace the synthetic fiber composites in many structural applications. Unprecedented growth in the field of computational techniques has opened the doors of analysis and simulation of composite materials under various environment.Modelling and simulation using various available softwares saves a lot of time and resources. In the present work, an attempt has been made to analyze the tensile behavior of jute fiber reinforced epoxy based polymer composite materials using the student version of commercially available finite element code Siemens PLM NX 10.0. In most of the structural applications, materials are required to have enough stiffness to resist the shape deformation under normal loading conditions. Therefore, emphasis is given to the load-deformation behavior of the developed composites. A 3-dimensional model of the test specimen was developed using ply-stacking method and the strain-stress values were verified by the available literature. The model showed a good agreement between the experimental and software results. Effect of ply angle, fiber percentage, fiber type, number of layers and weft fiber angle on the stiffness of laminate have been studied.

黄麻韧皮纤维石油醚提取物的化学成分及抑菌分析

为充分利用黄麻资源,试验以黄麻韧皮纤维为原料,采用石油醚加热回流法提取,对提取物分别采用GC-MS法、纸片扩散法进行化学成分及抑菌分析。通过气相色谱-质谱法(GC-MS)分析鉴定出56种化合物,包括开链烃类22种、闭链烃类4种、卤代烃类5种、醇类7种、醛类1种、酚类2种、醚类2种、酮类1种、酸类3种、杂环类3种、酯类6种,其总相对含量分别为60.98%、2.65%、2.62%、22.33%、0.42%、1.35%、1.17%、0.35%、0.59%、2.70%、4.09%。采用纸片扩散法测定出提取物对金黄色葡萄球菌、大肠杆菌均能产生明显的抑制作用,对白色念珠菌抑制作用不明显。结果表明,石油醚可提取黄麻韧皮纤维中的γ-谷甾醇、白藜芦醇、羽扇豆醇、豆甾醇、25-羟基胆固醇、丙丁酚等多种有效药理活性物质,拓展了功能纤维利用价值。

The Effect of Curative Concentration on Thermal and Mechanical Properties of Flexible Epoxy Coated Jute Fabric Reinforced Polyamide 6 Composites

Many researchers have shown interest in the reinforcement of commodity thermoplastic with natural fibers. However, the drawback of natural fibers is their low thermal processing temperatures, that border around 200℃. In this investigation, we tried to improve the thermal stability of natural fibers with the use of flexible epoxy surface coating that could facilitate processing with engineering thermoplastics. Jute fabric and Polyamide 6 (PA6) composites were prepared by compression molding. The thermal decomposition characteristics of the jute fabric were evaluated by using thermo gravimetric analysis (TGA). Mechanical analysis was conducted to evaluate tensile test and three point bending test of composite. It was found that thermal degradation resistance of jute fabric was improved by coating with flexible epoxy resin. Moreover, the flexural modulus improved with increasing curative concentration. The interfacial interaction between the epoxy and PA6 was clearly indicated by the photo micrographs of the polished cross sections of the coated and uncoated jute fabric/PA6 composites.

漆酶/TEMPO体系催化氧化处理对黄麻纤维木质素的影响

采用漆酶/TEMPO体系对黄麻纤维进行催化氧化处理,通过Klason法测定处理前后黄麻纤维中的木质素含量,分别利用凝胶渗透色谱法、有机元素分析法、核磁共振氢谱法测定以二氧六环法从黄麻纤维中提取木质素的分子量及分布、元素含量与化学结构。结果表明:经漆酶/TEMPO处理后黄麻纤维中木质素含量由10.83%降为8.59%,纤维上存留的木质素亦发生了降解,重均分子量由439938 Da降至238704 Da。黄麻纤维经过漆酶/TEMPO体系处理后,木质素的碳元素含量升高,氧元素和—OCH_(3)含量降低,醇羟基数目减少,酚羟基数目稍有下降,并且结构单元的连接方式有所转变,其中β-β、β-1和β-O-4结构比例有所降低,β-5结构增多,说明漆酶/TEMPO催化黄麻纤维木质素发生氧化反应并伴随有一定脱甲基化作用,木质素降解以β-β、β-O-4和β-1键断裂为主,而后形成β-5连接。

基于正交试验法的黄麻纤维增强聚氨酯复合材料综合性能研究

针对黄麻纤维增强聚氨酯复合材料,选取了主要可控工艺参数纤维质量分数、纤维长度、模压压力和纤维表面处理方法作为试验因素,设计了三水平四因素的正交试验,并依据国标要求进行了拉伸、弯曲和冲击等方面的力学性能试验。通过对试验结果进行极差分析,研究了各种工艺参数对黄麻纤维增强聚氨酯复合材料力学性能的影响情况,并找出了针对不同力学性能指标的最优工艺参数组合方案,为提高制品的力学性能提供了工艺改进依据。